Posts with «pwm» label

Arduino Powered Arcade Button Lighting Effects

As if you already weren’t agonizing over whether or not you should build your own arcade cabinet, add this one to the list of compelling reasons why you should dedicate an unreasonable amount of physical space to playing games you’ve probably already got emulated on your phone. [Rodrigo] writes in to show off his project to add some flair to the lighted buttons on his arcade controller. (Google Translate)

The wiring for this project is about as easy as you’d expect: the buttons connect to the digital inputs on the Arduino, and the LEDs on the digital outputs. When the Arduino code sees the button getting pressed, it brings the corresponding LED pin high and starts a fade out timer using the SoftPWM library by [Brett Hagman].

It’s worth noting that the actual USB interface is being done with a stand-alone controller, so the Arduino here is being used purely to drive the lighting effects. The more critical reader might argue that you could do both with a single microcontroller, but [Rodrigo] was in a classic “Use what you’ve got” situation, and already had a USB controller on hand.

Of course, fancy lit arcade buttons won’t do you much good without something to put them in. Luckily we’ve covered some fantastic looking arcade cabinets to get you inspired.

Hack a Day 20 Jul 21:00

Need a Thousand Extra PWM Pins?

If your Arduino runs out of I/O lines, you can always add one of the several I/O expander chips that takes a serial interface to set its several pins. Or perhaps you could buy something like an Arduino Mega, with its extra sockets to fulfil your needs. But what would you do if you really needed more pins, say a thousand of them? Perhaps [Brian Lough] has the answer. OK, full disclosure: If you really need a thousand, the video isn’t exactly for you, as he shows you how to add up to 992 PWM outputs. The chip he uses works with any microcontroller (the video shows an ESP8266), and we suppose you could use two daisy chains of them and break the 1,000 barrier handily.

We like how short the video is (just two minutes; see below) as it gets right to the point. The PCA9685 chip gives you 16 12-bit PWM channels via an I2C interface. You can daisy chain up to 62 of the boards to get the 992 outputs promised.

[Brian] uses a cheap $2 breakout board that lets you set a 6-bit address, has a nice power connector and makes it easy to use the little surface mount device. Each of the 16 outputs on the board can have an independent duty cycle, but they do share a single output frequency. That means if you want to use some channels for low-frequency devices like motors and some for high-frequency devices like LEDs, you might have to spring $4 for two boards.

Over on Hackaday.io, we’ve seen these devices driving 128 vibration motors. The PCA9685 made us think of the time we rolled our own serial to PWM devices using an FPGA.

Hack a Day 12 Apr 00:00

Roll Your Own Arduino PWM

Most projects are built on abstractions. After all, few of us can create our own wire, our own transistors, or our own integrated circuits. A few months ago, [Julian Ilett] found a problem using the Arduino library for PWM. Recently, he revisited the issue and used his own PWM code to fix the problem. You can watch the video below.

Of course, neither the Arduino library nor [Julian’s] code is actually producing PWM. The Atmel CPU’s hardware is doing the work. The Arduino library gives you a wrapper called analogWrite — especially handy if you are not using an Atmel CPU where the same abstraction will do the same work. The issue arose when [Julian] broke the abstraction to invert the PWM output.

The video does a good job of framing the issue. Setting the PWM hardware to zero still causes a one tick output to occur. That is, the actual count is the count you supply plus one. That’s great on the high end where 255 is treated as 256 out of 256. But at the low end, a zero counterintuitively gives you 1/256. The Arduino library authors elected to detect that edge case and just force the output pin to go low in that case. When inverted, however, the pin still goes low when it ought to go high. You can see the source code responsible, below.

pinMode(pin, OUTPUT);
if (val == 0)
  {
  digitalWrite(pin, LOW);
  }
else if (val == 255)
  {
  digitalWrite(pin, HIGH);
  }
else
{ ...

Oddly, the 255 case appears to be superfluous in the normal case but is also backward if you invert the output. In all fairness, the Arduino library doesn’t provide you a way to invert the output, so you’ve already broken the abstraction and that’s why this isn’t technically a bug in the library.

[Julian’s] code is quite simple. There’s initial set up of the TCCR1A and TCCR1B registers along with ICR1. The DDRB register sets the pin as an output. After that, writing to OCR1A and OCR1B set the PWM value. The video explains it all in great detail.

We’ve looked at PWM on FPGAs at least once, and that post gives some background on PWM in any application. We also have our own video from way back in 2011 about PWM.


Filed under: Arduino Hacks
Hack a Day 12 Nov 12:00

Scrap Bin Mods Move Science Forward

A first-time visitor to any bio or chem lab will have many wonders to behold, but few as captivating as the magnetic stirrer. A motor turns a magnet which in turn spins a Teflon-coated stir bar inside the beaker that sits on top. It’s brilliantly simple and so incredibly useful that it leaves one wondering why they’re not included as standard equipment in every kitchen range.

But as ubiquitous as magnetic stirrers are in the lab, they generally come in largish packages. [BantamBasher135] needed a much smaller stir plate to fit inside a spectrophotometer. With zero budget, he retrofitted the instrument with an e-waste, Arduino-controlled magnetic stirrer.

The footprint available for the modification was exceedingly small — a 1 cm square cuvette with a flea-sized micro stir bar. His first stab at the micro-stirrer used a tiny 5-volt laptop fan with the blades cut off and a magnet glued to the hub, but that proved problematic. Later improvements included beefing up the voltage feeding the fan and coming up with a non-standard PWM scheme to turn the motor slow enough to prevent decoupling the stir bar from the magnets.

[BantamBasher135] admits that it’s an ugly solution, but one does what one can to get the science done. While this is a bit specialized, we’ve featured plenty of DIY lab instruments here before. You can make your own peristaltic pump or even a spectrophotometer — with or without the stirrer.

[via r/Arduino]


Filed under: chemistry hacks, tool hacks

Primer on Servos Hits All the Basics

Servos are pretty basic fare for the seasoned hacker. But everyone has to start somewhere, and there’s sure to be someone who’ll benefit from this primer on servo internals. Who knows – maybe even the old hands will pick up something from a fresh perspective.

[GreatScott!] has been building a comprehensive library of basic electronics videos over the last few years that covers everything from using a multimeter to programming an Arduino. The last two installments delve into the electromechanical realm with a treatment of stepper motors along with the servo video below. He covers the essentials of the modern RC-type servo in a clear and engaging style that makes it easy for the newbie to understand how a PWM signal can translate into positional changes over a 180° sweep. He shows how to control a servo directly with an Arduino, with bonus points for including a simple 555-based controller circuit too. A quick look at the mods needed to convert any servo to continuous rotation wraps up the video.

If [GreatScott!]’s video whets your appetite for more, be sure to check out [Richard Baguley]’s deeper dive into servos. And when you’re ready to put your new-found knowledge into practice, maybe a nice project would be to convert a hobby servo into a linear actuator.


Filed under: classic hacks, misc hacks

Smart street light using arduino

Introduction:

This project is about smart street light using arduino. This project consists of 3 analog IR (infrared) sensors. By default, the intensity of street light is set to 50 percent. We are using high intensity led as they have extra brightness. This project also features harnessing the solar and wind energy.
We are using a solar panel of  9 Volt, 2.5 watts and for wind mill, we are simply using a 12 volt dc motor.

Components required:
  1. Atmega 8a (based on arduino ng board)
  2. 8 high-intensity led
  3. Relay
  4. Perfboard
  5. 7805
  6. connecting wires
  7. solar panel (9 volt, 2.5 watt)
  8. Relay
  9. 12 volt DC motor.
How it works:

By default, the intensity of high intensity light (aka street light) is set to 50% pwm. We are using three channel of PWM. The first channel of pwm is controlling three leds, second channel is used for controlling two led's whereas the third channel is used for controlling three led at once. There are eight high intensity led. There are three, analog IR sensor, which can detect the vehicle. Upon detection of vehicle by the first sensor, it will increase the duty cycle of first three led's to 100% and by this the intensity of first three led will increase. Now, when vehicle reaches near second IR sensor first three led will again set to 50% duty cycle whereas the next two led will set to 100% duty cycle. 


IR sensor:

IR sensor is made up of simply IR led and photodiode. The connection is as follows:

DIY IR sensor

Check out the video:



Stay tuned for more updates !!






FunWithElectronics 14 Oct 05:08

8-bit volume control for Arduino tone()

Connor Nishijima has devised a neat trick to give the standard Arduino Tone() function 256 smooth volume levels using PWM at an ultrasonic frequency, without any extra components. This allows for programmatic control of square waves with nothing other than a speaker connected to an Arduino Uno.

Normally to simulate an analog voltage with a digital-only pin of a microcontroller you’d use Pulse Width Modulation. This works great for LEDs because your eyes can’t the 490 / 976Hz flicker of the standard analogWrite() function. But for audio things are a bit more difficult. Because your ears can easily detect frequencies between 20 – 20,000Hz, any PWM with a frequency in this range is out.

Luckily, the ATmega328P allows you to change the clock prescalers for ultrasonic PWM! We need to use Timer0, because it can drive PWM at a max frequency of 62,500Hz, which even if you cut that in half would still be above your hearing range. Now that we have ultrasonic PWM on Pins 5 & 6, we configure Timer1 to fire an Interrupt Service Routine at a rate of “desired frequency” * 2.

Finally, inside the Timer1 ISR routine, we incorporate our volume trick. Instead of digitalWrite()’ing the pin HIGH and LOW like the normal Tone() function does, we analogWrite() “HIGH” with our volume value (0 – 255) and analogWrite(0) for “LOW”. Because of how fast the PWM is running, the user doesn’t hear the 62.5KHz PWM frequency, and instead perceives a 50% percent duty cycle as a speaker driven with only 2.5 volts! While a few volume levels do produce subtle artifacts to the sound, it mostly delivers quality 8-bit volume control to replace the standard Tone() function.

When all is said and done, you’ll be able to customize your project with unique loudness as you play anything from the iconic Nintendo sound to R2-D2’s beeps and bops. In Nishijima’s case, he developed this Arduino volume-control scheme to make an incessant, inconsistent artificial cricket to hide in a friend’s vent for the next few months… You can read more on its Hackaday.io page, as well as find documentation and ready-to-use example sketches GitHub.

Arduino Blog 13 Jun 13:48

Temperature controlled dc fan

In this post, we will control the speed of dc fan based on the temperature.

List of components:

1. Arduino Uno
2. LM 35 temperature sensor
3. LCD 16*2
4. 10k potentiometer
5. ULN 2003
6. DC motor
7. Breadboard/ perfboard

First of all, we will monitor the temperature by using lm35 i.e. temperature sensor. It's scale factor is +10mV/°C which means with increment in temperature by 1° Celsius, the voltage is rise by 10 mV.
We can read adc count by analogRead(A0); // we are using channel A0

This will give us a digital count of adc which varies from 0 to 1023, we have to convert these count into voltage and then into temperature. First of all, we will convert into voltage:
In arduino uno, adc is of 10-bit.
Resolution = Vref/(2^n-1), where n is bit (in our case it's 10)
Resolution = 5000 / 1023, ( Verf = 5000 mV and 2^10 is 1024 minus 1 is 1023)

Resolution = 4.887 mV
Now, we have to convert voltage into temperature:
Temperature (in °C) = Voltage (in mV) / 10.0
With this temperature monitoring is over.

LCD interfacing is simple since we have library for the same with proper documentation.

Now coming to pwm part. In arduino, we can control output voltage by pulse width modulation (pwm).
Duty Cycle = Ton / (Ton + Toff)
Duty Cycle = Ton / T

Duty Cycle (in %age) = (Ton / T)*100

In arduino, for pwm we have analogWrite function :

In arduino uno, we have six pwm channels viz, pin no. 3, 5, 6, 9, 10 and 11.

analogWrite(pin no, value)

Pin no may be 3, 5, 6, 9, 10 and 11
Value varies from 0 to 255 since pwm resolution is of 8-bit (2^8-1)

0 for 0% duty cycle                  0 volts
64 for 25% duty cycle              1.25 volts            if(val<=40.0)
127 for 50% duty cycle            2.50 volts            if(val>40.0 && val<=50.0)
192 for 75% duty cycle            3.75 volts            if(val>50.0 && val<=60.0)
255 for 100% duty cycle          5.00 volts            if(val>60.0)

where val is temperature in °C

Vavg = Duty Cycle  * 5.0 volts
 
Schematic of temperature controlled fan
Download the source code from the link below:


Stay tuned for more updates !!





Send HEX values to Arduino

FIVE MINUTE TUTORIAL

Project Description: Sending Hex values to an Arduino UNO


This simple tutorial will show you how to send Hexadecimal values from a computer to an Arduino Uno. The "Processing" programming language will be used to send the HEX values from the computer when a mouse button is pressed. The Arduino will use these values to adjust the brightness of an LED.



 

Learning Objectives


  • To Send Hexadecimal (Hex) values from a computer to the Arduino
  • Trigger an action based on the press of a mouse button
  • Learn to create a simple Computer to Arduino interface
  • Use Arduino's PWM capabilities to adjust brightness of an LED
  • Learn to use Arduino's analogWrite() function
  • Create a simple LED circuit


 

Parts Required:


Fritzing Sketch


The diagram below will show you how to connect an LED to Digital Pin 10 on the Arduino.
Don't forget the 330 ohm resistor !
 


 
 

Arduino Sketch


The latest version of Arduino IDE can be downloaded here.
 
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/* ==================================================================================================================================================
         Project: 5 min tutorial: Send Hex from computer to Arduino
          Author: Scott C
         Created: 21th June 2015
     Arduino IDE: 1.6.4
         Website: http://arduinobasics.blogspot.com/p/arduino-basics-projects-page.html
     Description: Arduino Sketch used to adjust the brightness of an LED based on the values received
                  on the serial port. The LED needs to be connected to a PWM pin. In this sketch
                  Pin 10 is used, however you could use Pin 3, 5, 6, 9, or 11 - if you are using an Arduino Uno.
===================================================================================================================================================== */

byte byteRead; //Variable used to store the byte received on the Serial Port
int ledPin = 10; //LED is connected to Arduino Pin 10. This pin must be PWM capable.

void setup() {
 Serial.begin(9600); //Initialise Serial communication with the computer
 pinMode(ledPin, OUTPUT); //Set Pin 10 as an Output pin
 byteRead = 0;                   //Initialise the byteRead variable to zero.
}

void loop() {
  if(Serial.available()) {
    byteRead = Serial.read(); //Update the byteRead variable with the Hex value received on the Serial COM port.
  }
  
  analogWrite(ledPin, byteRead); //Use PWM to adjust the brightness of the LED. Brightness is determined by the "byteRead" variable.
}


 


 
 

Processing Sketch


The latest version of the Processing IDE can be downloaded here.
 
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/* ==================================================================================================================================================
         Project: 5 min tutorial: Send Hex from computer to Arduino
          Author: Scott C
         Created: 21th June 2015
  Processing IDE: 2.2.1
         Website: http://arduinobasics.blogspot.com/p/arduino-basics-projects-page.html
     Description: Processing Sketch used to send HEX values from computer to Arduino when the mouse is pressed.
                  The alternating values 0xFF and 0x00 are sent to the Arduino Uno to turn an LED on and off.
                  You can send any HEX value from 0x00 to 0xFF. This sketch also shows how to convert Hex strings
                  to Hex numbers.
===================================================================================================================================================== */

import processing.serial.*; //This import statement is required for Serial communication

Serial comPort;                       //comPort is used to write Hex values to the Arduino
boolean toggle = false; //toggle variable is used to control which hex variable to send
String zeroHex = "00"; //This "00" string will be converted to 0x00 and sent to Arduino to turn LED off.
String FFHex = "FF"; //This "FF" string will be converted to 0xFF and sent to Arduino to turn LED on.

void setup(){
    comPort = new Serial(this, Serial.list()[0], 9600); //initialise the COM port for serial communication at a baud rate of 9600.
    delay(2000);                      //this delay allows the com port to initialise properly before initiating any communication.
    background(0); //Start with a black background.
    
}


void draw(){ //the draw() function is necessary for the sketch to compile
    //do nothing here //even though it does nothing.
}


void mousePressed(){ //This function is called when the mouse is pressed within the Processing window.
  toggle = ! toggle;                   //The toggle variable will change back and forth between "true" and "false"
  if(toggle){ //If the toggle variable is TRUE, then send 0xFF to the Arduino
     comPort.write(unhex(FFHex)); //The unhex() function converts the "FF" string to 0xFF
     background(0,0,255); //Change the background colour to blue as a visual indication of a button press.
  } else {
    comPort.write(unhex(zeroHex)); //If the toggle variable is FALSE, then send 0x00 to the Arduino
    background(0); //Change the background colour to black as a visual indication of a button press.
  }
}


 

The Video


 

The tutorial above is a quick demonstration of how to convert Hex strings on your computer and send them to an Arduino. The Arduino can use the values to change the brightness of an LED as shown in this tutorial, however you could use it to modify the speed of a motor, or to pass on commands to another module. Hopefully this short tutorial will help you with your project. Please let me know how it helped you in the comments below.

 
 



If you like this page, please do me a favour and show your appreciation :

 
Visit my ArduinoBasics Google + page.
Follow me on Twitter by looking for ScottC @ArduinoBasics.
I can also be found on Pinterest and Instagram.
Have a look at my videos on my YouTube channel.


 
 
             


 
 



However, if you do not have a google profile...
Feel free to share this page with your friends in any way you see fit.

Send HEX values to Arduino

FIVE MINUTE TUTORIAL

Project Description: Sending Hex values to an Arduino UNO


This simple tutorial will show you how to send Hexadecimal values from a computer to an Arduino Uno. The "Processing" programming language will be used to send the HEX values from the computer when a mouse button is pressed. The Arduino will use these values to adjust the brightness of an LED.



 

Learning Objectives


  • To Send Hexadecimal (Hex) values from a computer to the Arduino
  • Trigger an action based on the press of a mouse button
  • Learn to create a simple Computer to Arduino interface
  • Use Arduino's PWM capabilities to adjust brightness of an LED
  • Learn to use Arduino's analogWrite() function
  • Create a simple LED circuit


 

Parts Required:


Fritzing Sketch


The diagram below will show you how to connect an LED to Digital Pin 10 on the Arduino.
Don't forget the 330 ohm resistor !
 


 
 

Arduino Sketch


The latest version of Arduino IDE can be downloaded here.
 
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/* ==================================================================================================================================================
         Project: 5 min tutorial: Send Hex from computer to Arduino
          Author: Scott C
         Created: 21th June 2015
     Arduino IDE: 1.6.4
         Website: http://arduinobasics.blogspot.com/p/arduino-basics-projects-page.html
     Description: Arduino Sketch used to adjust the brightness of an LED based on the values received
                  on the serial port. The LED needs to be connected to a PWM pin. In this sketch
                  Pin 10 is used, however you could use Pin 3, 5, 6, 9, or 11 - if you are using an Arduino Uno.
===================================================================================================================================================== */

byte byteRead; //Variable used to store the byte received on the Serial Port
int ledPin = 10; //LED is connected to Arduino Pin 10. This pin must be PWM capable.

void setup() {
 Serial.begin(9600); //Initialise Serial communication with the computer
 pinMode(ledPin, OUTPUT); //Set Pin 10 as an Output pin
 byteRead = 0;                   //Initialise the byteRead variable to zero.
}

void loop() {
  if(Serial.available()) {
    byteRead = Serial.read(); //Update the byteRead variable with the Hex value received on the Serial COM port.
  }
  
  analogWrite(ledPin, byteRead); //Use PWM to adjust the brightness of the LED. Brightness is determined by the "byteRead" variable.
}


 


 
 

Processing Sketch


The latest version of the Processing IDE can be downloaded here.
 
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/* ==================================================================================================================================================
         Project: 5 min tutorial: Send Hex from computer to Arduino
          Author: Scott C
         Created: 21th June 2015
  Processing IDE: 2.2.1
         Website: http://arduinobasics.blogspot.com/p/arduino-basics-projects-page.html
     Description: Processing Sketch used to send HEX values from computer to Arduino when the mouse is pressed.
                  The alternating values 0xFF and 0x00 are sent to the Arduino Uno to turn an LED on and off.
                  You can send any HEX value from 0x00 to 0xFF. This sketch also shows how to convert Hex strings
                  to Hex numbers.
===================================================================================================================================================== */

import processing.serial.*; //This import statement is required for Serial communication

Serial comPort;                       //comPort is used to write Hex values to the Arduino
boolean toggle = false; //toggle variable is used to control which hex variable to send
String zeroHex = "00"; //This "00" string will be converted to 0x00 and sent to Arduino to turn LED off.
String FFHex = "FF"; //This "FF" string will be converted to 0xFF and sent to Arduino to turn LED on.

void setup(){
    comPort = new Serial(this, Serial.list()[0], 9600); //initialise the COM port for serial communication at a baud rate of 9600.
    delay(2000);                      //this delay allows the com port to initialise properly before initiating any communication.
    background(0); //Start with a black background.
    
}


void draw(){ //the draw() function is necessary for the sketch to compile
    //do nothing here //even though it does nothing.
}


void mousePressed(){ //This function is called when the mouse is pressed within the Processing window.
  toggle = ! toggle;                   //The toggle variable will change back and forth between "true" and "false"
  if(toggle){ //If the toggle variable is TRUE, then send 0xFF to the Arduino
     comPort.write(unhex(FFHex)); //The unhex() function converts the "FF" string to 0xFF
     background(0,0,255); //Change the background colour to blue as a visual indication of a button press.
  } else {
    comPort.write(unhex(zeroHex)); //If the toggle variable is FALSE, then send 0x00 to the Arduino
    background(0); //Change the background colour to black as a visual indication of a button press.
  }
}


 

The Video


 

The tutorial above is a quick demonstration of how to convert Hex strings on your computer and send them to an Arduino. The Arduino can use the values to change the brightness of an LED as shown in this tutorial, however you could use it to modify the speed of a motor, or to pass on commands to another module. Hopefully this short tutorial will help you with your project. Please let me know how it helped you in the comments below.

 
 



If you like this page, please do me a favour and show your appreciation :

 
Visit my ArduinoBasics Google + page.
Follow me on Twitter by looking for ScottC @ArduinoBasics.
I can also be found on Pinterest and Instagram.
Have a look at my videos on my YouTube channel.


 
 
             


 
 



However, if you do not have a google profile...
Feel free to share this page with your friends in any way you see fit.