#include <Arduino.h>

#define pin  PA8

#define maxSamples 1
#define PWM_OVERFLOW 18000

char sinetable [32];

uint16_t buffer[maxSamples];
uint8_t count = 0;
uint8_t pins = 7;

void isr(void);

uint8_t  sine_wave[16] = {
0x80,0xb0,0xda,0xf5,0xff,0xf5,0xda,0xb0,
0x80,0x4f,0x25,0x0a,0x00,0x0a,0x25,0x4f
};

// Automatically retrieve TIM instance and channel associated to pin
// This is used to be compatible with all STM32 series automatically.
TIM_TypeDef *Instance = (TIM_TypeDef *)pinmap_peripheral(digitalPinToPinName(pin), PinMap_PWM);
uint32_t channel = STM_PIN_CHANNEL(pinmap_function(digitalPinToPinName(pin), PinMap_PWM));
// Instantiate HardwareTimer object. Thanks to 'new' instantiation, HardwareTimer is not destructed when setup() function is finished.
HardwareTimer *MyTim = new HardwareTimer(Instance);

void setup()
{
  MyTim->pause();
  MyTim->setPrescaleFactor(1);  // Timer PreScale Factor 1
  MyTim->setOverflow(PWM_OVERFLOW);  // 72000000 / PWM OVERFLOW = 40Khz
  MyTim->setMode(4, TIMER_OUTPUT_COMPARE);
  MyTim->setCaptureCompare(4, PWM_OVERFLOW);
  MyTim->attachInterrupt(4, isr);

  // Configure and start PWM
  MyTim->refresh();
  MyTim->resume();
  MyTim->setPWM(channel, pin, 4000, 50);
  pinMode(PC13, OUTPUT);  // LED out
  pinMode(PA9, OUTPUT);  // LED out
  digitalWrite(PA9, HIGH);
}


void loop()
{
  /* Nothing to do all is done by hardware. Even no interrupt required. */
  digitalWrite(PC13, HIGH);
  delay(1000);
  digitalWrite(PC13, LOW);
  delay(1000);
}

void isr(void) {
  // convert frequency to Pulse Width Modulation Duty Cycle Using DMA
  // center on PWM_OVERFLOW
  //uint16_t pDuty = (uint16_t)map(buffer[0],0,4095,0,PWM_OVERFLOW/2-1);
  //pwmWrite(PWM_OUT,PWM_OVERFLOW/2+pDuty);

  // alternate modulation #2 - louder but worse quality
  //uint16_t pDuty = (uint16_t)map(buffer[0],0,4095,0,PWM_OVERFLOW);
  //pwmWrite(PWM_OUT,pDuty-1);

  // alternate #3
  //pwmWrite(PWM_OUT,(((PWM_OVERFLOW-2) * buffer[0]/4096))+1);


  // sine wave test
  int16_t pDuty = sine_wave[count++]*100/128;
  MyTim->pause();
  MyTim->setPWM(channel, pin, 4000, pDuty);
  MyTim->refresh();
  MyTim->resume();
  if(count >= 15) 
    count = 0;
}