46 lines
1.2 KiB
C++
46 lines
1.2 KiB
C++
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#include "ADC.hpp"
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#define NUM_PINS 4
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const uint8_t adc_pins[] = {0, 1, 4, 5}; // A0, A1, A4, A5
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volatile uint16_t adc_results[NUM_PINS];
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volatile uint8_t current_channel_index = 0;
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void setupADC() {
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// 1. Set Reference to AVCC (5V)
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// REFS0 = 1, REFS1 = 0
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ADMUX = (1 << REFS0);
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// 2. Set ADC Prescaler to 128 (16MHz / 128 = 125KHz)
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// Good balance of speed and accuracy.
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// Bits: ADPS2, ADPS1, ADPS0
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ADCSRA |= (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0);
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// 3. Enable ADC and Enable ADC Interrupt
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ADCSRA |= (1 << ADEN) | (1 << ADIE);
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// 4. Set initial channel to the first pin in our list
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ADMUX = (ADMUX & 0xF0) | (adc_pins[0] & 0x0F);
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// 5. Start the first conversion!
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ADCSRA |= (1 << ADSC);
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}
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ISR(ADC_vect) {
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// 1. Read the result (must read ADCL first, then ADCH, or just use ADC word)
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adc_results[current_channel_index] = ADC;
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// 2. Increment to next channel
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current_channel_index++;
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if (current_channel_index >= NUM_PINS) {
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current_channel_index = 0;
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}
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// 3. Switch MUX to next channel
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// Clear bottom 4 bits of ADMUX, then OR in the new pin number
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ADMUX = (ADMUX & 0xF0) | (adc_pins[current_channel_index] & 0x0F);
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// 4. Start next conversion
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ADCSRA |= (1 << ADSC);
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}
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