Posts with «arduino» label

Tutorial – Google Docs and the Arduino Yún

Introduction

This is the second in a series of tutorials examining various uses of the Arduino Yún. In this article we’ll examine how your Arduino Yún can send data that it captures from the analogue and digital inputs and a real-time clock IC to an online Google Docs spreadsheet. Doing so gives you a neat and inexpensive method of capturing data in real-time and having the ability to analyse the data from almost anywhere, and export it with very little effort.

Getting Started

If you haven’t already done so, ensure your Arduino Yún can connect to your network via WiFi or cable – and get a Temboo account (we run through this here). And you need (at the time of writing) IDE version 1.5.4 which can be downloaded from the Arduino website. Finally, you will need a Google account, so if you don’t have one – sign up here.

Testing the Arduino Yún-Google Docs connection

In this first example we’ll run through the sketch provided by Temboo so you can confirm everything works as it should. First of all, create a spreadsheet in Google Docs. Call it “ArduinoData” and label the first two columns as “time” and “sensor”, as shown in the screen shot below:

Always label the required columns. You can call them whatever you need. For new Google users, the URL shown in my example will be different to yours. Next, copy the following sketch to the IDE:

/*
  SendDataToGoogleSpreadsheet

  Demonstrates appending a row of data to a Google spreadsheet from the Arduino Yun 
  using the Temboo Arduino Yun SDK.  

  This example code is in the public domain.

*/

#include <Bridge.h>
#include <Temboo.h>
#include "TembooAccount.h" // contains Temboo account information

/*** SUBSTITUTE YOUR VALUES BELOW: ***/

// Note that for additional security and reusability, you could
// use #define statements to specify these values in a .h file.

const String GOOGLE_USERNAME = "your-google-username";
const String GOOGLE_PASSWORD = "your-google-password";

// the title of the spreadsheet you want to send data to
// (Note that this must actually be the title of a Google spreadsheet
// that exists in your Google Drive/Docs account, and is configured
// as described above.)
const String SPREADSHEET_TITLE = "your-spreadsheet-title";

const unsigned long RUN_INTERVAL_MILLIS = 60000; // how often to run the Choreo (in milliseconds)

// the last time we ran the Choreo 
// (initialized to 60 seconds ago so the
// Choreo is run immediately when we start up)
unsigned long lastRun = (unsigned long)-60000;

void setup() {

  // for debugging, wait until a serial console is connected
  Serial.begin(9600);
  delay(4000);
  while(!Serial);

  Serial.print("Initializing the bridge...");
  Bridge.begin();
  Serial.println("Done");
}

void loop()
{
  // get the number of milliseconds this sketch has been running
  unsigned long now = millis();

  // run again if it's been 60 seconds since we last ran
  if (now - lastRun >= RUN_INTERVAL_MILLIS) {

    // remember 'now' as the last time we ran the choreo
    lastRun = now;

    Serial.println("Getting sensor value...");

    // get the value we want to append to our spreadsheet
    unsigned long sensorValue = getSensorValue();

    Serial.println("Appending value to spreadsheet...");

    // we need a Process object to send a Choreo request to Temboo
    TembooChoreo AppendRowChoreo;

    // invoke the Temboo client
    // NOTE that the client must be reinvoked and repopulated with
    // appropriate arguments each time its run() method is called.
    AppendRowChoreo.begin();

    // set Temboo account credentials
    AppendRowChoreo.setAccountName(TEMBOO_ACCOUNT);
    AppendRowChoreo.setAppKeyName(TEMBOO_APP_KEY_NAME);
    AppendRowChoreo.setAppKey(TEMBOO_APP_KEY);

    // identify the Temboo Library choreo to run (Google > Spreadsheets > AppendRow)
    AppendRowChoreo.setChoreo("/Library/Google/Spreadsheets/AppendRow");

    // set the required Choreo inputs
    // see https://www.temboo.com/library/Library/Google/Spreadsheets/AppendRow/ 
    // for complete details about the inputs for this Choreo

    // your Google username (usually your email address)
    AppendRowChoreo.addInput("Username", GOOGLE_USERNAME);

    // your Google account password
    AppendRowChoreo.addInput("Password", GOOGLE_PASSWORD);

    // the title of the spreadsheet you want to append to
    AppendRowChoreo.addInput("SpreadsheetTitle", SPREADSHEET_TITLE);

    // convert the time and sensor values to a comma separated string
    String rowData(now);
    rowData += ",";
    rowData += sensorValue;

    // add the RowData input item
    AppendRowChoreo.addInput("RowData", rowData);

    // run the Choreo and wait for the results
    // The return code (returnCode) will indicate success or failure 
    unsigned int returnCode = AppendRowChoreo.run();

    // return code of zero (0) means success
    if (returnCode == 0) {
      Serial.println("Success! Appended " + rowData);
      Serial.println("");
    } else {
      // return code of anything other than zero means failure  
      // read and display any error messages
      while (AppendRowChoreo.available()) {
        char c = AppendRowChoreo.read();
        Serial.print(c);
      }
    }

    AppendRowChoreo.close();
  }
}

// this function simulates reading the value of a sensor 
unsigned long getSensorValue() {
  return analogRead(A0);
}

Now look for the following two lines in the sketch:

const String GOOGLE_USERNAME = "your-google-username";
const String GOOGLE_PASSWORD = "your-google-password";

This is where you put your Google account username and password. For example, if your Google account is “CI5@gmail.com” and password “RS2000Escort” the two lines will be:

const String GOOGLE_USERNAME = "CI5@gmail.com";
const String GOOGLE_PASSWORD = "RS2000Escort";

Next, you need to insert the spreadsheet name in the sketch. Look for the following line:

const String SPREADSHEET_TITLE = "your-spreadsheet-title";

and change your-spreadsheet-title to ArduinoData. 

Finally, create your header file by copying the the header file data from here (after logging to Temboo) into a text file and saving it with the name TembooAccount.h in the same folder as your sketch from above. You know this has been successful when opening the sketch, as you will see the header file in a second tab, for example:

Finally, save and upload your sketch to the Arduino Yún. After a moment or two it will send values to the spreadsheet, and repeat this every sixty seconds – for example:

If your Yún is connected via USB you can also watch the status via the serial monitor.

 One really super-cool and convenient feature of using Google Docs is that you can access it from almost anywhere. Desktop, tablet, mobile… and it updates in real-time:

So with your Yún you can capture data and view it from anywhere you can access the Internet. Now let’s do just that.

Sending your own data from the Arduino Yún to a Google Docs Spreadsheet

In this example we’ll demonstrate sending three types of data:

With these types of data you should be able to represent all manner of things. We use the RTC as the time and date from it will match when the data was captured, not when the data was written to the spreadsheet. If you don’t have a DS3232 you can also use a DS1307.

If you’re not familiar with these parts and the required code please review this tutorial. When connecting your RTC – please note that SDA (data) is D2 and SCL (clock) is D3 on the Yún.

The sketch for this example is a modified version of the previous sketch, except we have more data to send. The data is captured into variables from the line:

// get the values from A0 to A3 and D7, D8

You can send whatever data you like, as long as it is all appended to a String by the name of rowdata. When you want to use a new column in the spreadsheet, simply append a comma “,” between the data in the string. In other words, you’re creating a string of CSV (comma-separated values) data. You can see this process happen from the line that has the comment:

// CSV creation starts here!

in the example sketch that follows shortly. Finally, you can alter the update rate of the sketch – it’s set to every 60 seconds, however you can change this by altering the 60000 (milliseconds) in the following line:

const unsigned long RUN_INTERVAL_MILLIS = 60000;

Don’t forget that each update costs you a call and some data from your Temboo account – you only get so many for free then you have to pay for more. Check your Temboo account for more details.

So without further ado, the following sketch will write the values read from A0~A3, the status of D7 and D8 (1 for HIGH, 0 for LOW) along with the current date and time to the spreadsheet. Don’t forget to update the password, username and so on as you did for the first example sketch:

#include <Bridge.h>
#include <Temboo.h>
#include "TembooAccount.h" // contains Temboo account information
#include "Wire.h"
#define DS3232_I2C_ADDRESS 0x68

unsigned long analog0, analog1, analog2, analog3;
int digital7 = 7;
int digital8 = 8;
boolean d7, d8;
byte second, minute, hour, dayOfWeek, dayOfMonth, month, year; // for RTC

const String GOOGLE_USERNAME = "your-google-username";
const String GOOGLE_PASSWORD = "your-google-password";
const String SPREADSHEET_TITLE = "your-spreadsheet-title";

// update interval in milliseconds (every minute would be 60000)
const unsigned long RUN_INTERVAL_MILLIS = 60000; 
unsigned long lastRun = (unsigned long)-60000;

void setup() 
{
  // activate I2C bus
  Wire.begin();  
  // for debugging, wait until a serial console is connected
  Serial.begin(9600);
  delay(4000);
  while(!Serial);
  Serial.print("Initializing the bridge...");
  Bridge.begin();
  Serial.println("Done");
  // Set up digital inputs to monitor
  pinMode(digital7, INPUT);
  pinMode(digital8, INPUT);
}

// for RTC
// Convert normal decimal numbers to binary coded decimal
byte decToBcd(byte val)
{
  return ( (val/10*16) + (val%10) );
}

// Convert binary coded decimal to normal decimal numbers
byte bcdToDec(byte val)
{
  return ( (val/16*10) + (val%16) );
}

void readDS3232time(byte *second, 
byte *minute, 
byte *hour, 
byte *dayOfWeek, 
byte *dayOfMonth, 
byte *month, 
byte *year)
{
  Wire.beginTransmission(DS3232_I2C_ADDRESS);
  Wire.write(0); // set DS3232 register pointer to 00h
  Wire.endTransmission();  
  Wire.requestFrom(DS3232_I2C_ADDRESS, 7); // request 7 bytes of data from DS3232 starting from register 00h
  // A few of these need masks because certain bits are control bits
  *second     = bcdToDec(Wire.read() & 0x7f);
  *minute     = bcdToDec(Wire.read());
  *hour       = bcdToDec(Wire.read() & 0x3f);  // Need to change this if 12 hour am/pm
  *dayOfWeek  = bcdToDec(Wire.read());
  *dayOfMonth = bcdToDec(Wire.read());
  *month      = bcdToDec(Wire.read());
  *year       = bcdToDec(Wire.read());
}

void setDS3232time(byte second, byte minute, byte hour, byte dayOfWeek, byte dayOfMonth, byte month, byte year)
// sets time and date data to DS3232
{
  Wire.beginTransmission(DS3232_I2C_ADDRESS);  
  Wire.write(0); // sends 00h - seconds register
  Wire.write(decToBcd(second));     // set seconds
  Wire.write(decToBcd(minute));     // set minutes
  Wire.write(decToBcd(hour));       // set hours
  Wire.write(decToBcd(dayOfWeek));  // set day of week (1=Sunday, 7=Saturday)
  Wire.write(decToBcd(dayOfMonth)); // set date (1~31)
  Wire.write(decToBcd(month));      // set month
  Wire.write(decToBcd(year));       // set year (0~99)
  Wire.endTransmission();
}

void loop()
{
  // get the number of milliseconds this sketch has been running
  unsigned long now = millis();

  // run again if it's been 60 seconds since we last ran
  if (now - lastRun >= RUN_INTERVAL_MILLIS) {

    // remember 'now' as the last time we ran the choreo
    lastRun = now;
    Serial.println("Getting sensor values...");
    // get the values from A0 to A3 and D7, D8
    analog0 = analogRead(0);
    analog1 = analogRead(1);
    analog2 = analogRead(2);
    analog3 = analogRead(3);
    d7 = digitalRead(digital7);
    d8 = digitalRead(digital8);

    Serial.println("Appending value to spreadsheet...");
    // we need a Process object to send a Choreo request to Temboo
    TembooChoreo AppendRowChoreo;

    // invoke the Temboo client
    // NOTE that the client must be reinvoked and repopulated with
    // appropriate arguments each time its run() method is called.
    AppendRowChoreo.begin();

    // set Temboo account credentials
    AppendRowChoreo.setAccountName(TEMBOO_ACCOUNT);
    AppendRowChoreo.setAppKeyName(TEMBOO_APP_KEY_NAME);
    AppendRowChoreo.setAppKey(TEMBOO_APP_KEY);

    // identify the Temboo Library choreo to run (Google > Spreadsheets > AppendRow)
    AppendRowChoreo.setChoreo("/Library/Google/Spreadsheets/AppendRow");
    // your Google username (usually your email address)
    AppendRowChoreo.addInput("Username", GOOGLE_USERNAME);
    // your Google account password
    AppendRowChoreo.addInput("Password", GOOGLE_PASSWORD);
    // the title of the spreadsheet you want to append to
    AppendRowChoreo.addInput("SpreadsheetTitle", SPREADSHEET_TITLE);

    // get time and date from RTC
    readDS3232time(&second, &minute, &hour, &dayOfWeek, &dayOfMonth, &month, &year);

    // smoosh all the sensor, date and time data into a String
    // CSV creation starts here!
    String rowData(analog0);
    rowData += ",";
    rowData += analog1;
    rowData += ",";
    rowData += analog2;
    rowData += ",";
    rowData += analog3;
    rowData += ",";
    rowData += d7;
    rowData += ",";
    rowData += d8;    
    rowData += ",";
    // insert date
    rowData += dayOfMonth; 
    rowData += "/";
    rowData += month; 
    rowData += "/20";
    rowData += year; 
    rowData += ",";    
    // insert time    
    rowData += hour;  
    if (minute<10)
    {
        rowData += "0";  
    }    
    rowData += minute; 
    rowData += "."; 
    if (second<10)
    {
        rowData += "0";  
    }    
    rowData += second; 
    rowData += "h";     

    // add the RowData input item
    AppendRowChoreo.addInput("RowData", rowData);

    // run the Choreo and wait for the results
    // The return code (returnCode) will indicate success or failure 
    unsigned int returnCode = AppendRowChoreo.run();

    // return code of zero (0) means success
    if (returnCode == 0) {
      Serial.println("Success! Appended " + rowData);
      Serial.println("");
    } else {
      // return code of anything other than zero means failure  
      // read and display any error messages
      while (AppendRowChoreo.available()) {
        char c = AppendRowChoreo.read();
        Serial.print(c);
      }
    }
    AppendRowChoreo.close();
  }
}

… which in our example resulted with the following:

… and here is a video that shows how the spreadsheet updates in real time across multiple devices:

 Conclusion

It’s no secret that the Yún isn’t the cheapest devleopment board around, however the ease of use as demonstrated in this tutorial shows that the time saved in setup and application is more than worth the purchase price of the board and extra Temboo credits if required.

And if you’re interested in learning more about Arduino, or want to introduce someone else to the interesting world of Arduino – check out my book (now in a third printing!) “Arduino Workshop” from No Starch Press.

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitter, Google+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

The post Tutorial – Google Docs and the Arduino Yún appeared first on tronixstuff.

Tronixstuff 11 Nov 06:35

Project – LED Cube Spectrum Analyzer

Introduction

A few weeks ago I was asked about creating a musical-effect display with an RGB LED cube kit from Freetronics, and with a little work this was certainly possible using the MSGEQ7 spectrum analyser IC. In this project we’ll create a small add-on PCB containing the spectrum analyser circuit and show how it can drive the RGB LED cube kit.

Assumed knowledge

To save repeating myself, please familiarise yourself with the MSGEQ7 spectrum aanalyserIC in Chapter 48 of our Arduino tutorials. And learn more about the LED cube from our review and the product page.

You can get MSGEQ7 ICs from various sources, however they had varying results. We now recommend using the neat module from Tronixlabs.

The circuit

The LED cube already has an Arduino Leonardo-compatible built in to the main PCB, so all you need to do is build a small circuit that contains the spectrum analyzer which connects to the I/O pins on the cube PCB and also has audio input and output connections. First, consider the schematic:

For the purposes of this project our spectrum analyser will only display the results from one channel of audio – if you want stereo, you’ll need two! And note that the strobe, reset and DCOUT pins on the MSGEQ7 are labelled with the connections to the cube PCB. Furthermore the pinouts for the MSGEQ7 don’t match the physical reality – here are the pinouts from the MSGEQ7 data sheet (.pdf):

The circuit itself will be quite small and fit on a small amount of stripboard or veroboard. There is plenty of room underneath the cube to fit the circuit if so desired:

With a few moments you should be able to trace out your circuit to match the board type you have, remember to double-check before soldering. You will also need to connect the audio in point after the 1000 pF capacitor to a source of audio, and also pass it through so you can connect powered speakers, headphones, etc.

One method of doing so would be to cut up a male-female audio extension lead, and connect the shield to the GND of the circuit, and the signal line to the audio input on the circuit. Or if you have the parts handy and some shielded cable, just make your own input and output leads:

Be sure to test for shorts between the signal and shield before soldering to the circuit board. When finished, you should have something neat that you can hide under the cube or elsewhere:

Double-check your soldering for shorts and your board plan, then fit to the cube along with the audio source and speakers (etc).

Arduino Sketch

The sketch has two main functions – the first is to capture the levels from the MSGEQ7 and put the values for each frequency band into an array, and the second function is to turn on LEDs that represent the level for each band. If you’ve been paying attention you may be wondering how we can represent seven frequency bands with a 4x4x4 LED cube. Simple – by rotating the cube 45 degrees you can see seven vertical columns of LEDs:

So when looking from the angle as shown above, you have seven vertical columns, each with four levels of LEDs. Thus the strength of each frequency can be broken down into four levels, and then the appropriate LEDs turned on.

After this is done for each band, all the LEDs are turned off and the process repeats. For the sake of simplicity I’ve used the cube’s Arduino library to activate the LEDs, which also makes the sketch easier to fathom. The first example sketch only uses one colour:

// Freetronics CUBE4: and MSGEQ7 spectrum analyser
// MSGEQ7 strobe on A4, reset on D5, signal into A0

#include "SPI.h"
#include "Cube.h"
Cube cube;

int res = 5; // reset pins on D5
int left[7]; // store band values in these arrays
int band;

void setup()
{
  pinMode(res, OUTPUT); // reset
  pinMode(A4, OUTPUT); // strobe
  digitalWrite(res,LOW); 
  digitalWrite(A4,HIGH); 
  cube.begin(-1, 115200);
  Serial.begin(9600);
}

void readMSGEQ7()
// Function to read 7 band equalizers
{
  digitalWrite(res, HIGH);
  digitalWrite(res, LOW);
  for(band=0; band <7; band++)
  {
    digitalWrite(A4,LOW); // strobe pin on the shield - kicks the IC up to the next band 
    delayMicroseconds(30); // 
    left[band] = analogRead(0); // store band reading
    digitalWrite(A4,HIGH); 
  }
}

void loop()
{
  readMSGEQ7();

  for (band = 0; band < 7; band++)
  {
    // div each band strength into four layers, each band then one of the odd diagonals 

    // band one ~ 63 Hz
    if (left[0]>=768) { 
      cube.set(3,3,3, BLUE); 
    } 
    else       
      if (left[0]>=512) { 
      cube.set(3,3,2, BLUE); 
    } 
    else   
      if (left[0]>=256) { 
      cube.set(3,3,1, BLUE); 
    } 
    else       
      if (left[0]>=0) { 
      cube.set(3,3,0, BLUE); 
    } 

    // band two ~ 160 Hz
    if (left[1]>=768) 
    { 
      cube.set(3,2,3, BLUE); 
      cube.set(2,3,3, BLUE);      
    }  
    else
      if (left[1]>=512) 
      { 
        cube.set(3,2,2, BLUE); 
        cube.set(2,3,2, BLUE);      
      } 
      else   
        if (left[1]>=256) 
      { 
        cube.set(3,2,1, BLUE); 
        cube.set(2,3,1, BLUE);      
      } 
      else   
        if (left[1]>=0) 
      { 
        cube.set(3,2,0, BLUE); 
        cube.set(2,3,0, BLUE);      
      } 

    // band three ~ 400 Hz
    if (left[2]>=768) 
    { 
      cube.set(3,1,3, BLUE); 
      cube.set(2,2,3, BLUE);      
      cube.set(1,3,3, BLUE);            
    }  
    else
      if (left[2]>=512) 
      { 
        cube.set(3,1,2, BLUE); 
        cube.set(2,2,2, BLUE);      
        cube.set(1,3,2, BLUE);            
      } 
      else   
        if (left[2]>=256) 
      { 
        cube.set(3,1,1, BLUE); 
        cube.set(2,2,1, BLUE);      
        cube.set(1,3,1, BLUE);            
      } 
      else   
        if (left[2]>=0) 
      { 
        cube.set(3,1,0, BLUE); 
        cube.set(2,2,0, BLUE);      
        cube.set(1,3,0, BLUE);            
      } 

    // band four ~ 1 kHz
    if (left[3]>=768) 
    { 
      cube.set(3,0,3, BLUE); 
      cube.set(2,1,3, BLUE);      
      cube.set(1,2,3, BLUE);            
      cube.set(0,3,3, BLUE);                  
    }  
    else
      if (left[3]>=512) 
      { 
        cube.set(3,0,2, BLUE); 
        cube.set(2,1,2, BLUE);      
        cube.set(1,2,2, BLUE);            
        cube.set(0,3,2, BLUE);                        
      } 
      else   
        if (left[3]>=256) 
      { 
        cube.set(3,0,1, BLUE); 
        cube.set(2,1,1, BLUE);      
        cube.set(1,2,1, BLUE);      
        cube.set(0,3,1, BLUE);                        
      } 
      else   
        if (left[3]>=0) 
      { 
        cube.set(3,0,0, BLUE); 
        cube.set(2,1,0, BLUE);      
        cube.set(1,2,0, BLUE);            
        cube.set(0,3,0, BLUE);                        
      } 

    // band five  ~ 2.5 kHz
    if (left[4]>=768) 
    { 
      cube.set(2,0,3, BLUE); 
      cube.set(1,1,3, BLUE);      
      cube.set(0,2,3, BLUE);            
    }  
    else
      if (left[4]>=512) 
      { 
        cube.set(2,0,2, BLUE); 
        cube.set(1,1,2, BLUE);      
        cube.set(0,2,2, BLUE);            
      } 
      else   
        if (left[4]>=256) 
      { 
        cube.set(2,0,1, BLUE); 
        cube.set(1,1,1, BLUE);      
        cube.set(0,2,1, BLUE);      
      } 
      else   
        if (left[4]>=0) 
      { 
        cube.set(2,0,0, BLUE); 
        cube.set(1,1,0, BLUE);      
        cube.set(0,2,0, BLUE);            
      } 

    // band six   ~ 6.25 kHz
    if (left[5]>=768) 
    { 
      cube.set(1,0,3, BLUE); 
      cube.set(0,1,3, BLUE);      
    }  
    else
      if (left[5]>=512) 
      { 
        cube.set(1,0,2, BLUE); 
        cube.set(0,1,2, BLUE);      
      } 
      else   
        if (left[5]>=256) 
      { 
        cube.set(1,0,1, BLUE); 
        cube.set(0,1,1, BLUE);      
      } 
      else   
        if (left[5]>=0) 
      { 
        cube.set(1,0,0, BLUE); 
        cube.set(0,1,0, BLUE);      
      } 

    // band seven  ~ 16 kHz
    if (left[6]>=768) 
    { 
      cube.set(0,0,3, BLUE); 
    }  
    else
      if (left[6]>=512) 
      { 
        cube.set(0,0,2, BLUE); 
      } 
      else   
        if (left[6]>=256) 
      { 
        cube.set(0,0,1, BLUE); 
      } 
      else   
        if (left[6]>=0) 
      { 
        cube.set(0,0,0, BLUE); 
      } 
  }
  // now clear the CUBE, or if that's too slow - repeat the process but turn LEDs off
  cube.all(BLACK);
}

… and a quick video demonstration:

For a second example, we’ve used various colours:

// Freetronics CUBE4: and MSGEQ7 spectrum analyser
// MSGEQ7 strobe on A4, reset on D5, signal into A0
// now in colour!

#include "SPI.h"
#include "Cube.h"
Cube cube;

int res = 5; // reset pins on D5
int left[7]; // store band values in these arrays
int band;
int additional=0;

void setup()
{
  pinMode(res, OUTPUT); // reset
  pinMode(A4, OUTPUT); // strobe
  digitalWrite(res,LOW); 
  digitalWrite(A4,HIGH); 
  cube.begin(-1, 115200);
  Serial.begin(9600);
}

void readMSGEQ7()
// Function to read 7 band equalizers
{
  digitalWrite(res, HIGH);
  digitalWrite(res, LOW);
  for(band=0; band <7; band++)
  {
    digitalWrite(A4,LOW); // strobe pin on the shield - kicks the IC up to the next band 
    delayMicroseconds(30); // 
    left[band] = analogRead(0) + additional; // store band reading
    digitalWrite(A4,HIGH); 
  }
}

void loop()
{
  readMSGEQ7();

  for (band = 0; band < 7; band++)
  {
    // div each band strength into four layers, each band then one of the odd diagonals 

    // band one ~ 63 Hz
    if (left[0]>=768) { 
      cube.set(3,3,3, RED); 
    } 
    else       
      if (left[0]>=512) { 
      cube.set(3,3,2, YELLOW); 
    } 
    else   
      if (left[0]>=256) { 
      cube.set(3,3,1, YELLOW); 
    } 
    else       
      if (left[0]>=0) { 
      cube.set(3,3,0, BLUE); 
    } 

    // band two ~ 160 Hz
    if (left[1]>=768) 
    { 
      cube.set(3,2,3, RED); 
      cube.set(2,3,3, RED);      
    }  
    else
      if (left[1]>=512) 
      { 
        cube.set(3,2,2, YELLOW); 
        cube.set(2,3,2, YELLOW);      
      } 
      else   
        if (left[1]>=256) 
      { 
        cube.set(3,2,1, YELLOW); 
        cube.set(2,3,1, YELLOW);      
      } 
      else   
        if (left[1]>=0) 
      { 
        cube.set(3,2,0, BLUE); 
        cube.set(2,3,0, BLUE);      
      } 

    // band three ~ 400 Hz
    if (left[2]>=768) 
    { 
      cube.set(3,1,3, RED); 
      cube.set(2,2,3, RED);      
      cube.set(1,3,3, RED);            
    }  
    else
      if (left[2]>=512) 
      { 
        cube.set(3,1,2, YELLOW); 
        cube.set(2,2,2, YELLOW);      
        cube.set(1,3,2, YELLOW);            
      } 
      else   
        if (left[2]>=256) 
      { 
        cube.set(3,1,1, YELLOW); 
        cube.set(2,2,1, YELLOW);      
        cube.set(1,3,1, YELLOW);            
      } 
      else   
        if (left[2]>=0) 
      { 
        cube.set(3,1,0, BLUE); 
        cube.set(2,2,0, BLUE);      
        cube.set(1,3,0, BLUE);            
      } 

    // band four ~ 1 kHz
    if (left[3]>=768) 
    { 
      cube.set(3,0,3, RED); 
      cube.set(2,1,3, RED);      
      cube.set(1,2,3, RED);            
      cube.set(0,3,3, RED);                  
    }  
    else
      if (left[3]>=512) 
      { 
        cube.set(3,0,2, YELLOW); 
        cube.set(2,1,2, YELLOW);      
        cube.set(1,2,2, YELLOW);            
        cube.set(0,3,2, YELLOW);                        
      } 
      else   
        if (left[3]>=256) 
      { 
        cube.set(3,0,1, YELLOW); 
        cube.set(2,1,1, YELLOW);      
        cube.set(1,2,1, YELLOW);      
        cube.set(0,3,1, YELLOW);                        
      } 
      else   
        if (left[3]>=0) 
      { 
        cube.set(3,0,0, BLUE); 
        cube.set(2,1,0, BLUE);      
        cube.set(1,2,0, BLUE);            
        cube.set(0,3,0, BLUE);                        
      } 

    // band five  ~ 2.5 kHz
    if (left[4]>=768) 
    { 
      cube.set(2,0,3, RED); 
      cube.set(1,1,3, RED);      
      cube.set(0,2,3, RED);            
    }  
    else
      if (left[4]>=512) 
      { 
        cube.set(2,0,2, YELLOW); 
        cube.set(1,1,2, YELLOW);      
        cube.set(0,2,2, YELLOW);            
      } 
      else   
        if (left[4]>=256) 
      { 
        cube.set(2,0,1, YELLOW); 
        cube.set(1,1,1, YELLOW);      
        cube.set(0,2,1, YELLOW);      
      } 
      else   
        if (left[4]>=0) 
      { 
        cube.set(2,0,0, BLUE); 
        cube.set(1,1,0, BLUE);      
        cube.set(0,2,0, BLUE);            
      } 

    // band six   ~ 6.25 kHz
    if (left[5]>=768) 
    { 
      cube.set(1,0,3, RED); 
      cube.set(0,1,3, RED);      
    }  
    else
      if (left[5]>=512) 
      { 
        cube.set(1,0,2, YELLOW); 
        cube.set(0,1,2, YELLOW);      
      } 
      else   
        if (left[5]>=256) 
      { 
        cube.set(1,0,1, YELLOW); 
        cube.set(0,1,1, YELLOW);      
      } 
      else   
        if (left[5]>=0) 
      { 
        cube.set(1,0,0, BLUE); 
        cube.set(0,1,0, BLUE);      
      } 

    // band seven  ~ 16 kHz
    if (left[6]>=768) 
    { 
      cube.set(0,0,3, RED); 
    }  
    else
      if (left[6]>=512) 
      { 
        cube.set(0,0,2, YELLOW); 
      } 
      else   
        if (left[6]>=256) 
      { 
        cube.set(0,0,1, YELLOW); 
      } 
      else   
        if (left[6]>=0) 
      { 
        cube.set(0,0,0, BLUE); 
      } 
  }
  // now clear the CUBE, or if that's too slow - repeat the process but turn LEDs off
  cube.all(BLACK);
}

… and the second video demonstration:

A little bit of noise comes through into the spectrum analyser, most likely due to the fact that the entire thing is unshielded. The previous prototype used the Arduino shield from the tutorial which didn’t have this problem, so if you’re keen perhaps make your own custom PCB for this project.

xxxxxxx

Conclusion

Well that was something different and I hope you enjoyed it, and can find use for the circuit. That MSGEQ7 is a handy IC and with some imagination you can create a variety of musically-influenced displays. And if you enjoyed this article, or want to introduce someone else to the interesting world of Arduino – check out my book (now in a fourth printing!) “Arduino Workshop”.

Have fun and keep checking into tronixstuff.com. Why not follow things on twitter, Google+, subscribe  for email updates or RSS using the links on the right-hand column, or join our forum – dedicated to the projects and related items on this website.

The post Project – LED Cube Spectrum Analyzer appeared first on tronixstuff.

Tutorial – twitter and the Arduino Yún

Introduction

After spending almost $100 on an Arduino Yún to see what the fuss was about, it seemed like a good idea to find and demonstrate some uses for it. So in this article we’ll examine how your Yún can send a tweet using some simple example sketches – and the first of several Arduino Yún-specific tutorials.

Getting Started

If you haven’t already done so, ensure your Arduino Yún can connect to your network via WiFi or cable – and get a Temboo account (we run through this here). And you need (at the time of writing) IDE version 1.5.4 which can be downloaded from the Arduino website. Finally, if you don’t have a twitter account – go get one.

Sending a tweet from your Yún

Thanks to Arduino and Temboo, 99% of the work is already done for you. To send a tweet requires the Arduino sketch, a header file with your Temboo account details, and also the need to register an application in the twitter development console.

Don’t panic, just follow the “Get Set Up” instructions from the following page. When you do – make sure you’re logged into the Temboo website, as it will then populate the header file with your Temboo details for you. During the twitter application stage, don’t forget to save your OAuth settings which will appear in the “OAuth Tool” tab in the twitter developer page, for example:

… as they are copied into every sketch starting from the line:

const String TWITTER_ACCESS_TOKEN =

When you save the sketch, make sure you place the header file with the name TembooAccount.h in the same folder as your sketch. You know this has been successful when opening the sketch, as you will see the header file in a second tab, for example:

Finally, if you’re sharing code with others, remove your OAuth and TembooAccount.h details otherwise they can send tweets on your behalf.

OK – enough warnings. If you’ve successfully created your Temboo account, got your twitter OAuth details, fed them all into the sketch and header file, then saved (!) and uploaded your sketch to the Arduino Yún – a short tweet will appear on your timeline, for example:

If nothing appears on your twitter feed, open the serial monitor in the IDE and see what messages appear. It will feed back to you the error message from twitter, which generally indicates the problem.

Moving on, let’s examine how to send tweets with your own information. In the following example sketch we send the value resulting from analogRead(0) and text combined together in one line. Don’t forget twitter messages (tweets) have a maximum length of 140 characters. We’ve moved all the tweet-sending into one function tweet(), which you can then call from your sketch when required – upon an event and so on. The text and data to send is combined into a String in line 26:

#include <Bridge.h>
#include <Temboo.h>
#include "TembooAccount.h" // contains Temboo account information
                           // as described in the footer comment below

const String TWITTER_ACCESS_TOKEN = "aaaa";
const String TWITTER_ACCESS_TOKEN_SECRET = "bbbb";
const String TWITTER_CONSUMER_KEY = "ccccc";
const String TWITTER_CONSUMER_SECRET = "dddd";

int analogZero;

void setup() 
{
  Serial.begin(9600);
  delay(4000);
  while(!Serial);
  Bridge.begin();
}

void tweet()
{
    Serial.println("Running tweet() function");

    // define the text of the tweet we want to send
    String tweetText("The value of A0 is " + String(analogZero) + ". Hooray for twitter");

    TembooChoreo StatusesUpdateChoreo;
    // invoke the Temboo client
    // NOTE that the client must be reinvoked, and repopulated with
    // appropriate arguments, each time its run() method is called.
    StatusesUpdateChoreo.begin();
    // set Temboo account credentials
    StatusesUpdateChoreo.setAccountName(TEMBOO_ACCOUNT);
    StatusesUpdateChoreo.setAppKeyName(TEMBOO_APP_KEY_NAME);
    StatusesUpdateChoreo.setAppKey(TEMBOO_APP_KEY);
    // identify the Temboo Library choreo to run (Twitter > Tweets > StatusesUpdate)
    StatusesUpdateChoreo.setChoreo("/Library/Twitter/Tweets/StatusesUpdate");
    // add the Twitter account information
    StatusesUpdateChoreo.addInput("AccessToken", TWITTER_ACCESS_TOKEN);
    StatusesUpdateChoreo.addInput("AccessTokenSecret", TWITTER_ACCESS_TOKEN_SECRET);
    StatusesUpdateChoreo.addInput("ConsumerKey", TWITTER_CONSUMER_KEY);    
    StatusesUpdateChoreo.addInput("ConsumerSecret", TWITTER_CONSUMER_SECRET);
    // and the tweet we want to send
    StatusesUpdateChoreo.addInput("StatusUpdate", tweetText);
    // tell the Process to run and wait for the results. The 
    // return code (returnCode) will tell us whether the Temboo client 
    // was able to send our request to the Temboo servers
    unsigned int returnCode = StatusesUpdateChoreo.run();
    // a return code of zero (0) means everything worked
    if (returnCode == 0) {
        Serial.println("Success! Tweet sent!");
    } else {
      // a non-zero return code means there was an error
      // read and print the error message
      while (StatusesUpdateChoreo.available()) {
        char c = StatusesUpdateChoreo.read();
        Serial.print(c);
      }
    } 
    StatusesUpdateChoreo.close();
    // do nothing for the next 90 seconds
    Serial.println("Waiting...");
    delay(90000);
}

void loop()
{
  // get some data from A0. 
  analogZero=analogRead(0);
  tweet();
  do {} while (1); // do nothing
}

Which results with the following example tweet:

With the previous example sketch you can build your own functionality around the tweet() function to send data when required. Recall that the data to send as a tweet is combined into a String at line 26.

Please note that you can’t blast out tweets like a machine, for two reasons – one, twitter doesn’t like rapid automated tweeting – and two, you only get 1000 free calls on your Temboo account per month. If you need more, the account needs to be upgraded at a cost.

Conclusion

Well the Yún gives us another way to send data out via twitter. It wasn’t the cheapest way of doing so, however it was quite simple. And thus the trade-off with the Arduino platform – simplicity vs. price. If there is demand, we’ll examine more connected functions with the Yún.

And if you’re interested in learning more about Arduino, or want to introduce someone else to the interesting world of Arduino – check out my book (now in a third printing!) “Arduino Workshop” from No Starch Press.

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitter, Google+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

The post Tutorial – twitter and the Arduino Yún appeared first on tronixstuff.

Tronixstuff 29 Oct 05:40

Review – “Ardublock” graphical programming for Arduino

Introduction

After helping many people get started with the world of Arduino and electronics,  we still find a small percentage of people who are turned off by the concept of programming or have trouble breaking larger tasks into smaller ones with regards to writing algorithms for their code/sketch.

So after being introduced to a new graphical programming tool called “Ardublock“, we were excited about the possibilities wanted to share it with our readers. Ardublock provides a truly graphical and non-coding solution to controlling an Arduino, that is an open-source product and thus free to download and try for yourself.

Installation

Ardublock is a Java application that runs from inside the Arduino IDE, which can be downloaded from here. It’s only one file, that needs to be placed in a new folder in the Arduino IDE. The folder names must be the same as shown below:

Once you’ve copied the file, simply open the Arduino IDE and select Ardublock from the Tools menu:

From which point a new window appears – the Ardublock “development environment”:

 Using Ardublock

It’s quite simple – you simply select the required function from the menu on the left and drag it into the large area on the right. For a quick example where we blink the onboard LED on and off – watch the following video:

 

The following image is the screen capture of the program from the video:

As you can see the “blocks” just fit together, and parameters can be changed with the right mouse button. After a few moments experimenting with the Ardublock software you will have the hang of it in no time at all.

And thus you can demonstrate it to other people and show them how easy it is. And there is much more than just digital output controls, all the functions you’re used to including I2C, variables, constants, servos, tone and more are available.

The only technical thing you need to demonstrate is that the Arduino IDE needs to stay open in the background – as once you have finished creating your program, Ardublock creates the required real Arduino sketch back in the IDE and uploads it to the board.

This is also a neat function – the user can then compare their Ardublock program against the actual sketch, and hopefully after a short duration the user will have the confidence to move on with normal coding.

Conclusion

Ardublock provides a very simple method of controlling an Arduino, and makes a great starting point for teaching the coding-averse, very young people or the cognitively-challenged. It’s open source, integrates well with the official IDE and works as described – so give it a go.

And if you enjoyed this review, or want to introduce someone else to the interesting world of Arduino – check out my book (now in a third printing!) “Arduino Workshop” from No Starch Press.

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitter, Google+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

The post Review – “Ardublock” graphical programming for Arduino appeared first on tronixstuff.

Tutorial – Arduino and the TLC5940 PWM LED Driver IC

Use the Texas Instruments TLC5940 16-Channel LED Driver IC with Arduino in Chapter 57 of our Arduino Tutorials. The first chapter is here, the complete series is detailed here.

Introduction

Today we are going to examine the Texas Instruments TLC5940 16-channel LED driver IC. Our reason for doing this is to demonstrate another, easier way of driving many LEDs – and also servos.  First up, here is a few examples of the TLC5940

The TLC5940 is available in the DIP version above, and also surface-mount. It really is a convenient part, allowing you to adjust the brightness of sixteen individual LEDs via PWM (pulse-width modulation) – and you can also daisy-chain more than one TLC5940 to control even more.

During this tutorial we’ll explain how to control one or more TLC5940 ICs with LEDs and also look at controlling servos. At this point, please download a copy of the TLC5940_data_sheet (.pdf) as you will refer to it through this process. Furthermore, please download and install the TLC5940 Arduino library by Alex Leone which can be found here. If you’re not sure how to install a library, click here.

Build a TLC5940 demonstration circuit

The following circuit is the minimum required to control sixteen LEDs from your Arduino or compatible. You can use it to experiment with various functions and get an idea of what is possible. You will need:

  • An Arduino Uno or compatible board
  • 16 normal, everyday LEDs that can have a forward current of up to 20 mA
  • a 2 kΩ resistor (give or take 10%)
  • a 0.1uF ceramic and a 4.7uF electrolytic capacitor

Take note of the LED orientation – and remember the TLC5940 is a common-anode LED driver – so all the LED anodes are connected together and then to 5V:

For this particular circuit, you won’t need an external 5V power supply – however you may need one in the future. The purpose of the resistor is to control the amount of current that can flow through the LEDs. The required resistor value is calculated with the following formula:

R = 39.06 / Imax

where R (in Ohms)  is the resistor value and Imax (in Amps) is the maximum amount of current you want to flow through the LEDs. For example, if you have LEDs with a 20 mA forward current – the resistor calculation would be:

R = 39.06 / 0.02 = 1803 Ohms.

Once you have the circuit assembled – open up the Arduino IDE and upload the sketch BasicUse.pde  which is in the example folder for the TLC5940 library. You should be presented with output similar to what is shown in the following video:

Controlling the TLC5940

Now that the circuit works, how do we control the TLC5940? First, the mandatory functions – include the library at the start of the sketch with:

#include "Tlc5940.h"

and then initialise the library by placing the following into void setup():

Tlc.init(x);

x is an optional parameter – if you want to set all the channels to a certain brightness as soon as the sketch starts, you can insert a value between 0 and 4095 for x in the Tlc.init() function.

Now to turn a channel/LED on or off. Each channel is numbered from 0 to 15, and each channel’s brightness can be adjusted between 0 and 4095.

This is a two-part process…

First – use one or more of the following functions to set up the required channels and respective brightness (PWM level):

Tlc.set(channel, brightness);

For example, if you wanted to have the first three channels on at full brightness, use:

Tlc.set(0, 4095);
Tlc.set(1, 4095);
Tlc.set(2, 4095);

The second part is to use the following to update the TLC5940 with the required instructions from part one:

Tlc.update();

If you want to turn off all channels at once, simply use:

Tlc.clear();

You don’t need to call a TLC.update() after the clear function. The following is a quick example sketch that sets the brightness/PWM values of all the channels to different levels:

#include "Tlc5940.h"
void setup()
{
  Tlc.init(0); // initialise TLC5940 and set all channels off
}

void loop()
{
  for (int i = 0; i < 16; i++)
  {
    Tlc.set(i, 1023);
  }
  Tlc.update();
  delay(1000);
  for (int i = 0; i < 16; i++)
  {
    Tlc.set(i, 2046);
  }
  Tlc.update();
  delay(1000);
  for (int i = 0; i < 16; i++)
  {
    Tlc.set(i, 3069);
  }
  Tlc.update();
  delay(1000);
  for (int i = 0; i < 16; i++)
  {
    Tlc.set(i, 4095);
  }
  Tlc.update();
  delay(1000);
}

and the sketch in action:

The ability to control individual brightness for each channel/LED can also be useful when controlling RGB LEDs – you can then easily select required colours via different brightness levels for each element.

Using two or more TLC5940s

You can daisy-chain quite a few TLC5940s together to control more LEDs. First – wire up the next TLC5940 to the Arduino as shown in the demonstration circuit – except connect the SOUT pin (17) of the first TLC5940 to the SIN pin (26) of the second TLC5940 – as the data travels from the Arduino, through the first TLC5940 to the second and so on. Then repeat the process if you have a third, etc. Don’t forget the resisotr that sets the current!

Next, open the file tlc_config.h located in the TLC5940 library folder. Change the value of NUM_TLCS to the number of TLC5940s you have connected together, then save the file and also delete the file Tlc5940.o also located in the same folder. Finally restart the IDE. You can then refer to the channels of the second and further TLC5940 sequentially from the first. That is, the first is 0~15, the second is 16~29, and so on.

Controlling servos with the TLC5940

As the TLC5940 generates PWM (pulse-width modulation) output, it’s great for driving servos as well. Just like LEDs – you can control up to sixteen at once. Ideal for creating spider-like robots, strange clocks or making some noise. When choosing your servo, ensure that it doesn’t draw more than 120 mA when operating (the maximum current per channel) and also heed the “Managing current and heat” section at the end of this tutorial. And use external power with servos, don’t rely on the Arduino’s 5V line.

To connect a servo is simple – the GND line connects to GND, the 5V (or supply voltage lead) connects to your 5v (or other suitable supply) and the servo control pin connects to one of the TLC5940’s outputs. Finally – and this is important – connect a 2.2kΩ resistor between the TLC5940 output pin(s) being used and 5V.

Controlling a servo isn’t that different to an LED. You need the first two lines at the start of the sketch:

#include "Tlc5940.h"
#include "tlc_servos.h"

then the following in void setup():

tlc_initServos();

Next, use the following function to select which servo (channel) to operate and the required angle (angle):

tlc_setServo(channel, angle);

Just like the LEDs you can bunch a few of these together, and then execute the command with:

Tlc.update();

So let’s see all that in action. The following example sketch sweeps four servos across 90 degrees:

#include "Tlc5940.h"
#include "tlc_servos.h"

void setup()
{
  tlc_initServos();  // Note: this will drop the PWM freqency down to 50Hz.
}

void loop()
{
  for (int angle = 0; angle < 90; angle++) {
    tlc_setServo(0, angle);
    tlc_setServo(1, angle);
    tlc_setServo(2, angle);
    tlc_setServo(3, angle);    
    Tlc.update();
    delay(5);
  }
  for (int angle = 90; angle >= 0; angle--) {
    tlc_setServo(0, angle);
    tlc_setServo(1, angle);
    tlc_setServo(2, angle);
    tlc_setServo(3, angle);    
    Tlc.update();
    delay(5);
  }
}

And the following video captures those four servos in action:

 

If you servos are not rotating to the correct angle – for example you ask for 180 degrees and they only rotate to 90 or thereabouts, a little extra work is required. You need to open the tlc_servos.h file located in the TLC5940 Arduino library folder and experiment with the values for SERVO_MIN_WIDTH and SERVO_MAX_WIDTH. For example change SERVO_MIN_WIDTH from 200 to 203 and SERVO_MAX_WIDTH from 400 to 560.

Managing current and heat 

As mentioned earlier, the TLC5940 can handle a maximum of 120 mA per channel. After some experimenting you may notice that the TLC5940 does get warm – and that’s ok. However there is a maximum limit to the amount of power that can be dissipated before destroying the part. If you are just using normal garden-variety LEDs or smaller servos, power won’t be a problem. However if you’re planning on using the TLC5940 to the max – please review the notes provided by the library authors.

Conclusion

Once again you’re on your way to controlling an incredibly useful part with your Arduino. Now with some imagination you can create all sorts of visual displays or have fun with many servos. And if you enjoyed the tutorial, or want to introduce someone else to the interesting world of Arduino – check out my book (now in a third printing!) “Arduino Workshop” from No Starch Press.

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitter, Google+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

The post Tutorial – Arduino and the TLC5940 PWM LED Driver IC appeared first on tronixstuff.

Tronixstuff 21 Oct 03:47

Tutorial – Arduino and the MAX7219 LED Display Driver IC

Use the Maxim MAX7219 LED display driver with Arduino in Chapter 56 of our Arduino Tutorials. The first chapter is here, the complete series is detailed here.

Update – 4/1/15 – This article is pending a re-write, please refrain from comments and questions until the new version is published. 

Introduction

Sooner or later Arduino enthusiasts and beginners alike will come across the MAX7219 IC. And for good reason, it’s a simple and somewhat inexpensive method of controlling 64 LEDs in either matrix or numeric display form. Furthermore they can be chained together to control two or more units for even more LEDs. Overall – they’re a lot of fun and can also be quite useful, so let’s get started.

Here’s an example of a MAX7219 and another IC which is a functional equivalent, the AS1107 from Austria Microsystems. You might not see the AS1107 around much, but it can be cheaper – so don’t be afraid to use that instead:

When shopping for MAX7219s you may notice the wild price fluctuations between various sellers. We’ve researched that and have a separate article for your consideration.

 At first glance you may think that it takes a lot of real estate, but it saves some as well. As mentioned earlier, the MAX7219 can completely control 64 individual LEDs – including maintaining equal brightness, and allowing you to adjust the brightness of the LEDs either with hardware or software (or both). It can refresh the LEDs at around 800 Hz, so no more flickering, uneven LED displays.

You can even switch the display off for power saving mode, and still send it data while it is off. And another good thing – when powered up, it keeps the LEDs off, so no wacky displays for the first seconds of operation. For more technical information, here is the data sheet: MAX7219.pdf. Now to put it to work for us – we’ll demonstrate using one or more 8 x 8 LED matrix displays, as well as 8 digits of 7-segment LED numbers.

Before continuing, download and install the LedControl Arduino library as it is essential for using the MAX7219.

Controlling LED matrix displays with the MAX7219

First of all, let’s examine the hardware side of things. Here is the pinout diagram for the MAX7219:

The MAX7219 drives eight LEDs at a time, and by rapidly switching banks of eight your eyes don’t see the changes. Wiring up a matrix is very simple – if you have a common matrix with the following schematic:

connect the MAX7219 pins labelled DP, A~F to the row pins respectively, and the MAX7219 pins labelled DIG0~7 to the column pins respectively. A total example circuit with the above matrix  is as follows:

The circuit is quite straight forward, except we have a resistor between 5V and MAX7219 pin 18. The MAX7219 is a constant-current LED driver, and the value of the resistor is used to set the current flow to the LEDs. Have a look at table eleven on page eleven of the data sheet:

You’ll need to know the voltage and forward current for your LED matrix or numeric display, then match the value on the table. E.g. if you have a 2V 20 mA LED, your resistor value will be 28kΩ (the values are in kΩ). Finally, the MAX7219 serial in, load and clock pins will go to Arduino digital pins which are specified in the sketch. We’ll get to that in the moment, but before that let’s return to the matrix modules.

In the last few months there has been a proliferation of inexpensive kits that contain a MAX7219 or equivalent, and an LED matrix. These are great for experimenting with and can save you a lot of work – some examples of which are shown below:

At the top is an example from ebay, and the pair on the bottom are the units from a recent kit review. We’ll use these for our demonstrations as well.

Now for the sketch. You need the following two lines at the beginning of the sketch:

#include "LedControl.h" 
LedControl lc=LedControl(12,11,10,1);

The first pulls in the library, and the second line sets up an instance to control. The four parameters are as follows:

  1. the digital pin connected to pin 1 of the MAX7219 (“data in”)
  2. the digital pin connected to pin 13 of the MAX7219 (“CLK or clock”)
  3. the digital pin connected to pin 12 of the MAX7219 (“LOAD”)
  4. The number of MAX7219s connected.

If you have more than one MAX7219, connect the DOUT (“data out”) pin of the first MAX7219 to pin 1 of the second, and so on. However the CLK and LOAD pins are all connected in parallel and then back to the Arduino.

Next, two more vital functions that you’d normally put in void setup():

lc.shutdown(0,false);
lc.setIntensity(0,8);

The first line above turns the LEDs connected to the MAX7219 on. If you set TRUE, you can send data to the MAX7219 but the LEDs will stay off. The second line adjusts the brightness of the LEDs in sixteen stages. For both of those functions (and all others from the LedControl) the first parameter is the number of the MAX7219 connected. If you have one, the parameter is zero… for two MAX7219s, it’s 1 and so on.

Finally, to turn an individual LED in the matrix on or off, use:

lc.setLed(0,col,row,true);

which turns on an LED positioned at col, row connected to MAX7219 #1. Change TRUE to FALSE to turn it off. These functions are demonstrated in the following sketch:

#include "LedControl.h" //  need the library
LedControl lc=LedControl(12,11,10,1); // 

// pin 12 is connected to the MAX7219 pin 1
// pin 11 is connected to the CLK pin 13
// pin 10 is connected to LOAD pin 12
// 1 as we are only using 1 MAX7219

void setup()
{
  // the zero refers to the MAX7219 number, it is zero for 1 chip
  lc.shutdown(0,false);// turn off power saving, enables display
  lc.setIntensity(0,8);// sets brightness (0~15 possible values)
  lc.clearDisplay(0);// clear screen
}
void loop()
{
  for (int row=0; row<8; row++)
  {
    for (int col=0; col<8; col++)
    {
      lc.setLed(0,col,row,true); // turns on LED at col, row
      delay(25);
    }
  }

  for (int row=0; row<8; row++)
  {
    for (int col=0; col<8; col++)
    {
      lc.setLed(0,col,row,false); // turns off LED at col, row
      delay(25);
    }
  }
}

And a quick video of the results:

How about controlling two MAX7219s? Or more? The hardware modifications are easy – connect the serial data out pin from your first MAX7219 to the data in pin on the second (and so on), and the LOAD and CLOCK pins from the first MAX7219 connect to the second (and so on). You will of course still need the 5V, GND, resistor, capacitors etc. for the second and subsequent MAX7219.

You will also need to make a few changes in your sketch. The first is to tell it how many MAX7219s you’re using in the following line:

LedControl lc=LedControl(12,11,10,X);

by replacing X with the quantity. Then whenever you’re using  a MAX7219 function, replace the (previously used) zero with the number of the MAX7219 you wish to address. They are numbered from zero upwards, with the MAX7219 directly connected to the Arduino as unit zero, then one etc. To demonstrate this, we replicate the previous example but with two MAX7219s:

#include "LedControl.h" //  need the library
LedControl lc=LedControl(12,11,10,2); // 

// pin 12 is connected to the MAX7219 pin 1
// pin 11 is connected to the CLK pin 13
// pin 10 is connected to LOAD pin 12
// 1 as we are only using 1 MAX7219

void setup()
{
  lc.shutdown(0,false);// turn off power saving, enables display
  lc.setIntensity(0,8);// sets brightness (0~15 possible values)
  lc.clearDisplay(0);// clear screen

  lc.shutdown(1,false);// turn off power saving, enables display
  lc.setIntensity(1,8);// sets brightness (0~15 possible values)
  lc.clearDisplay(1);// clear screen
}

void loop()
{
  for (int row=0; row<8; row++)
  {
    for (int col=0; col<8; col++)
    {
      lc.setLed(0,col,row,true); // turns on LED at col, row
      lc.setLed(1,col,row,false); // turns on LED at col, row
      delay(25);
    }
  }

  for (int row=0; row<8; row++)
  {
    for (int col=0; col<8; col++)
    {
      lc.setLed(0,col,row,false); // turns off LED at col, row
      lc.setLed(1,col,row,true); // turns on LED at col, row      
      delay(25);
    }
  }
}

And again, a quick demonstration:

Another fun use of the MAX7219 and LED matrices is to display scrolling text. For the case of simplicity we’ll use the LedControl library and the two LED matrix modules from the previous examples.

First our example sketch – it is quite long however most of this is due to defining the characters for each letter of the alphabet and so on. We’ll explain it at the other end!

// based on an orginal sketch by Arduino forum member "danigom"
// http://forum.arduino.cc/index.php?action=profile;u=188950

#include <avr/pgmspace.h>
#include <LedControl.h>

const int numDevices = 2;      // number of MAX7219s used
const long scrollDelay = 75;   // adjust scrolling speed

unsigned long bufferLong [14] = {0}; 

LedControl lc=LedControl(12,11,10,numDevices);

prog_uchar scrollText[] PROGMEM ={
    "  THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG 1234567890 the quick brown fox jumped over the lazy dog   \0"};

void setup(){
    for (int x=0; x<numDevices; x++){
        lc.shutdown(x,false);       //The MAX72XX is in power-saving mode on startup
        lc.setIntensity(x,8);       // Set the brightness to default value
        lc.clearDisplay(x);         // and clear the display
    }
}

void loop(){ 
    scrollMessage(scrollText);
    scrollFont();
}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////

prog_uchar font5x7 [] PROGMEM = {      //Numeric Font Matrix (Arranged as 7x font data + 1x kerning data)
    B00000000,	//Space (Char 0x20)
    B00000000,
    B00000000,
    B00000000,
    B00000000,
    B00000000,
    B00000000,
    6,

    B10000000,	//!
    B10000000,
    B10000000,
    B10000000,
    B00000000,
    B00000000,
    B10000000,
    2,

    B10100000,	//"
    B10100000,
    B10100000,
    B00000000,
    B00000000,
    B00000000,
    B00000000,
    4,

    B01010000,	//#
    B01010000,
    B11111000,
    B01010000,
    B11111000,
    B01010000,
    B01010000,
    6,

    B00100000,	//$
    B01111000,
    B10100000,
    B01110000,
    B00101000,
    B11110000,
    B00100000,
    6,

    B11000000,	//%
    B11001000,
    B00010000,
    B00100000,
    B01000000,
    B10011000,
    B00011000,
    6,

    B01100000,	//&
    B10010000,
    B10100000,
    B01000000,
    B10101000,
    B10010000,
    B01101000,
    6,

    B11000000,	//'
    B01000000,
    B10000000,
    B00000000,
    B00000000,
    B00000000,
    B00000000,
    3,

    B00100000,	//(
    B01000000,
    B10000000,
    B10000000,
    B10000000,
    B01000000,
    B00100000,
    4,

    B10000000,	//)
    B01000000,
    B00100000,
    B00100000,
    B00100000,
    B01000000,
    B10000000,
    4,

    B00000000,	//*
    B00100000,
    B10101000,
    B01110000,
    B10101000,
    B00100000,
    B00000000,
    6,

    B00000000,	//+
    B00100000,
    B00100000,
    B11111000,
    B00100000,
    B00100000,
    B00000000,
    6,

    B00000000,	//,
    B00000000,
    B00000000,
    B00000000,
    B11000000,
    B01000000,
    B10000000,
    3,

    B00000000,	//-
    B00000000,
    B11111000,
    B00000000,
    B00000000,
    B00000000,
    B00000000,
    6,

    B00000000,	//.
    B00000000,
    B00000000,
    B00000000,
    B00000000,
    B11000000,
    B11000000,
    3,

    B00000000,	///
    B00001000,
    B00010000,
    B00100000,
    B01000000,
    B10000000,
    B00000000,
    6,

    B01110000,	//0
    B10001000,
    B10011000,
    B10101000,
    B11001000,
    B10001000,
    B01110000,
    6,

    B01000000,	//1
    B11000000,
    B01000000,
    B01000000,
    B01000000,
    B01000000,
    B11100000,
    4,

    B01110000,	//2
    B10001000,
    B00001000,
    B00010000,
    B00100000,
    B01000000,
    B11111000,
    6,

    B11111000,	//3
    B00010000,
    B00100000,
    B00010000,
    B00001000,
    B10001000,
    B01110000,
    6,

    B00010000,	//4
    B00110000,
    B01010000,
    B10010000,
    B11111000,
    B00010000,
    B00010000,
    6,

    B11111000,	//5
    B10000000,
    B11110000,
    B00001000,
    B00001000,
    B10001000,
    B01110000,
    6,

    B00110000,	//6
    B01000000,
    B10000000,
    B11110000,
    B10001000,
    B10001000,
    B01110000,
    6,

    B11111000,	//7
    B10001000,
    B00001000,
    B00010000,
    B00100000,
    B00100000,
    B00100000,
    6,

    B01110000,	//8
    B10001000,
    B10001000,
    B01110000,
    B10001000,
    B10001000,
    B01110000,
    6,

    B01110000,	//9
    B10001000,
    B10001000,
    B01111000,
    B00001000,
    B00010000,
    B01100000,
    6,

    B00000000,	//:
    B11000000,
    B11000000,
    B00000000,
    B11000000,
    B11000000,
    B00000000,
    3,

    B00000000,	//;
    B11000000,
    B11000000,
    B00000000,
    B11000000,
    B01000000,
    B10000000,
    3,

    B00010000,	//<
    B00100000,
    B01000000,
    B10000000,
    B01000000,
    B00100000,
    B00010000,
    5,

    B00000000,	//=
    B00000000,
    B11111000,
    B00000000,
    B11111000,
    B00000000,
    B00000000,
    6,

    B10000000,	//>
    B01000000,
    B00100000,
    B00010000,
    B00100000,
    B01000000,
    B10000000,
    5,

    B01110000,	//?
    B10001000,
    B00001000,
    B00010000,
    B00100000,
    B00000000,
    B00100000,
    6,

    B01110000,	//@
    B10001000,
    B00001000,
    B01101000,
    B10101000,
    B10101000,
    B01110000,
    6,

    B01110000,	//A
    B10001000,
    B10001000,
    B10001000,
    B11111000,
    B10001000,
    B10001000,
    6,

    B11110000,	//B
    B10001000,
    B10001000,
    B11110000,
    B10001000,
    B10001000,
    B11110000,
    6,

    B01110000,	//C
    B10001000,
    B10000000,
    B10000000,
    B10000000,
    B10001000,
    B01110000,
    6,

    B11100000,	//D
    B10010000,
    B10001000,
    B10001000,
    B10001000,
    B10010000,
    B11100000,
    6,

    B11111000,	//E
    B10000000,
    B10000000,
    B11110000,
    B10000000,
    B10000000,
    B11111000,
    6,

    B11111000,	//F
    B10000000,
    B10000000,
    B11110000,
    B10000000,
    B10000000,
    B10000000,
    6,

    B01110000,	//G
    B10001000,
    B10000000,
    B10111000,
    B10001000,
    B10001000,
    B01111000,
    6,

    B10001000,	//H
    B10001000,
    B10001000,
    B11111000,
    B10001000,
    B10001000,
    B10001000,
    6,

    B11100000,	//I
    B01000000,
    B01000000,
    B01000000,
    B01000000,
    B01000000,
    B11100000,
    4,

    B00111000,	//J
    B00010000,
    B00010000,
    B00010000,
    B00010000,
    B10010000,
    B01100000,
    6,

    B10001000,	//K
    B10010000,
    B10100000,
    B11000000,
    B10100000,
    B10010000,
    B10001000,
    6,

    B10000000,	//L
    B10000000,
    B10000000,
    B10000000,
    B10000000,
    B10000000,
    B11111000,
    6,

    B10001000,	//M
    B11011000,
    B10101000,
    B10101000,
    B10001000,
    B10001000,
    B10001000,
    6,

    B10001000,	//N
    B10001000,
    B11001000,
    B10101000,
    B10011000,
    B10001000,
    B10001000,
    6,

    B01110000,	//O
    B10001000,
    B10001000,
    B10001000,
    B10001000,
    B10001000,
    B01110000,
    6,

    B11110000,	//P
    B10001000,
    B10001000,
    B11110000,
    B10000000,
    B10000000,
    B10000000,
    6,

    B01110000,	//Q
    B10001000,
    B10001000,
    B10001000,
    B10101000,
    B10010000,
    B01101000,
    6,

    B11110000,	//R
    B10001000,
    B10001000,
    B11110000,
    B10100000,
    B10010000,
    B10001000,
    6,

    B01111000,	//S
    B10000000,
    B10000000,
    B01110000,
    B00001000,
    B00001000,
    B11110000,
    6,

    B11111000,	//T
    B00100000,
    B00100000,
    B00100000,
    B00100000,
    B00100000,
    B00100000,
    6,

    B10001000,	//U
    B10001000,
    B10001000,
    B10001000,
    B10001000,
    B10001000,
    B01110000,
    6,

    B10001000,	//V
    B10001000,
    B10001000,
    B10001000,
    B10001000,
    B01010000,
    B00100000,
    6,

    B10001000,	//W
    B10001000,
    B10001000,
    B10101000,
    B10101000,
    B10101000,
    B01010000,
    6,

    B10001000,	//X
    B10001000,
    B01010000,
    B00100000,
    B01010000,
    B10001000,
    B10001000,
    6,

    B10001000,	//Y
    B10001000,
    B10001000,
    B01010000,
    B00100000,
    B00100000,
    B00100000,
    6,

    B11111000,	//Z
    B00001000,
    B00010000,
    B00100000,
    B01000000,
    B10000000,
    B11111000,
    6,

    B11100000,	//[
    B10000000,
    B10000000,
    B10000000,
    B10000000,
    B10000000,
    B11100000,
    4,

    B00000000,	//(Backward Slash)
    B10000000,
    B01000000,
    B00100000,
    B00010000,
    B00001000,
    B00000000,
    6,

    B11100000,	//]
    B00100000,
    B00100000,
    B00100000,
    B00100000,
    B00100000,
    B11100000,
    4,

    B00100000,	//^
    B01010000,
    B10001000,
    B00000000,
    B00000000,
    B00000000,
    B00000000,
    6,

    B00000000,	//_
    B00000000,
    B00000000,
    B00000000,
    B00000000,
    B00000000,
    B11111000,
    6,

    B10000000,	//`
    B01000000,
    B00100000,
    B00000000,
    B00000000,
    B00000000,
    B00000000,
    4,

    B00000000,	//a
    B00000000,
    B01110000,
    B00001000,
    B01111000,
    B10001000,
    B01111000,
    6,

    B10000000,	//b
    B10000000,
    B10110000,
    B11001000,
    B10001000,
    B10001000,
    B11110000,
    6,

    B00000000,	//c
    B00000000,
    B01110000,
    B10001000,
    B10000000,
    B10001000,
    B01110000,
    6,

    B00001000,	//d
    B00001000,
    B01101000,
    B10011000,
    B10001000,
    B10001000,
    B01111000,
    6,

    B00000000,	//e
    B00000000,
    B01110000,
    B10001000,
    B11111000,
    B10000000,
    B01110000,
    6,

    B00110000,	//f
    B01001000,
    B01000000,
    B11100000,
    B01000000,
    B01000000,
    B01000000,
    6,

    B00000000,	//g
    B01111000,
    B10001000,
    B10001000,
    B01111000,
    B00001000,
    B01110000,
    6,

    B10000000,	//h
    B10000000,
    B10110000,
    B11001000,
    B10001000,
    B10001000,
    B10001000,
    6,

    B01000000,	//i
    B00000000,
    B11000000,
    B01000000,
    B01000000,
    B01000000,
    B11100000,
    4,

    B00010000,	//j
    B00000000,
    B00110000,
    B00010000,
    B00010000,
    B10010000,
    B01100000,
    5,

    B10000000,	//k
    B10000000,
    B10010000,
    B10100000,
    B11000000,
    B10100000,
    B10010000,
    5,

    B11000000,	//l
    B01000000,
    B01000000,
    B01000000,
    B01000000,
    B01000000,
    B11100000,
    4,

    B00000000,	//m
    B00000000,
    B11010000,
    B10101000,
    B10101000,
    B10001000,
    B10001000,
    6,

    B00000000,	//n
    B00000000,
    B10110000,
    B11001000,
    B10001000,
    B10001000,
    B10001000,
    6,

    B00000000,	//o
    B00000000,
    B01110000,
    B10001000,
    B10001000,
    B10001000,
    B01110000,
    6,

    B00000000,	//p
    B00000000,
    B11110000,
    B10001000,
    B11110000,
    B10000000,
    B10000000,
    6,

    B00000000,	//q
    B00000000,
    B01101000,
    B10011000,
    B01111000,
    B00001000,
    B00001000,
    6,

    B00000000,	//r
    B00000000,
    B10110000,
    B11001000,
    B10000000,
    B10000000,
    B10000000,
    6,

    B00000000,	//s
    B00000000,
    B01110000,
    B10000000,
    B01110000,
    B00001000,
    B11110000,
    6,

    B01000000,	//t
    B01000000,
    B11100000,
    B01000000,
    B01000000,
    B01001000,
    B00110000,
    6,

    B00000000,	//u
    B00000000,
    B10001000,
    B10001000,
    B10001000,
    B10011000,
    B01101000,
    6,

    B00000000,	//v
    B00000000,
    B10001000,
    B10001000,
    B10001000,
    B01010000,
    B00100000,
    6,

    B00000000,	//w
    B00000000,
    B10001000,
    B10101000,
    B10101000,
    B10101000,
    B01010000,
    6,

    B00000000,	//x
    B00000000,
    B10001000,
    B01010000,
    B00100000,
    B01010000,
    B10001000,
    6,

    B00000000,	//y
    B00000000,
    B10001000,
    B10001000,
    B01111000,
    B00001000,
    B01110000,
    6,

    B00000000,	//z
    B00000000,
    B11111000,
    B00010000,
    B00100000,
    B01000000,
    B11111000,
    6,

    B00100000,	//{
    B01000000,
    B01000000,
    B10000000,
    B01000000,
    B01000000,
    B00100000,
    4,

    B10000000,	//|
    B10000000,
    B10000000,
    B10000000,
    B10000000,
    B10000000,
    B10000000,
    2,

    B10000000,	//}
    B01000000,
    B01000000,
    B00100000,
    B01000000,
    B01000000,
    B10000000,
    4,

    B00000000,	//~
    B00000000,
    B00000000,
    B01101000,
    B10010000,
    B00000000,
    B00000000,
    6,

    B01100000,	// (Char 0x7F)
    B10010000,
    B10010000,
    B01100000,
    B00000000,
    B00000000,
    B00000000,
    5
};

void scrollFont() {
    for (int counter=0x20;counter<0x80;counter++){
        loadBufferLong(counter);
        delay(500);
    }
}

// Scroll Message
void scrollMessage(prog_uchar * messageString) {
    int counter = 0;
    int myChar=0;
    do {
        // read back a char 
        myChar =  pgm_read_byte_near(messageString + counter); 
        if (myChar != 0){
            loadBufferLong(myChar);
        }
        counter++;
    } 
    while (myChar != 0);
}
// Load character into scroll buffer
void loadBufferLong(int ascii){
    if (ascii >= 0x20 && ascii <=0x7f){
        for (int a=0;a<7;a++){                      // Loop 7 times for a 5x7 font
            unsigned long c = pgm_read_byte_near(font5x7 + ((ascii - 0x20) * 8) + a);     // Index into character table to get row data
            unsigned long x = bufferLong [a*2];     // Load current scroll buffer
            x = x | c;                              // OR the new character onto end of current
            bufferLong [a*2] = x;                   // Store in buffer
        }
        byte count = pgm_read_byte_near(font5x7 +((ascii - 0x20) * 8) + 7);     // Index into character table for kerning data
        for (byte x=0; x<count;x++){
            rotateBufferLong();
            printBufferLong();
            delay(scrollDelay);
        }
    }
}
// Rotate the buffer
void rotateBufferLong(){
    for (int a=0;a<7;a++){                      // Loop 7 times for a 5x7 font
        unsigned long x = bufferLong [a*2];     // Get low buffer entry
        byte b = bitRead(x,31);                 // Copy high order bit that gets lost in rotation
        x = x<<1;                               // Rotate left one bit
        bufferLong [a*2] = x;                   // Store new low buffer
        x = bufferLong [a*2+1];                 // Get high buffer entry
        x = x<<1;                               // Rotate left one bit
        bitWrite(x,0,b);                        // Store saved bit
        bufferLong [a*2+1] = x;                 // Store new high buffer
    }
}  
// Display Buffer on LED matrix
void printBufferLong(){
  for (int a=0;a<7;a++){                    // Loop 7 times for a 5x7 font
    unsigned long x = bufferLong [a*2+1];   // Get high buffer entry
    byte y = x;                             // Mask off first character
    lc.setRow(3,a,y);                       // Send row to relevent MAX7219 chip
    x = bufferLong [a*2];                   // Get low buffer entry
    y = (x>>24);                            // Mask off second character
    lc.setRow(2,a,y);                       // Send row to relevent MAX7219 chip
    y = (x>>16);                            // Mask off third character
    lc.setRow(1,a,y);                       // Send row to relevent MAX7219 chip
    y = (x>>8);                             // Mask off forth character
    lc.setRow(0,a,y);                       // Send row to relevent MAX7219 chip
  }
}

The pertinent parts are at the top of the sketch – the following line sets the number of MAX7219s in the hardware:

const int numDevices = 2;

The following can be adjusted to change the speed of text scrolling:

const long scrollDelay = 75;

… then place the text to scroll in the following (for example):

prog_uchar scrollText[] PROGMEM ={
    "  THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG 1234567890 the quick brown fox jumped over the lazy dog   \0"};

Finally – to scroll the text on demand, use the following:

scrollMessage(scrollText);

You can then incorporate the code into your own sketches. And a video of the example sketch in action:

Although we used the LedControl library, there are many others out there for scrolling text. One interesting example is Parola  – which is incredibly customisable. If you’re looking for a much larger device to scroll text, check out the Freetronics DMD range.

Controlling LED numeric displays with the MAX7219

Using the MAX7219 and the LedControl library you can also drive numeric LED displays – up to eight digits from the one MAX7219. This gives you the ability to make various numeric displays that are clear to read and easy to control. When shopping around for numeric LED displays, make sure you have the common-cathode type.

Connecting numeric displays is quite simple, consider the following schematic which should appear familiar by now:

The schematic shows the connections for modules or groups of up to eight digits. Each digit’s A~F and dp (decimal point) anodes connect together to the MAX7219, and each digit’s cathode connects in order as well. The MAX7219 will display each digit in turn by using one cathode at a time. Of course if you want more than eight digits, connect another MAX7219 just as we did with the LED matrices previously.

The required code in the sketch is identical to the LED matrix code, however to display individual digits we use:

lc.setDigit(A, B, C, D);

where A is the MAX7219 we’re using, B is the digit to use (from a possible 0 to 7), C is the digit to display (0~9… if you use 10~15 it will display A~F respectively) and D is false/true (digit on or off). You can also send basic characters such as a dash “-” with the following:

lc.setChar(A, B,'-',false);

Now let’s put together an example of eight digits:

#include "LedControl.h" //  need the library
LedControl lc=LedControl(12,11,10,1); // lc is our object
// pin 12 is connected to the MAX7219 pin 1
// pin 11 is connected to the CLK pin 13
// pin 10 is connected to LOAD pin 12
// 1 as we are only using 1 MAX7219
void setup()
{
  // the zero refers to the MAX7219 number, it is zero for 1 chip
  lc.shutdown(0,false);// turn off power saving, enables display
  lc.setIntensity(0,8);// sets brightness (0~15 possible values)
  lc.clearDisplay(0);// clear screen
}
void loop()
{
  for (int a=0; a<8; a++)
  {
    lc.setDigit(0,a,a,true);
    delay(100);
  }
  for (int a=0; a<8; a++)
  {
    lc.setDigit(0,a,8,1);
    delay(100);
  }
  for (int a=0; a<8; a++)
  {
    lc.setDigit(0,a,0,false);
    delay(100);
  }
  for (int a=0; a<8; a++)
  {
    lc.setChar(0,a,' ',false);
    delay(100);
  }
  for (int a=0; a<8; a++)
  {
    lc.setChar(0,a,'-',false);
    delay(100);
  }
  for (int a=0; a<8; a++)
  {
    lc.setChar(0,a,' ',false);
    delay(100);
  }
}

and the sketch in action:

Conclusion

By now you’re on your way to controlling an incredibly useful part with your Arduino. Don’t forget – there are many variations of Arduino libraries for the MAX7219, we can’t cover each one – so have fun and experiment with them. And if you enjoyed the tutorial, or want to introduce someone else to the interesting world of Arduino – check out my book (now in a third printing!) “Arduino Workshop” from No Starch Press.

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitter, Google+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

The post Tutorial – Arduino and the MAX7219 LED Display Driver IC appeared first on tronixstuff.

Peripheral Vision 007: Tyler DeAngelo - 'wasting time is an important piece of innovation'

"There's something we miss when everything becomes virtual and goes online," says Tyler DeAngelo. "Tactile-ness gives it something that is more interesting and a deeper connection and makes it more meaningful." The ad executive invited us to Havas Worldwide's Chicago offices to show off his latest creation, and with Fifth Avenue Frogger, the Check 'N Chew Foursquare gumball machine and the Buzzed Buzzer under his belt, we took him up on the offer. His latest creation was born of the same desire to bridge the physical and the virtual. Created for a beer client, the bottle opener has Arduino Nano-based circuitry built-in, which connects with an Android handset via Bluetooth, sending texts to friends when you crack open a bottle.

"I'm definitely not the first person to say this, but creativity comes from finding meaningful relationships between things that already exist," explains DeAngelo. "Nothing I'm doing is going to change the world. A lot of the stuff I do is wasting people's time, but I still think that making someone think differently or making someone laugh or have fun -- wasting time is an important piece of innovation." It's also, naturally, an important part of engaging a public increasingly immune to sales pitches. Getting people's attention in an ad-saturated world requires a lot more than clever jingles. "i think the most innovative things in the media field should be happening inside ad agencies right now," DeAngelo adds. "If they're not, those who aren't innovating are going to be dead."

Filed under: Peripherals

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Intel launches Galileo, an Arduino-compatible development board

Notice how so many maker projects require open-source hardware like Arduino and Raspberry Pi to function? Intel has, and the company is leaping into bed with the former to produce the Galileo development board. Galileo is the first product packing Intel's Quark X1000 system-on-chip, Santa Clara's (designed in Ireland, trivia fans) new low-power gear for wearables and "internet of things" devices. Don't imagine, however, that Intel is abandoning its X86 roots, as Quark's beating heart is a single-thread Pentium-based 400MHz CPU. As part of the new project, Intel will be handing out 50,000 of the boards to 1,000 universities over the next 18 months -- a move which we're sure will make Eben Upton and Co. delighted and nervous at the same time.

Filed under: Misc, Wireless, Intel

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Engadget 03 Oct 12:18

Review – Freetronics 128×128 Pixel Colour OLED Module

Introduction

Time for another review, and in this instalment we have the new 128×128 Pixel OLED Module from Freetronics. It’s been a while since we’ve had a full-colour graphic display to experiment with, and this one doesn’t disappoint. Unlike other displays such as LCD, this one uses OLED – “Organic Light-Emitting Diode” technology.

OLEDs allow for a faster refresh rate, and to the naked eye has a great amount of colour contrast. Furthermore the viewing angles are excellent, you can clearly read the display from almost any angle, for example:

However they can suffer from burn-in from extended display of the same thing so that does need to be taken into account. Nevertheless they provide an inexpensive and easy-to-use method of displaying colour text, graphics and even video from a variety of development boards. Finally – there is also a microSD socket for data logging, image storage or other uses. However back to the review unit. It arrives in typical retail packaging:

and includes the OLED display itself, a nifty reusable parts tray/storage box, and two buttons. The display has a resolution of 128 x 128 pixels and has a square display area with a diagonal size of 38.1 mm. The unit itself is quite compact:

The display is easily mounted using the holes on the left and right-hand side of the display. The designers have also allowed space for an LED, current-limiting resistor and button on each side, for user input or gaming – perfect for the  included buttons. However this section of the PCB is also scored-off so you can remove them if required. Using the OLED isn’t difficult, and tutorials have been provided for both Arduino and Raspberry Pi users.

Using with Arduino

After installing the Arduino library, it’s a simple matter of running some jumper wires from the Arduino or compatible board to the display – explained in detail with the “Quickstart” guide. Normally I would would explain how to use the display myself, however in this instance a full guide has been published which explains how to display text of various colours, graphics, displaying images stored on a microSD card and more. Finally there’s some interesting demonstration sketches included with the library. For example, displaying large amounts of text:

… the variety of fonts available:

… and for those interested in monitoring changing data types, a very neat ECG-style of sketch:

… and the mandatory rotating cube from a Freetronics forum member:

Using with Raspberry Pi

For users of this popular single-board computer, there’s a great tutorial and some example videos available on the Freetronics website for your consideration, such as the following video clip playback:

Support

Along with the Arduino and Raspberry Pi tutorials, there’s also the Freetronics support forum where members have been experimenting with accelerated drivers, demonstrations and more.

Competition!

For a chance to win your own OLED display, send a postcard with your email address clearly printed on the back to:

OLED Competition, PO Box 5435 Clayton 3168 Australia. 

Cards must be received by 24/10/2013. One card will then be selected at random and the winner will be sent one Freetronics OLED Display. Prize will be delivered by Australia Post standard air mail. We’re not responsible for customs or import duties, VAT, GST, import duty, postage delays, non-delivery or whatever walls your country puts up against receiving inbound mail.

Conclusion

Compared to previous colour LCD units used in the past, OLED technology is a great improvement – and demonstrated very well with this unit. Furthermore you get the whole package – anyone call sell you a display, however Freetronics also have the support, tutorials, drivers and backup missing from other retailers. So if you need a colour display, check it out.

And for more detail, full-sized images from this article can be found on flickr. And if you’re interested in learning more about Arduino, or want to introduce someone else to the interesting world of Arduino – check out my book (now in a third printing!) “Arduino Workshop” from No Starch Press.

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitter, Google+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

[Note – OLED display was a promotional consideration from Freetronics]

The post Review – Freetronics 128×128 Pixel Colour OLED Module appeared first on tronixstuff.

First look – Arduino Yún

Introduction

After being announced in May this year, the new Arduino Yún has arrived in the crowded marketplace – and I snapped up one of the first to arrive in Australia for an initial review. The purpose of which is to run through the out of box experience, and to see how easy it was to get the Yún working with the promised new features.

[Update – over time we’ll publish tutorials specifically for the Yún, which are listed here.]

The Yún introduces some interesting new combinations of hardware and connectivity, all within the familiar form-factor. Which gives us plenty to examine and write about, so let’s get started. First, a quick look around the Yún:

Notice the stickers on the header sockets, useful for beginners or the absent-minded…

The usual TX/RX and D13 LEDs, plus notifiers for power, WiFi, LAN and USB use…

Ethernet, USB programming, USB host…

Again with the stickers…

The rear is quite busy. You can also see “Made in Taiwan” – a first for Arduino. I believe the reason for this was due to the new Atheros chipset requirements. Did you notice the multiple reset buttons? There are three – one for the Arduino, one for wifi and one to reboot Linino. As you can see there’s a lot of circuity on the bottom of the Yún, so it would be prudent to use some short standoffs to elevate the board and protect the bottom. Before moving on, you might like the following video where the Arduino team introduce the Yún:

Specifications

The Yún is based around the Arduino Leonardo-specification board – thus you have the ATmega32U4 microcontroller and the usual Leonardo functions. Note you cannot feed wild DC voltages into the Vin pin – it must be a regulated 5V. And the DC socket has gone, so for a solid connection you might want to make or buy your own power shield.

However there is so much more… underneath a small metal shield below the digital I/O pins is an Atheros AR9331 CPU running a Linux distribution based on OpenWRT named Linino. This Atheros part of the board is connected to a microSD socket, 10/100 Ethernet port, a USB 2.0 socket for host-mode functions and also has IEEE 802.11b/g/n WiFi, and Power-over-Ethernet support (with an optional adaptor).

And all of that is connected to the Arduino side of things via a simple serial “bridge” connection (with it’s own library) – which gives the Arduino side of the board very simple methods of controlling the other onboard hardware.

Getting started with the Yún WiFi

First thing is to download and install the new IDE, version 1.5.4. This is for Due and Yún, so keep your older installations as well. On the general Arduino side of things nothing has changed, so we’ll move on to the more interesting side of the board. The first of these is to setup and experiment with the onboard WiFi. After connecting your board to USB for power, you can connect to it with your PC’s WiFi:

… at which point you connect to the Yún network. Then visit 192.168.240.1 from a web browser, and you’re presented with a page that asks for the default password, which is … “arduino”:

At which point you’re presented with the relevant details for your Yún:

… such as the IP address, MAC address, etc. Make note of your MAC address, you might need it later. From here you can configure the Yún WiFi details, for example the name and password, and also the details of your existing WiFi network which can be used to access the Yún. Once you save those, the Yún reboots and tells you to connect the PC back to the existing WiFi network:

If for some reason it doesn’t work or you entered the wrong settings – hold down the “WLAN RST” button (next to the USB host socket) for five seconds. This sets the WiFi details in the Yun back to the default … and you can start all over again.

Note that the Yún’s preset IP of 192.168.240.1 may not be suitable for your own network. For example, if your home router is 10.1.1.1 you need to do some detective work to find out the IP address for the Yún. Head into your router’s administration pages and look for your DHCP Client Log. It will show a list of devices that are connected to the network, including their MAC and IP address – for example:

Then it’s a simple matter of finding the MAC address in the list and the matching IP. Once you have the IP address, enter that into a web browser and after being prompted for the Yún’s password, you’re back to the welcome page with the IP, MAC addresses etc.

WiFi Sketch Uploading

Once your Yún is on the same WiFi network as the PC running the IDE – you can upload a sketch over WiFi! This is possible due to the bridge between the Atheros section on the board and the Arduino hardware. Just select the board type as normal in the IDE, and the port (the IP address version):

… then hit Upload as normal, enter the password:

and you’re done. Awesome.

Console-based control of Arduino over WiFi

There’s a neat example that demonstrates how you can control the Arduino over the WiFi using a console terminal on the PC. Upload this sketch (from http://arduino.cc/en/Guide/ArduinoYun#toc13):

#include <Console.h>

const int ledPin = 13; // the pin that the LED is attached to
int incomingByte;      // a variable to read incoming serial data into

void setup() {
  // initialize serial communication:
  Bridge.begin();
  Console.begin(); 

  while (!Console){
    ; // wait for Console port to connect.
  }
  Console.println("You're connected to the Console!!!!");
  // initialize the LED pin as an output:
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // see if there's incoming serial data:
  if (Console.available() > 0) {
    // read the oldest byte in the serial buffer:
    incomingByte = Console.read();
    // if it's a capital H (ASCII 72), turn on the LED:
    if (incomingByte == 'H') {
      digitalWrite(ledPin, HIGH);
    } 
    // if it's an L (ASCII 76) turn off the LED:
    if (incomingByte == 'L') {
      digitalWrite(ledPin, LOW);
    }
  }
}

Then load your terminal software. We use PuTTY on Windows. Run the terminal software, then login as root, then telnet to “localhost 6571”:

You can then send characters to the Yún just as you would with a USB-connected Arduino via the serial monitor. With the example above you’re turning the D13 LED on and off, but you can get the idea.

The “Internet of Things”

Arduino has teamed up with a service called “Temboo” – which gives you over 100 APIs that your Yún can hook up with to do a myriad of things, such as send tweets, get weather data from Yahoo, interact with Dropbox, etc. This is done easily and explained quite well at the Temboo website. After signing up for Temboo (one account seems to be free at the moment) we tried the Yahoo weather API.

You enter the parameters using an online form in Temboo (in our example, the address of the area whose weather forecast we required), and the Temboo site gives you the required Arduno sketch and header file to upload. And you’re done. With this particular example, I wanted the weather in Sydney CBD – and once running the data is returned to the serial monitor, for example:

It was great to see that work the very first time, and a credit to Temboo and Arduino for making it happen. But how?

There is a Temboo client in the Linino OS, which is the gateway to the API via WiFi, and also communicates with the Arduino via the serial bridge. The Arduino Temboo library can then interact with the Linino client without complex code. The weather data is then returned back from the Internet via the Temboo client and fed to the Arduino serial port, where you can parse it with your own code. This looks like a lot of fun, and also could be quite useful – for example capturing data and sending it to a Google Docs spreadsheet. For more information, check out the Temboo website.

However you can delve deeper and create your own APIs, matching code – and perhaps other services will develop their own APIs in the near future. But for now, it’s a good start.

Where to from here? And support?

This article has only scratched the surface (but not bad considering the board arrived a few hours ago). There’s plenty more examples on the getting started page, in the IDE (under “Bridge”) – plus a dedicated Arduino Yún forum. And check out this gmail notifier. In the near future we’ll create some of our own tutorials, so stay tuned.

Is the Yún a completely open-source product? 

Well it says “open source electronics prototyping platform” on the rear, but is this true? The Arduino Leonardo-side of the board is. However the Atheros AR9331 chip is not. Nevertheless, are you really going to reproduce your own AR9331? So it doesn’t really matter. Being a pragmatist I propose that the Yún solves the problem of Arduino and Internet connectivity quite well for the non-advanced user – so not being totally OSHW isn’t an issue.

Support

This board is very new to us here, so for questions or support please ask on the dedicated Arduino Yún forum.

Conclusion

Since the popularity of various single-board computers has increased exponentially over the last few months, some may say that the Yún is perhaps too little, too late. After only having the Yún for a few hours before writing this article, personally I disagree with this statement – the Yún is a device that still gives us the wide range of hardware control, and what looks to be a very simple method of connectivity that surely is cheaper and less prone to issues than the original Arduino WiFi shield.

What the Yún gives us is a simple, well-executed method of getting our Arduino connected to the outside world – and in a manner that won’t confuse or put off the beginner or intermediate user. So for now, it’s a win.

What do you think? Leave a comment below.

And for more detail, full-sized images from this article can be found on flickr. And if you’re interested in learning more about Arduino, or want to introduce someone else to the interesting world of Arduino – check out my book (now in a third printing!) “Arduino Workshop” from No Starch Press.

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitter, Google+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

The post First look – Arduino Yún appeared first on tronixstuff.

Tronixstuff 18 Sep 14:39