Introduction

In the same manner as their MSP430 development board, Texas Instruments also have another LaunchPad board with their powerful Stellaris LM4F120H5QR microcontroller. It’s an incredibly powerful and well-featured MCU – which offers an 80 MHz, 32-bit ARM Cortex-M4 CPU with floating point, 256 Kbytes of 100,000 write-erase cycle FLASH and many peripherals such as 1MSPS ADCs, eight UARTs, four SPIs, four I2Cs, USB & up to 27 timers, some configurable up to 64-bits.

That’s a bucket of power, memory and I/O for not much money – you can get the LaunchPad board for around $15. This LaunchPad has the in-circuit debugger, two user buttons, an RGB LED and connectors for I/O and shield-like booster packs:

and the other side:

However the good news as far as we’re concerned is that you can now use it with the Energia Arduino-compatible IDE that we examined previously. Before rushing out to order your own Stellaris board, install Energia and examine the available functions and libraries to make sure you can run what you need. And if so, you’re set for some cheap Arduino power.

Installation

Installation is simple, just get your download from here. If you’re running Windows 7 – get the USB drivers from here. When you plug your LaunchPad into the USB for the first time, wait until after Windows attempts to install the drivers, then install drivers manually after download via Device manager … three times (JTAG, virtual serial port and DFU device). Use the debug USB socket (and set the switch to debug) when installing and uploading code. If you get the following warning from Windows, just click “Install this driver software anyway”:

Once the drivers are installed, plug in your LaunchPad, wait a moment – then run Energia. You can then select your board type and serial port just like the Arduino IDE. Then go ahead and upload the “blink” example…

Awesome – check out all that free memory space. In the same manner as the MSP430, there are some hardware<>sketch differences you need to be aware of. For example, how to refer to the I/O pins in Energia? A map has been provided for front:

… and back:

As you can imagine, the Stellaris MCUs are different to an AVR, so a lot of hardware-specific code doesn’t port over from the world of Arduino. One of the first things to remember is that the Stellaris is a 3.3V device. Code may or may not be interchangeable, so a little research will be needed to match up the I/O pins and rewrite the sketch accordingly. For example, instead of digital pins numbers, you use PX_Y – see the map above. So let’s say you want to run through the RGB LED… consider the following sketch:

int wait = 500;
void setup() 
{ 
 // initialize the digital pin as an output.
 pinMode(PF_1, OUTPUT); // red 
 pinMode(PF_3, OUTPUT); // green
 pinMode(PF_2, OUTPUT); // blue
}
void loop() 
{
 digitalWrite(PF_1, HIGH); 
 delay(wait); 
 digitalWrite(PF_1, LOW); 
 digitalWrite(PF_3, HIGH); 
 delay(wait); 
 digitalWrite(PF_3, LOW); 
 digitalWrite(PF_2, HIGH); 
 delay(wait); 
 digitalWrite(PF_2, LOW); 
}

Which simply blinks the red, green and blue LED elements in series. Using digital inputs is in the same vein, and again the buttons are wired so when pressed they go LOW. An example of this in the following sketch:

void setup() 
{ 
 // initialize the digital pins
 pinMode(PF_1, OUTPUT); // red 
 pinMode(PF_3, OUTPUT); // green
 pinMode(PF_2, OUTPUT); // blue

 pinMode(PF_4, INPUT_PULLUP); // left - note _PULLUP
 pinMode(PF_0, INPUT_PULLUP); // right - note _PULLUP 
}
void blinkfast() 
{
 for (int i=0; i<10; i++)
 {
 digitalWrite(PF_1, HIGH); 
 delay(250); 
 digitalWrite(PF_1, LOW); 
 digitalWrite(PF_3, HIGH); 
 delay(250); 
 digitalWrite(PF_3, LOW); 
 digitalWrite(PF_2, HIGH); 
 delay(250); 
 digitalWrite(PF_2, LOW); 
 }
}
void blinkslow() 
{
 for (int i=0; i<5; i++)
 {
 digitalWrite(PF_1, HIGH); 
 delay(1000); 
 digitalWrite(PF_1, LOW); 
 digitalWrite(PF_3, HIGH); 
 delay(1000); 
 digitalWrite(PF_3, LOW); 
 digitalWrite(PF_2, HIGH); 
 delay(1000); 
 digitalWrite(PF_2, LOW); 
 }
}
void loop()
{
 if (digitalRead(PF_4)==LOW) { blinkslow(); }
 if (digitalRead(PF_0)==LOW) { blinkfast(); }
}

And for the non-believers:

Where to from here? 

Sometimes you can be platform agnostic, and just pick something that does what you want with the minimum of time and budget. Or to put it another way, if you need a fast CPU and plenty of space but couldn’t be bothered don’t have time to work with Keil, Code Composer Studio, IAR etc – the Energia/Stellaris combination could solve your problem. There’s a growing Energia/Stellaris forum, and libraries can be found here. At the time of writing we found an I2C library as well.

However to take full advantage of the board, consider going back to the TI tools and move forward with them. You can go further with the tutorials and CCS etc from Texas Instruments own pages.

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 Exploring the TI Stellaris platform with Energia Arduino-compatible IDE appeared first on tronixstuff.

Read the full article on MAKE

This is a tutorial on using the MSGEQ7 Spectrum Analyser with Arduino, and chapter forty-eight of a series originally titled “Getting Started/Moving Forward with Arduino!” by John Boxall – A tutorial on the Arduino universe. The first chapter is here, the complete series is detailed here.

Updated 10/11/2014

In this article we’re going to explain how to make simple spectrum analysers with an Arduino-style board. (Analyser? Analyzer? Take your pick).

First of all, what is a spectrum analyser? Good question. Do you remember what  this is?

It’s a mixed graphic equaliser/spectrum analyser deck for a hi-fi system. The display in the middle is the spectrum analyser, and roughly-speaking it shows the strength of  different frequencies in the music being listened to – and looked pretty awesome doing it. We can recreate displays similar to this for entertainment and also as a base for creative lighting effects. By working through this tutorial you’ll have the base knowledge to recreate these yourself.

We’ll be using the MSGEQ7 “seven band graphic equaliser IC” from Mixed Signal Integration. Here’s the MSGEQ7 data sheet (.pdf).  This little IC can accept a single audio source, analyse seven frequency bands of the audio, and output a DC representation of each frequency band. This isn’t super-accurate or calibrated in any way, but it works. You can get the IC separately, for example:

and then build your own circuit around it… or like most things in the Arduino world – get a shield. In this case, a derivative of the original Bliptronics shield by Sparkfun. It’s designed to pass through stereo audio via 3.5mm audio sockets and contains two MSGEQ7s, so we can do a stereo analyser:

As usual Sparkfun have saved a few cents by not including the stackable header sockets, so you’ll need to buy and solder those in yourself. There is also space for three header pins for direct audio input (left, right and common), which are useful – so if you can add those as well.

So now you have a shield that’s ready for use. Before moving forward let’s examine how the MSGEQ7 works for us. As mentioned earlier, it analyses seven frequency bands. These are illustrated in the following graph from the data sheet:

It will return the strengths of the audio at seven points – 63 Hz, 160 Hz, 400 Hz, 1 kHz, 2.5 kHz, 6.25 kHz and 16 kHz – and as you can see there is some overlap between the bands. The strength is returned as a DC voltage – which we can then simply measure with the Arduino’s analogue input and create a display of some sort. At this point audio purists, Sheldonites and RF people might get a little cranky, so once again – this is more for visual indication than any sort of calibration device.

However as an 8-pin IC a different approach is required to get the different levels. The IC will sequentially give out the levels for each band on pin 3- e.g. 63 Hz then 160 Hz then 400 Hz then 1 kHz then 2.5 kHz then 6.25 kHz  then 16 kHz then back to 63 Hz and so on. To start this sequence we first reset the IC by pulsing the RESET pin HIGH then low. This tells the IC to start at the first band. Next, we set the STROBE pin to LOW, take the DC reading from pin 3 with analogue input, store the value in a variable (an array), then set the STROBE pin HIGH. We repeat the strobe-measure sequence six more times to get the rest of the data, then RESET the IC and start all over again. For the visual learners consider the diagram below from the data sheet:

To demonstrate this process, consider the function

readMSGEQ7()

in the following example sketch:

// Example 48.1 - tronixstuff.com/tutorials > chapter 48 - 30 Jan 2013 
// MSGEQ7 spectrum analyser shield - basic demonstration
int strobe = 4; // strobe pins on digital 4
int res = 5; // reset pins on digital 5
int left[7]; // store band values in these arrays
int right[7];
int band;
void setup()
{
 Serial.begin(115200);
 pinMode(res, OUTPUT); // reset
 pinMode(strobe, OUTPUT); // strobe
 digitalWrite(res,LOW); // reset low
 digitalWrite(strobe,HIGH); //pin 5 is RESET on the shield
}
void readMSGEQ7()
// Function to read 7 band equalizers
{
 digitalWrite(res, HIGH);
 digitalWrite(res, LOW);
 for(band=0; band <7; band++)
 {
 digitalWrite(strobe,LOW); // strobe pin on the shield - kicks the IC up to the next band 
 delayMicroseconds(30); // 
 left[band] = analogRead(0); // store left band reading
 right[band] = analogRead(1); // ... and the right
 digitalWrite(strobe,HIGH); 
 }
}
void loop()
{
 readMSGEQ7();
 // display values of left channel on serial monitor
 for (band = 0; band < 7; band++)
 {
 Serial.print(left[band]);
 Serial.print(" ");
 }
 Serial.println();
// display values of right channel on serial monitor
 for (band = 0; band < 7; band++)
 {
 Serial.print(right[band]);
 Serial.print(" ");
 }
 Serial.println();
}

If you follow through the sketch, you can see that it reads both left- and right-channel values from the two MSGEQ7s on the shield, then stores each value in the arrays left[] and right[]. These values are then sent to the serial monitor for display – for example:

If you have a function generator, connect the output to one of the channels and GND – then adjust the frequency and amplitude to see how the values change. The following video clip is a short demonstration of this – we set the generator to 1 kHz and adjust the amplitude of the signal. To make things easier to read we only measure and display the left channel:

Keep an eye on the fourth column of data – this is the analogRead() value returned by the Arduino when reading the 1khz frequency band. You can also see the affect on the other bands around 1 kHz as we increase and decrease the frequency. However that wasn’t really visually appealing – so now we’ll create a small and large graphical version.

First we’ll use an inexpensive LCD, the I2C model from akafugu reviewed previously. To save repeating myself, also review how to create custom LCD characters from here.

With the LCD with have two rows of sixteen characters. The plan is to use the top row for the levels, the left-channel’s on … the left, and the right on the right. Each character will be a little bar graph for the level. The bottom row can be for a label. We don’t have too many pixels to work with, but it’s a compact example:

We have eight rows for each character, and the results from an analogueRead() fall between 0 and 1023. So that’s 1024 possible values spread over eight sections. Thus each row of pixels in each character will represent 128 “units of analogue read” or around 0.63 V if the Arduino is running from true 5 V (remember your AREF notes?). The sketch will again read the values from the MSGEQ7, feed them into two arrays – then display the required character in each band space  on the LCD.

Here’s the resulting sketch:

// Example 48.2 - tronixstuff.com/tutorials > chapter 48 - 30 Jan 2013 
// MSGEQ7 spectrum analyser shield and I2C LCD from akafugu
// for akafugu I2C LCD
#include "Wire.h"
#include "TWILiquidCrystal.h"
LiquidCrystal lcd(50);
// create custom characters for LCD
byte level0[8] = { 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b11111};
byte level1[8] = { 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b11111, 0b11111};
byte level2[8] = { 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b11111, 0b11111, 0b11111};
byte level3[8] = { 0b00000, 0b00000, 0b00000, 0b00000, 0b11111, 0b11111, 0b11111, 0b11111};
byte level4[8] = { 0b00000, 0b00000, 0b00000, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111};
byte level5[8] = { 0b00000, 0b00000, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111};
byte level6[8] = { 0b00000, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111};
byte level7[8] = { 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111};
int strobe = 4; // strobe pins on digital 4
int res = 5; // reset pins on digital 5
int left[7]; // store band values in these arrays
int right[7];
int band;
void setup()
{
 Serial.begin(9600);
 // setup LCD and custom characters
 lcd.begin(16, 2);
 lcd.setContrast(24);
 lcd.clear();
lcd.createChar(0,level0);
 lcd.createChar(1,level1);
 lcd.createChar(2,level2);
 lcd.createChar(3,level3);
 lcd.createChar(4,level4);
 lcd.createChar(5,level5);
 lcd.createChar(6,level6);
 lcd.createChar(7,level7);
 lcd.setCursor(0,1);
 lcd.print("Left");
 lcd.setCursor(11,1);
 lcd.print("Right");
 pinMode(res, OUTPUT); // reset
 pinMode(strobe, OUTPUT); // strobe
 digitalWrite(res,LOW); // reset low
 digitalWrite(strobe,HIGH); //pin 5 is RESET on the shield
}
void readMSGEQ7()
// Function to read 7 band equalizers
{
 digitalWrite(res, HIGH);
 digitalWrite(res, LOW);
 for( band = 0; band < 7; band++ )
 {
 digitalWrite(strobe,LOW); // strobe pin on the shield - kicks the IC up to the next band 
 delayMicroseconds(30); // 
 left[band] = analogRead(0); // store left band reading
 right[band] = analogRead(1); // ... and the right
 digitalWrite(strobe,HIGH); 
 }
}
void loop()
{
 readMSGEQ7();
// display values of left channel on LCD
 for( band = 0; band < 7; band++ )
 {
 lcd.setCursor(band,0);
 if (left[band]>=895) { lcd.write(7); } else
 if (left[band]>=767) { lcd.write(6); } else
 if (left[band]>=639) { lcd.write(5); } else
 if (left[band]>=511) { lcd.write(4); } else
 if (left[band]>=383) { lcd.write(3); } else
 if (left[band]>=255) { lcd.write(2); } else
 if (left[band]>=127) { lcd.write(1); } else
 if (left[band]>=0) { lcd.write(0); }
 }
 // display values of right channel on LCD
 for( band = 0; band < 7; band++ )
 {
 lcd.setCursor(band+9,0);
 if (right[band]>=895) { lcd.write(7); } else
 if (right[band]>=767) { lcd.write(6); } else
 if (right[band]>=639) { lcd.write(5); } else
 if (right[band]>=511) { lcd.write(4); } else
 if (right[band]>=383) { lcd.write(3); } else
 if (right[band]>=255) { lcd.write(2); } else
 if (right[band]>=127) { lcd.write(1); } else
 if (right[band]>=0) { lcd.write(0); }
 }
}

If you’ve been reading through my tutorials there isn’t anything new to worry about. And now for the demo, with sound –

That would look great on the side of a Walkman, however it’s a bit small. Let’s scale it up by using a Freetronics Dot Matrix Display – you may recall these from Clock One. For some background knowledge check the review here.  Don’t forget to use a suitable power supply for the DMD – 5 V at 4 A will do nicely. The DMD contains 16 rows of 32 LEDs. This gives us twice the “resolution” to display each band level if desired. The display style is subjective, so for this example we’ll use a single column of LEDs for each frequency band, with a blank column between each one.

We use a lot of line-drawing statements to display the levels, and clear the DMD after each display. With this and the previous sketches, there could be room for efficiency – however I write these with the beginner in mind. Here’s the sketch:

// Example 48.3 - tronixstuff.com/tutorials > chapter 48 - 30 Jan 2013 
// MSGEQ7 spectrum analyser shield with a Freetronics DMD
// for DMD
#include "DMD.h" // for DMD
#include "SPI.h" // SPI.h must be included as DMD is written by SPI (the IDE complains otherwise)
#include "TimerOne.h"
#include "SystemFont5x7.h" // keep next two lines if you want to add some text
#include "Arial_black_16.h"
DMD dmd(1, 1); // creates instance of DMD to refer to in sketch
void ScanDMD() // necessary interrupt handler for refresh scanning of DMD
{ 
 dmd.scanDisplayBySPI();
}
int strobe = 4; // strobe pins on digital 4
int res = 5; // reset pins on digital 5
int left[7]; // store band values in these arrays
int right[7];
int band;
void setup()
{
 // for DMD
 //initialize TimerOne's interrupt/CPU usage used to scan and refresh the display
 Timer1.initialize( 5000 ); //period in microseconds to call ScanDMD. Anything longer than 5000 (5ms) and you can see flicker.
 Timer1.attachInterrupt( ScanDMD ); //attach the Timer1 interrupt to ScanDMD which goes to dmd.scanDisplayBySPI() 
 dmd.clearScreen( true ); //true is normal (all pixels off), false is negative (all pixels on)

 // for MSGEQ7
 pinMode(res, OUTPUT); // reset
 pinMode(strobe, OUTPUT); // strobe
 digitalWrite(res,LOW); // reset low
 digitalWrite(strobe,HIGH); //pin 5 is RESET on the shield
}
void readMSGEQ7()
// Function to read 7 band equalizers
{
 digitalWrite(res, HIGH);
 digitalWrite(res, LOW);
 for( band = 0; band < 7; band++ )
 {
 digitalWrite(strobe,LOW); // strobe pin on the shield - kicks the IC up to the next band 
 delayMicroseconds(30); // 
 left[band] = analogRead(0); // store left band reading
 right[band] = analogRead(1); // ... and the right
 digitalWrite(strobe,HIGH); 
 }
}
void loop()
{
 int xpos;
 readMSGEQ7();
 dmd.clearScreen( true ); 
 // display values of left channel on DMD
 for( band = 0; band < 7; band++ )
 {
 xpos = (band*2)+1;
 if (left[band]>=895) { dmd.drawLine( xpos, 15, xpos, 1, GRAPHICS_NORMAL ); } else
 if (left[band]>=767) { dmd.drawLine( xpos, 15, xpos, 3, GRAPHICS_NORMAL ); } else
 if (left[band]>=639) { dmd.drawLine( xpos, 15, xpos, 5, GRAPHICS_NORMAL ); } else
 if (left[band]>=511) { dmd.drawLine( xpos, 15, xpos, 7, GRAPHICS_NORMAL ); } else
 if (left[band]>=383) { dmd.drawLine( xpos, 15, xpos, 9, GRAPHICS_NORMAL ); } else
 if (left[band]>=255) { dmd.drawLine( xpos, 15, xpos, 11, GRAPHICS_NORMAL ); } else
 if (left[band]>=127) { dmd.drawLine( xpos, 15, xpos, 13, GRAPHICS_NORMAL ); } else
 if (left[band]>=0) { dmd.drawLine( xpos, 15, xpos, 15, GRAPHICS_NORMAL ); }
 }

 // display values of right channel on DMD
 for( band = 0; band < 7; band++ )
 {
 xpos = (band*2)+18;
 if (right[band]>=895) { dmd.drawLine( xpos, 15, xpos, 1, GRAPHICS_NORMAL ); } else
 if (right[band]>=767) { dmd.drawLine( xpos, 15, xpos, 3, GRAPHICS_NORMAL ); } else
 if (right[band]>=639) { dmd.drawLine( xpos, 15, xpos, 5, GRAPHICS_NORMAL ); } else
 if (right[band]>=511) { dmd.drawLine( xpos, 15, xpos, 7, GRAPHICS_NORMAL ); } else
 if (right[band]>=383) { dmd.drawLine( xpos, 15, xpos, 9, GRAPHICS_NORMAL ); } else
 if (right[band]>=255) { dmd.drawLine( xpos, 15, xpos, 11, GRAPHICS_NORMAL ); } else
 if (right[band]>=127) { dmd.drawLine( xpos, 15, xpos, 13, GRAPHICS_NORMAL ); } else
 if (right[band]>=0) { dmd.drawLine( xpos, 15, xpos, 15, GRAPHICS_NORMAL ); }
 }
}

… and here it is in action:

Conclusion

At this point you have the knowledge to use the MSGEQ7 ICs to create some interesting spectrum analysers for entertainment and visual appeal – now you just choose the type of display enjoy the results. 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”.

The post Tutorial: Arduino and the MSGEQ7 Spectrum Analyzer appeared first on tronixstuff.

This hexapod was made almost entirely via 3d printing (translated). The parts that you need to supply include a few fasteners to make connections, twelve servo motors, and a method of driving them. As you can see in the video after the break, all those parts come together into a little robot that functions quite well. The only thing that we think is missing are some grippy feet to help prevent slipping.

[Hugo] calls the project Bleuette. It is completely open source, with the cad files and source code available on his Github repository. There is additional information in the wiki page of that repo. This gives us a good look at the electronic design. He’s controlling the legs with an Arduino, but it’s all dependent on his own shield which features a PIC 18F452 to take care of the signals used to drive all of the servo motors. The board also has some peripherals to monitor the current draw and regulate the incoming power.

A while ago, I got hold of a car alarm unit and its two remote control fobs. When i hooked it up to 12V I realized that it didn’t  work, not responding to any of the commands from the two fobs even though their batteries were OK. Naturally, I opened up the unit to start harvesting parts and noticed the RF module within (the one that sticks out perpendicularly) and I figured it shouldn’t be too hard to use the module with an Arduino.

read more

7 different shades of RGB LED.. Enjoy watching it..

Read the full article on MAKE

Thats the code that i typed.... The result was red green blue red green-blue red(for a longer period)

And that keeps on repeating.....

But what i actually want is red green blue red-green green-blue red-blue white   And this should repeat....  

int red=12;

int green=8;

int blue=7;

void setup(){

  pinMode(red,OUTPUT);

  pinMode(green,OUTPUT);

  pinMode(blue,OUTPUT);

}

void loop(){

  digitalWrite(red,LOW);

  digitalWrite(green,HIGH);

read more

Hi everyone,

Recently I came across some very good hexapods designed with 6,8 and even 12 servos.I have a duemilanove and would like to build one.

But unfortunately I have not ventured into this domain and my search for a step by step tutorial on google(on multilegged critters like hexapod) and instructables proved futile.Any Links that can help me get started or rather a complete tutorial link would be awesome.Thanks!

This telepresence upgrade lets an employee take part in the office from more than four thousand kilometers away. It’s an upgrade of their previous setup which used a laptop on a rotating platform to add a bit of control to the video conferencing experience. But all that original version could do was swivel, this one lets you drive your virtual self around for fifteen hours between battery charges.

The real work is in the base of the robot, as the audio and video are handled by a tablet independently from the locomotion. The team spent about four hundred bucks to throw the thing together. It starts with a hunk of plywood. Two 3A motors were mated with lawnmower wheels for the front of the bot. Dragging under the back of the base are a couple of casters that make it possible to turn without skidding. A motor shield and a WiFi shield for the Arduino make it possible to control the thing over the Internet. They even added some functionality on the client side to use a PlayStation 3 controller. Check out the completed machine in the clip after the break.