Arduino Sketch Adafruit PWM

This sketch is used by Exercise: Adafruit PWM I2C Module.

Full Source Code

The main code is in Adafruit_PWM.ino.

/*************************************************** 
  This is an example for our Adafruit 16-channel PWM & Servo driver
  PWM test - this will drive 16 PWMs in a 'wave'

  Pick one up today in the adafruit shop!
  ------> http://www.adafruit.com/products/815

  These displays use I2C to communicate, 2 pins are required to  
  interface. For Arduino UNOs, thats SCL -> Analog 5, SDA -> Analog 4

  Adafruit invests time and resources providing this open source code, 
  please support Adafruit and open-source hardware by purchasing 
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries.  
  BSD license, all text above must be included in any redistribution
 ****************************************************/

#include <Wire.h>
// #include <Adafruit_PWMServoDriver.h>
#include "Adafruit_PWMServoDriver.h"

// called this way, it uses the default address 0x40
Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver();
// you can also call it with a different address you want
//Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver(0x41);

void setup() {
  Serial.begin(9600);
  Serial.println("16 channel PWM test!");

  // if you want to really speed stuff up, you can go into 'fast 400khz I2C' mode
  // some i2c devices dont like this so much so if you're sharing the bus, watch
  // out for this!

  pwm.begin();
  pwm.setPWMFreq(1600);  // This is the maximum PWM frequency
    
  // save I2C bitrate
  uint8_t twbrbackup = TWBR;
  // must be changed after calling Wire.begin() (inside pwm.begin())
  TWBR = 12; // upgrade to 400KHz!
    
}

void loop() {
  // Drive each PWM in a 'wave'
  for (uint16_t i=0; i<4096; i += 8) {
    for (uint8_t pwmnum=0; pwmnum < 16; pwmnum++) {
      pwm.setPWM(pwmnum, 0, (i + (4096/16)*pwmnum) % 4096 );
    }
  }
}

The supporting code is in Adafruit_PWM.ino.

/*************************************************** 
  This is a library for our Adafruit 16-channel PWM & Servo driver

  Pick one up today in the adafruit shop!
  ------> http://www.adafruit.com/products/815

  These displays use I2C to communicate, 2 pins are required to  
  interface. For Arduino UNOs, thats SCL -> Analog 5, SDA -> Analog 4

  Adafruit invests time and resources providing this open source code, 
  please support Adafruit and open-source hardware by purchasing 
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries.  
  BSD license, all text above must be included in any redistribution
 ****************************************************/

// #include <Adafruit_PWMServoDriver.h>
#include "Adafruit_PWMServoDriver.h"
#include <Wire.h>
#if defined(__AVR__)
 #define WIRE Wire
#elif defined(CORE_TEENSY) // Teensy boards
 #define WIRE Wire
#else // Arduino Due
 #define WIRE Wire1
#endif

// Set to true to print some debug messages, or false to disable them.
#define ENABLE_DEBUG_OUTPUT true

Adafruit_PWMServoDriver::Adafruit_PWMServoDriver(uint8_t addr) {
  _i2caddr = addr;
}

void Adafruit_PWMServoDriver::begin(void) {
 WIRE.begin();
 reset();
}


void Adafruit_PWMServoDriver::reset(void) {
 write8(PCA9685_MODE1, 0x0);
}

void Adafruit_PWMServoDriver::setPWMFreq(float freq) {
  //Serial.print("Attempting to set freq ");
  //Serial.println(freq);
  freq *= 0.9;  // Correct for overshoot in the frequency setting (see issue #11).
  float prescaleval = 25000000;
  prescaleval /= 4096;
  prescaleval /= freq;
  prescaleval -= 1;
  if (ENABLE_DEBUG_OUTPUT) {
    Serial.print("Estimated pre-scale: "); Serial.println(prescaleval);
  }
  uint8_t prescale = floor(prescaleval + 0.5);
  if (ENABLE_DEBUG_OUTPUT) {
    Serial.print("Final pre-scale: "); Serial.println(prescale);
  }
  
  uint8_t oldmode = read8(PCA9685_MODE1);
  uint8_t newmode = (oldmode&0x7F) | 0x10; // sleep
  write8(PCA9685_MODE1, newmode); // go to sleep
  write8(PCA9685_PRESCALE, prescale); // set the prescaler
  write8(PCA9685_MODE1, oldmode);
  delay(5);
  write8(PCA9685_MODE1, oldmode | 0xa1);  //  This sets the MODE1 register to turn on auto increment.
                                          // This is why the beginTransmission below was not working.
  //  Serial.print("Mode now 0x"); Serial.println(read8(PCA9685_MODE1), HEX);
}

void Adafruit_PWMServoDriver::setPWM(uint8_t num, uint16_t on, uint16_t off) {
  //Serial.print("Setting PWM "); Serial.print(num); Serial.print(": "); Serial.print(on); Serial.print("->"); Serial.println(off);

  WIRE.beginTransmission(_i2caddr);
  WIRE.write(LED0_ON_L+4*num);
  WIRE.write(on);
  WIRE.write(on>>8);
  WIRE.write(off);
  WIRE.write(off>>8);
  WIRE.endTransmission();
}

// Sets pin without having to deal with on/off tick placement and properly handles
// a zero value as completely off.  Optional invert parameter supports inverting
// the pulse for sinking to ground.  Val should be a value from 0 to 4095 inclusive.
void Adafruit_PWMServoDriver::setPin(uint8_t num, uint16_t val, bool invert)
{
  // Clamp value between 0 and 4095 inclusive.
  val = min(val, 4095);
  if (invert) {
    if (val == 0) {
      // Special value for signal fully on.
      setPWM(num, 4096, 0);
    }
    else if (val == 4095) {
      // Special value for signal fully off.
      setPWM(num, 0, 4096);
    }
    else {
      setPWM(num, 0, 4095-val);
    }
  }
  else {
    if (val == 4095) {
      // Special value for signal fully on.
      setPWM(num, 4096, 0);
    }
    else if (val == 0) {
      // Special value for signal fully off.
      setPWM(num, 0, 4096);
    }
    else {
      setPWM(num, 0, val);
    }
  }
}

uint8_t Adafruit_PWMServoDriver::read8(uint8_t addr) {
  WIRE.beginTransmission(_i2caddr);
  WIRE.write(addr);
  WIRE.endTransmission();

  WIRE.requestFrom((uint8_t)_i2caddr, (uint8_t)1);
  return WIRE.read();
}

void Adafruit_PWMServoDriver::write8(uint8_t addr, uint8_t d) {
  WIRE.beginTransmission(_i2caddr);
  WIRE.write(addr);
  WIRE.write(d);
  WIRE.endTransmission();
}

The supporting definitions are in Adafruit_PWM.ino.

/*************************************************** 
  This is a library for our Adafruit 16-channel PWM & Servo driver

  Pick one up today in the adafruit shop!
  ------> http://www.adafruit.com/products/815

  These displays use I2C to communicate, 2 pins are required to  
  interface. For Arduino UNOs, thats SCL -> Analog 5, SDA -> Analog 4

  Adafruit invests time and resources providing this open source code, 
  please support Adafruit and open-source hardware by purchasing 
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries.  
  BSD license, all text above must be included in any redistribution
 ****************************************************/

#ifndef _ADAFRUIT_PWMServoDriver_H
#define _ADAFRUIT_PWMServoDriver_H

#if ARDUINO >= 100
 #include "Arduino.h"
#else
 #include "WProgram.h"
#endif


#define PCA9685_SUBADR1 0x2
#define PCA9685_SUBADR2 0x3
#define PCA9685_SUBADR3 0x4

#define PCA9685_MODE1 0x0
#define PCA9685_PRESCALE 0xFE

#define LED0_ON_L 0x6
#define LED0_ON_H 0x7
#define LED0_OFF_L 0x8
#define LED0_OFF_H 0x9

#define ALLLED_ON_L 0xFA
#define ALLLED_ON_H 0xFB
#define ALLLED_OFF_L 0xFC
#define ALLLED_OFF_H 0xFD


class Adafruit_PWMServoDriver {
 public:
  Adafruit_PWMServoDriver(uint8_t addr = 0x40);
  void begin(void);
  void reset(void);
  void setPWMFreq(float freq);
  void setPWM(uint8_t num, uint16_t on, uint16_t off);
  void setPin(uint8_t num, uint16_t val, bool invert=false);

 private:
  uint8_t _i2caddr;

  uint8_t read8(uint8_t addr);
  void write8(uint8_t addr, uint8_t d);
};

#endif

Source: Arduino Sketch Adafruit PWM