#define DAC_SW    48

#define DAC_LED0  46
#define DAC_LED1  50

int dac_select = 0;
bool dac_sw_pressed = false;

#define LP_OUT_CLK  7

//max 12
#define BITS    12

//max 150000
#define FILT_FREQ 150000

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

  //analog
  analogWriteResolution(BITS);

  //DAC
  pinMode(DAC_SW, INPUT);
  digitalWrite(DAC_SW, HIGH);  
  
  pinMode(DAC_LED0, OUTPUT);
  digitalWrite(DAC_LED0, HIGH);
  pinMode(DAC_LED1, OUTPUT);

  pinMode(DAC0, OUTPUT);
  pinMode(DAC1, OUTPUT);

  //PWM
  pinMode(LP_OUT_CLK, OUTPUT);

  //50%
  analogWrite(LP_OUT_CLK, pow(2, BITS) / 2);

  PWMC_ConfigureClocks(FILT_FREQ * PWM_MAX_DUTY_CYCLE, 0, VARIANT_MCK);
}

bool check_switch(int in, int led0, int led1, int * select, bool * pressed)
{
  if (digitalRead(in) == 0 && *pressed == false)
  {
    *pressed = true;
    *select = !(*select);

    digitalWrite(led0, *select == 0);
    digitalWrite(led1, *select == 1);

    return true;
  }
  
  if (digitalRead(in) == 1)
    *pressed = false;
    
  return false;
}


int64_t y = 0;
uint32_t next = 0;


//**************** Premenne ******************************

#define PERIOD  1000
int64_t a = 0;
//********************************************************


void loop() {
  check_switch(DAC_SW, DAC_LED0, DAC_LED1, &dac_select, &dac_sw_pressed);

  //fix period time to 100us (10kHz)
  while (next > micros());
  next = micros() + PERIOD;

//**************** Generator *****************************

  if ( a == 0 ) {
    a = 1;
    y = 4095;
  }else{
    a = 0;
    y = 0;
  }

//********************************************************
  
  //y += 2047;

  //clamp values
  if (y > 4095) y = 4095;
  if (y < 0) y = 0;


  analogWrite(DAC1, y);
}