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#include <avr/interrupt.h>
#include <avr/io.h>
volatile unsigned short adc_value = 0x5555;
volatile unsigned char complete = 1;
volatile unsigned char in_loop = 0;
void init(void) {
// ADMUX: channel 6 (ADC2-ADC3), ADLAR = 0, REFS = 6 (2.56V)
ADMUX = 0x96;
// ADEN = 1, ADIE = 0, ADPS = 5 CKx32 = 125kHz
ADCSRA = 0x85;
// BIN = 1
ADCSRB = 0x80;
}
int main(void) {
init();
do {
in_loop = 1;
switch(complete) {
case 0:
// wait until conversion complete, then get adc value
if((ADCSRA & _BV(ADSC)) == 0) {
// read ADC value
adc_value = ADCL | (ADCH << 8);
complete = 1;
}
break;
case 1:
// conversion complete, idle
break;
case 2:
// start conversion, channel 6
ADMUX = 0x96;
// set bipolar mode
ADCSRB = 0x80;
// start conversion
ADCSRA |= _BV(ADSC);
complete = 0;
break;
case 3:
// start conversion, channel 6
ADMUX = 0x96;
// set unipolar mode
ADCSRB = 0x00;
// start conversion
ADCSRA |= _BV(ADSC);
complete = 0;
break;
case 4:
// start conversion, channel 6
ADMUX = 0x96;
// set unipolar mode with IPR
ADCSRB = 0x20;
// start conversion
ADCSRA |= _BV(ADSC);
complete = 0;
break;
}
} while(1); // do forever
}
// EOF
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