#include <Wire.h>
#include <Adafruit_MCP4728.h>

#define BAUDRATE  115200

#define I2C_SDA   15
#define I2C_SCL   16
#define I2C_FREQ  400000

#define DAC_MAX   4095
#define DAC_MIN   0
#define VREF_mV   2048

#define VREF_CONF_IN_USE MCP4728_VREF_INTERNAL

#define PIN_BTN   40

Adafruit_MCP4728 mcp;

static uint16_t value_mV = VREF_mV;

bool button_state_old = false;
bool button_state_now = false;

uint16_t voltage(uint16_t mV)
{
  return map(mV, 0, VREF_mV, DAC_MIN, DAC_MAX);
}

void setup() 
{
  Serial.begin(BAUDRATE);
  delay(1000);
  Serial.print("\n\rMCP4728 DAC Test");

  Wire.begin(I2C_SDA, I2C_SCL);
  Wire.setClock(I2C_FREQ);

  pinMode(PIN_BTN, INPUT);

  Serial.print("\n\rInitialisiere MCP4728...");
  uint8_t attempts = 0;
  while (!mcp.begin()) 
  {
    if(attempts > 20)
    {
      Serial.print("\n\rError: Es konnte nach 20 Versuchen kein IC gefunden werden. Überprüfe die Verkabelung und starte den ESP neu!");
      for(;;);
    }
    Serial.print(".");
    delay(100);
    attempts++;
  }
  Serial.print("\n\rErfolgreich verbunden!");

  mcp.setChannelValue(MCP4728_CHANNEL_A, 4095, VREF_CONF_IN_USE);
  Serial.print("\n\rDAC-Kanal A auf 0 gesetzt");
  delay(1000);
}


void loop() 
{
  button_state_now = digitalRead(PIN_BTN);
  if (button_state_now != button_state_old) 
  {
    delay(10); // debounce delay
    button_state_now = digitalRead(PIN_BTN);
    if (button_state_now != button_state_old) 
    {
      button_state_old = button_state_now;
      if (button_state_now == HIGH) 
      {
        if(value_mV < 2000) value_mV += (1000/12);
        if(value_mV >= 2000) value_mV = 0;

        if (mcp.setChannelValue(MCP4728_CHANNEL_A, voltage(value_mV), VREF_CONF_IN_USE)) Serial.printf("DAC A = %u -> mV: %u\r\n", voltage(value_mV), value_mV);
        else Serial.println("Error: Neuer MCP4728 Wert konnte nicht gesetzt werden!");
      }
    }
  }
}