27 lines
1.4 KiB
C
27 lines
1.4 KiB
C
#include "header.h"
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// Table 14-6. Port C Pins Alternate Functions
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// - PC0 -> ADC0 (ADC Input Channel 0)
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// -> PCINT8 (Pin Change Interrupt 8)
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//
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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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//
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// START A CONVERSTION in single conversion mode :
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// - disabling the Power Reduction ADC bit, PRADC
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// - writing a logical one to the ADC Start Conversion bit, ADSC
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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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ADCSRA = (1 << ADEN); // 24.9.2 : enable ADC
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ADCSRA |= ADC_PRESCALE_SET(prescaler_value); // Table 24-5 : prescaler ADC
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}
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uint16_t adc_read(uint8_t channel) {
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CLEAR(PRR, PRADC); // 24.3 : ensure power reduction is disabled for ADC, (10.11.3 : PRR – Power Reduction Register)
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ADMUX = (ADMUX & 0b11110000) | (channel & 0b1111); // Table 24-4 : Select ADC channel, (Table 14-6 : alternate function for RV1 on PC0 -> ADC0)
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ADMUX |= (1 << ADLAR); // 24.9.1 : enable left adjust result
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ADCSRA |= (1 << ADSC); // 24.9.2 : Start conversion, ADSC: ADC Start Conversion
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while (ADCSRA & (1 << ADSC)); // Wait for completion
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return ADCH; // 24.9.3 : ADC updated only when ADCH is read, not ADCL, so for 8 bits precision uses left adjust result to only read ADCH
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}
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