37 lines
1.6 KiB
C
37 lines
1.6 KiB
C
#include "header.h"
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// 24.2 : The ADC generates a 10-bit result which is presented in the ADC Data Registers, ADCH and ADCL
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void adc_init(uint8_t prescaler_value) {
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ADMUX = (1 << REFS0); // Table 24-3 : set voltage reference, AVCC with external capacitor at AREF pin
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ADMUX |= (1 << ADLAR); // 24.9.1 : result is left adjusted, meaning the first 8 bits values are readable in ADCH, (24.9.3.2 : ADC data register is not updated util ADCH is read)
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ADCSRA = (1 << ADEN); // 24.9.2 : enable ADC
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ADCSRA |= (1 << ADATE); // 24.9.2 : enable Auto Trigger -> it will start a conversion on the selected channel in ADMUX when the selected source (in ADCSRB) is triggered
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ADCSRA |= (1 << ADIE); // 24.9.2 : enable ADC Interrupt
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ADCSRA |= ADC_PRESCALE_SET(prescaler_value); // Table 24-5 : prescaler ADC
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ADCSRB = ADC_TRIGGER_TIMER_1_COMPARE_B; // Table 24-6 : ADC Auto Trigger Source
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ADMUX = (ADMUX & 0b11110000) | (adc_channel & 0b1111); // Table 24-4 : Select ADC channel 0
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}
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void adc_print_hex(uint8_t value) {
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char buffer[3] = {0};
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int_to_hex_string(value, buffer, 2);
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uart_printstr(buffer);
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}
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ISR(ADC_vect) { // Table 12-6 : interrupt vector for ADC Conversion Complete
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uint8_t value = ADCH; // 24.9.3.2 : read ADCH 8 bits precision
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adc_print_hex(value);
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// loop through channel
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adc_channel = (adc_channel + 1) % 3; // loop through channels
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ADMUX = (ADMUX & 0b11110000) | (adc_channel & 0b1111); // Table 24-4 : Select next ADC channel
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if (adc_channel != 0) {
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uart_printstr(", ");
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ADCSRA |= (1 << ADSC); // 24.9.2 : start next conversion
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} else {
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uart_printstr("\r\n");
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}
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}
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