arduino_engine.c

#include <Wire.h>

#if defined(ARDUINO_SAM_DUE)
 #define WIRE Wire1
#else
 #define WIRE Wire
#endif

//Settings:
#define _i2caddr 0x60

//??
#define LED0_ON_L 0x6
#define PCA9685_MODE1 0x0
#define PCA9685_PRESCALE 0xFE

void setup() {
  Serial.begin(9600);// set up Serial library at 9600 bps
  Serial.println("Adafruit Motorshield v2 - DC Motor test!");

  WIRE.begin();
  reset();
  setPWMFreq(0);

  //turn off all pins
  for (uint8_t i=0; i<16; i++) {
    setPWM(i, 0, 0);
  }

  //Stop everything..
  setPWM(8, 0, 0);
  setPin(10, LOW);
  setPin(9, LOW);
}

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

void 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;
  Serial.print("Estimated pre-scale: "); Serial.println(prescaleval);
  uint8_t prescale = floor(prescaleval + 0.5);
  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);
}

uint8_t read8(uint8_t addr) {
  WIRE.beginTransmission(_i2caddr);
#if ARDUINO >= 100
  WIRE.write(addr);
#else
  WIRE.send(addr);
#endif
  WIRE.endTransmission();

  WIRE.requestFrom((uint8_t)_i2caddr, (uint8_t)1);
#if ARDUINO >= 100
  return WIRE.read();
#else
  return WIRE.receive();
#endif
}

void write8(uint8_t addr, uint8_t d) {
  WIRE.beginTransmission(_i2caddr);
#if ARDUINO >= 100
  WIRE.write(addr);
  WIRE.write(d);
#else
  WIRE.send(addr);
  WIRE.send(d);
#endif
  WIRE.endTransmission();
}

void setPWM(uint8_t num, uint16_t on, uint16_t 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();
}

void setPin(uint8_t pin, boolean value) {
  if (value == LOW)
    setPWM(pin, 0, 0);
  else
    setPWM(pin, 4096, 0);
}


void loop() {
  //run it
  setPWM(8, 150*16, 0);
  setPin(9, LOW);  // take low first to avoid 'break'
  setPin(10, HIGH);

  delay(1000);//pause

  setPin(10, LOW);  // take low first to avoid 'break'
  setPin(9, HIGH);

  delay(1000);//pause

  //turn off
  setPWM(8, 0, 0);
  setPin(10, LOW);
  setPin(9, LOW);

  delay(5000);//pause
}