ADC im SAMD21

void adc_init() {

/*  Temperature Sensor Enable bit          VREF.TSEN

   Bandgap Reference Voltage Generator       VREF.BGOUTEN */

  REG_SYSCTRL_VREF = 6; // BGOUTEN | TSEN

  REG_ADC_CTRLA = 1; // reset ADC

  while(REG_ADC_STATUS);

  #define REFCTRL_INT1V  0x00

  #define REFCTRL_INTVCC0  0x01

  #define REFCTRL_INTVCC1  0x02

  #define REFCTRL_VREFA  0x03

  #define REFCTRL_VREFB  0x04

  REG_ADC_REFCTRL = REFCTRL_INTVCC1;    

  while(REG_ADC_STATUS);

  #define AVGCTRL_AVG1  0x0

  #define AVGCTRL_AVG8  0x3 || 0x03 << 4;

  #define AVGCTRL_AVG128  0x7 || 0x04 << 4;

  #define AVGCTRL_AVG1024  0xA || 0x04 << 4;

  REG_ADC_AVGCTRL = AVGCTRL_AVG1024;

  while(REG_ADC_STATUS);

  REG_ADC_SAMPCTRL = 0;  // Sample_Time = 2 * (val + 1) / (F_ADC)

  while(REG_ADC_STATUS);

  REG_ADC_INTENSET = 1; // enable RESRDY (result ready interrupt)

  while(REG_ADC_STATUS);

  #define PRE_DIV4    0 << 8

  #define PRE_DIV64    4 << 8

  #define PRE_DIV512    7 << 8

  #define RESSEL12BIT    0 << 4

  #define RESSEL16BITAVG  1 << 4

  #define RESSEL10BIT    2 << 4

  #define RESSEL8BIT    3 << 4

  #define CORREN      1 << 3  // Digital Correction Logic Enabled

  #define FREERUN      1 << 2

  #define LEFTADJ      1 << 1  //  Left-Adjusted Result

  #define DIFFMODE    1 << 0

  REG_ADC_CTRLB = RESSEL12;

  while(REG_ADC_STATUS);

}

ui8 adc_get(ui16*adc_val, ui32 inputctrl) {

  REG_ADC_INPUTCTRL = inputctrl;

  while(REG_ADC_STATUS);  

  REG_ADC_CTRLA = 2; // enable ADC

  while(REG_ADC_STATUS);

  REG_ADC_SWTRIG = 2; // start conversion

  while(REG_ADC_STATUS);

  wait(1000);

  if(REG_ADC_INTFLAG & 1) {

    REG_ADC_INTFLAG = 0xf;

    *adc_val = REG_ADC_RESULT;

    state = init1;

    result = TRUE;

  }

  return 0;

}