File content as of revision 2:eb4b8670523a:

#include <mbed.h>
#include "PCA9685.h"
#define i2c_addr 0x80
I2C i2c(p9,p10);
Serial pc(USBTX,USBRX);

//PCA9685::PCA9685(uint8_t addr) {
//  i2c_addr = addr;
//}

void PCA9685::begin(void) {
// WIRE.begin();
 reset();
}

void PCA9685::reset(void) {
 write8(PCA9685_MODE1, 0x0);
}

void PCA9685::setPWMFreq(float freq) {  
  float prescaleval = 25000000;
  prescaleval /= 4096;
  prescaleval /= freq;
  prescaleval -= 1;
  uint8_t prescale = floor(prescaleval + 0.5);
  uint8_t oldreg = read8(PCA9685_MODE1);
  //pc.printf("oldreg=%02X , ",oldreg);
  uint8_t newreg = (oldreg&0x7F) | 0x10; // sleep
  write8(PCA9685_MODE1, newreg); // go to sleep
  wait_ms(5);
  write8(PCA9685_PRESCALE, prescale); // set the prescaler
  write8(PCA9685_MODE1, oldreg);
  wait_ms(5);
  write8(PCA9685_MODE1, oldreg | 0xa1);  //  This sets the MODE1 register to turn on auto increment.
}

void PCA9685::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);
  //int ded;
  char cmd[5];//WIRE.beginTransmission(i2c_addr);
  cmd[0]=LED0_ON_L+4*num;//WIRE.write(LED0_ON_L+4*num);
  cmd[1]=on&0xFF;//WIRE.write(on);
  cmd[2]=on>>8;//WIRE.write(on>>8);
  cmd[3]=off&0xFF;//WIRE.write(off);
  cmd[4]=off>>8;//WIRE.write(off>>8);
  i2c.write(i2c_addr,cmd,5);//WIRE.endTransmission();
  //pc.printf("write 5 %d\r\n",ded);
}

void PCA9685::write8(uint8_t addr, uint8_t d) {
  //int val;
  char cmd[2];//WIRE.beginTransmission(i2c_addr);
  cmd[0]=addr;//WIRE.write(addr);
  cmd[1]=d;//WIRE.write(d);
  i2c.write(i2c_addr,cmd,2);//WIRE.endTransmission();
  //pc.printf("write %d\r\n",val);
}

uint8_t PCA9685::read8(uint8_t addr) {
  //int val;
  char cmd[1];                   //WIRE.beginTransmission(i2c_addr);
  cmd[0]=addr;
  i2c.write(i2c_addr,cmd,1);   //WIRE.write(addr);
                                      //WIRE.endTransmission();
  //pc.printf("write %d\r\n",val);
  char rtn[1];
  i2c.read(i2c_addr,rtn,1);    //WIRE.requestFrom((uint8_t)i2c_addr, (uint8_t)1);
  //pc.printf("read %d %c\r\n",val,rtn[0]);
  return rtn[0];                        //return WIRE.read();
}