#include <avr/io.h>
#include <avr/pgmspace.h>
#include <avr/interrupt.h>
#include <stdlib.h>
#include "pt100.h"

uint16_t adc_buffer[AVRG];
volatile float ch_values[10];

void adc_init(void){
    ADCA.CTRLB = ADC_FREERUN_bm;
    ADCA.REFCTRL = ADC_REFSEL_VCC_gc;
    ADCA.PRESCALER = ADC_PRESCALER_DIV512_gc;

    uint8_t CalibrationByteL;
    uint8_t CalibrationByteH;
    NVM_CMD = NVM_CMD_READ_CALIB_ROW_gc;
    CalibrationByteL = pgm_read_byte(offsetof(NVM_PROD_SIGNATURES_t, ADCACAL0));
    CalibrationByteH = pgm_read_byte(offsetof(NVM_PROD_SIGNATURES_t, ADCACAL1));
    NVM_CMD = NVM_CMD_NO_OPERATION_gc;
    ADCA.CALL = CalibrationByteL;
    ADCA.CALH = CalibrationByteH;

    ADCA.CTRLA = ADC_ENABLE_bm;

    ADCA.CH0.CTRL = ADC_CH_INPUTMODE_SINGLEENDED_gc;
    ADCA.CH0.MUXCTRL = ADC_CH_MUXPOS_PIN0_gc;
}

void dma_init(void){
    DMA.CTRL = DMA_ENABLE_bm;

    DMA.CH0.CTRLB = DMA_CH_TRNINTLVL_LO_gc;

    DMA.CH0.TRFCNT = AVRG * 2;
    DMA.CH0.CTRLA = DMA_CH_BURSTLEN_2BYTE_gc | DMA_CH_SINGLE_bm;
    DMA.CH0.TRIGSRC = DMA_CH_TRIGSRC_ADCA_CH0_gc;

    //repeat endless
    DMA.CH0.CTRLA |= DMA_CH_REPEAT_bm;
    DMA.CH0.REPCNT = 0;

    DMA.CH0.SRCADDR0 = ((uintptr_t)&ADCA.CH0.RES) & 0xFF;
    DMA.CH0.SRCADDR1 = (((uintptr_t)&ADCA.CH0.RES) >> 0x08) & 0xFF;
    DMA.CH0.SRCADDR2 = (((uintptr_t)&ADCA.CH0.RES) >> 0x0F) & 0xFF;

    DMA.CH0.DESTADDR0 = ((uintptr_t)adc_buffer) & 0xFF;
    DMA.CH0.DESTADDR1 = ((uintptr_t)adc_buffer >> 0x08) & 0xFF;
    DMA.CH0.DESTADDR2 = ((uintptr_t)adc_buffer >> 0x0F) & 0xFF;

    DMA.CH0.ADDRCTRL = DMA_CH_SRCRELOAD_BURST_gc | DMA_CH_DESTRELOAD_TRANSACTION_gc | DMA_CH_SRCDIR_INC_gc | DMA_CH_DESTDIR_INC_gc;

    DMA.CH0.CTRLA |= DMA_CH_ENABLE_bm;
}

float avrg(uint16_t * values, uint16_t length){
    uint64_t res = 0;
    //ommit first and last sample
    for(uint16_t i=1; i < length-1; i++){
        res += values[i];
    }
    return (float)(res)/(length-2);
}

ISR(DMA_CH0_vect){
    static uint8_t pin = 0;

    DMA.INTFLAGS |= DMA_CH0TRNIF_bm; // clear flag
    DMA.CH0.TRIGSRC = DMA_CH_TRIGSRC_OFF_gc;
    ADCA.CTRLB = 0; // stop ADC

    uint8_t old_pin = pin;
    pin=(pin+1)%10;
    ADCA.CH0.MUXCTRL = pin << ADC_CH_MUXPOS_gp; // give MUX time to switch during calculation
    float temp = avrg(adc_buffer, AVRG);
    temp = temp - ADC_0V_COUNT;
    temp = (temp)/ (4096-ADC_0V_COUNT) * ADC_MAX_VOLT;

    if(old_pin <= 8){ /* pt100 temperature channels */
        temp = (temp * REF_OHMS)/(SUPPLY_VOLTS - temp);
        temp = (temp-100)/0.3927; //pt100 formula
        ch_values[old_pin] = temp;
    }
    if(old_pin == 9){ /* 24V supply voltage measurement */
        // resistor devider 33k and 1k
        ch_values[old_pin] = temp * 34;
    }

    DMA.CH0.TRIGSRC = DMA_CH_TRIGSRC_ADCA_CH0_gc;
    ADCA.CTRLB = ADC_FREERUN_bm; // start ADC again
}