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92 lines
2.7 KiB
C
92 lines
2.7 KiB
C
#include <avr/io.h>
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#include <avr/pgmspace.h>
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#include <avr/interrupt.h>
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#include <stdlib.h>
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#include "pt100.h"
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uint16_t adc_buffer[AVRG];
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volatile float ch_values[10];
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void adc_init(void){
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ADCA.CTRLB = ADC_FREERUN_bm;
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ADCA.REFCTRL = ADC_REFSEL_VCC_gc;
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ADCA.PRESCALER = ADC_PRESCALER_DIV512_gc;
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uint8_t CalibrationByteL;
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uint8_t CalibrationByteH;
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NVM_CMD = NVM_CMD_READ_CALIB_ROW_gc;
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CalibrationByteL = pgm_read_byte(offsetof(NVM_PROD_SIGNATURES_t, ADCACAL0));
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CalibrationByteH = pgm_read_byte(offsetof(NVM_PROD_SIGNATURES_t, ADCACAL1));
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NVM_CMD = NVM_CMD_NO_OPERATION_gc;
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ADCA.CALL = CalibrationByteL;
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ADCA.CALH = CalibrationByteH;
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ADCA.CTRLA = ADC_ENABLE_bm;
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ADCA.CH0.CTRL = ADC_CH_INPUTMODE_SINGLEENDED_gc;
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ADCA.CH0.MUXCTRL = ADC_CH_MUXPOS_PIN0_gc;
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}
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void dma_init(void){
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DMA.CTRL = DMA_ENABLE_bm;
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DMA.CH0.CTRLB = DMA_CH_TRNINTLVL_LO_gc;
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DMA.CH0.TRFCNT = AVRG * 2;
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DMA.CH0.CTRLA = DMA_CH_BURSTLEN_2BYTE_gc | DMA_CH_SINGLE_bm;
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DMA.CH0.TRIGSRC = DMA_CH_TRIGSRC_ADCA_CH0_gc;
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//repeat endless
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DMA.CH0.CTRLA |= DMA_CH_REPEAT_bm;
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DMA.CH0.REPCNT = 0;
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DMA.CH0.SRCADDR0 = ((uintptr_t)&ADCA.CH0.RES) & 0xFF;
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DMA.CH0.SRCADDR1 = (((uintptr_t)&ADCA.CH0.RES) >> 0x08) & 0xFF;
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DMA.CH0.SRCADDR2 = (((uintptr_t)&ADCA.CH0.RES) >> 0x0F) & 0xFF;
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DMA.CH0.DESTADDR0 = ((uintptr_t)adc_buffer) & 0xFF;
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DMA.CH0.DESTADDR1 = ((uintptr_t)adc_buffer >> 0x08) & 0xFF;
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DMA.CH0.DESTADDR2 = ((uintptr_t)adc_buffer >> 0x0F) & 0xFF;
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DMA.CH0.ADDRCTRL = DMA_CH_SRCRELOAD_BURST_gc | DMA_CH_DESTRELOAD_TRANSACTION_gc | DMA_CH_SRCDIR_INC_gc | DMA_CH_DESTDIR_INC_gc;
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DMA.CH0.CTRLA |= DMA_CH_ENABLE_bm;
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}
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float avrg(uint16_t * values, uint16_t length){
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uint64_t res = 0;
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//ommit first and last sample
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for(uint16_t i=1; i < length-1; i++){
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res += values[i];
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}
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return (float)(res)/(length-2);
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}
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ISR(DMA_CH0_vect){
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static uint8_t pin = 0;
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DMA.INTFLAGS |= DMA_CH0TRNIF_bm; // clear flag
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DMA.CH0.TRIGSRC = DMA_CH_TRIGSRC_OFF_gc;
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ADCA.CTRLB = 0; // stop ADC
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uint8_t old_pin = pin;
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pin=(pin+1)%10;
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ADCA.CH0.MUXCTRL = pin << ADC_CH_MUXPOS_gp; // give MUX time to switch during calculation
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float temp = avrg(adc_buffer, AVRG);
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temp = temp - ADC_0V_COUNT;
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temp = (temp)/ (4096-ADC_0V_COUNT) * ADC_MAX_VOLT;
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if(old_pin <= 8){ /* pt100 temperature channels */
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temp = (temp * REF_OHMS)/(SUPPLY_VOLTS - temp);
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temp = (temp-100)/0.3927; //pt100 formula
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ch_values[old_pin] = temp;
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}
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if(old_pin == 9){ /* 24V supply voltage measurement */
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// resistor devider 33k and 1k
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ch_values[old_pin] = temp * 34;
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}
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DMA.CH0.TRIGSRC = DMA_CH_TRIGSRC_ADCA_CH0_gc;
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ADCA.CTRLB = ADC_FREERUN_bm; // start ADC again
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}
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