// Super helpful thread:
// https://forum.arduino.cc/t/metro-m4-express-atsamd51-pwm-frequency-and-resolution/566491
#include "SAMDTimerInterrupt.h"

void setup() {
  Serial.begin(115200);

  SAMDTimer ITimer0(TIMER_TC3);

  if (ITimer0.attachInterruptInterval(1000, TimerHandler0))
    Serial.println("Starting ITimer0, millis()=" + String(millis()));
  else
    Serial.println("Failed to start ITimer0");

    // Set up the generic clock (GCLK7) to clock timer TCC0 
  GCLK->GENCTRL[7].reg = GCLK_GENCTRL_DIV(1) |       // Divide the 48MHz clock source by divisor 1: 48MHz/1 = 48MHz
                         GCLK_GENCTRL_IDC |          // Set the duty cycle to 50/50 HIGH/LOW
                         GCLK_GENCTRL_GENEN |        // Enable GCLK7
                         //GCLK_GENCTRL_SRC_DFLL;      // Select 48MHz DFLL clock source
                         //GCLK_GENCTRL_SRC_DPLL1;     // Select 100MHz DPLL clock source
                         GCLK_GENCTRL_SRC_DPLL0;     // Select 120MHz DPLL clock source
  while (GCLK->SYNCBUSY.bit.GENCTRL7);               // Wait for synchronization  

  GCLK->PCHCTRL[25].reg = GCLK_PCHCTRL_CHEN |        // Enable the TCC0 peripheral channel
                          GCLK_PCHCTRL_GEN_GCLK7;    // Connect generic clock 7 to TCC0

  // Enable the peripheral multiplexer on pin D7
  PORT->Group[g_APinDescription[7].ulPort].PINCFG[g_APinDescription[7].ulPin].bit.PMUXEN = 1;
  PORT->Group[g_APinDescription[9].ulPort].PINCFG[g_APinDescription[9].ulPin].bit.PMUXEN = 1;

  // Set the D7 (PORT_PB12) peripheral multiplexer to peripheral (even port number) E(6): TCC0, Channel 0
  PORT->Group[g_APinDescription[7].ulPort].PMUX[g_APinDescription[7].ulPin >> 1].reg |= PORT_PMUX_PMUXE(6);
  PORT->Group[g_APinDescription[9].ulPort].PMUX[g_APinDescription[9].ulPin >> 1].reg |= PORT_PMUX_PMUXO(6);
  
  TCC0->CTRLA.reg = TC_CTRLA_PRESCALER_DIV1 |        // Set prescaler to 1, 120MHz/1 = 120MHz
                    TC_CTRLA_PRESCSYNC_PRESC;        // Set the reset/reload to trigger on prescaler clock                 

  TCC0->WAVE.reg = TC_WAVE_WAVEGEN_NPWM;             // Set-up TCC0 timer for Normal (single slope) PWM mode (NPWM)
  while (TCC0->SYNCBUSY.bit.WAVE)                    // Wait for synchronization

  TCC0->PER.reg = 5999;                            // Set-up the PER (period) register 1000Hz PWM
  while (TCC0->SYNCBUSY.bit.PER);                    // Wait for synchronization
  
  TCC0->CC[0].reg = 2999;                           // Set-up the CC (counter compare), channel 0 register for 50% duty-cycle
  while (TCC0->SYNCBUSY.bit.CC0);                    // Wait for synchronization

  TCC0->CC[1].reg = 2999;
  while (TCC0->SYNCBUSY.bit.CC1);
  
  TCC0->CTRLA.bit.ENABLE = 1;                        // Enable timer TCC0
  while (TCC0->SYNCBUSY.bit.ENABLE);                 // Wait for synchronization
}

float phinc;  // phase increment
float ph;     // phase accumulator
unsigned long ampl;   // amplitude scaling

void TimerHandler0(void) 
{
  float s, c;
  
  ph += phinc;

  s = sin(ph);
  c = cos(ph);
  
  TCC0->CCBUF[0].reg = ampl * s + 3000;
  TCC0->CCBUF[1].reg = ampl * c + 3000;

  analogWrite(A0, s*2047 + 2048);
  analogWrite(A1, c*2047 + 2048);
}

uint16_t value;
uint16_t oldvalue;

void loop()
{
   
  value = analogRead(A4);

  if (value < 10)
    value = 10;
    
  phinc = value * (M_PI / 16384);

  ampl = 1000;

  //if ((value > oldvalue+5) || (value < oldvalue-5))
  //  Serial.printf("%d value\n", value);

  oldvalue = value;
}