pentabug/firmware/lib/listen.c
2013-12-09 15:05:44 +01:00

67 lines
976 B
C

#include <pentabug/listen.h>
#include <avr/io.h>
#include <pentabug/hal.h>
#include <pentabug/lifecycle.h>
void listen_init(void) {
ADCSRA |= (1 << ADEN);
}
void listen_stop(void) {
ADCSRA &= ~(1 << ADEN);
}
uint16_t listen_measure(void) {
// save previous state
uint8_t prev_state = PINC & (1 << 0);
// set to ground for discharge
DDRC |= 1 << 0;
PORTC &= ~(1 << 0);
// wait for discharge
wait_ms(1);
// set direction to input for measurement
DDRC &= ~(1 << 0);
// collect some sound waves
wait_ms(1);
// start measurement
// TODO: why can't i move this to the initialization?
ADMUX = (1 << REFS0) | (1 << ADLAR);
ADCSRA |= (1 << ADPS2) | (1 << ADPS1);
ADMUX = (ADMUX & ~(0x1F)) | 0;
ADCSRA |= (1 << ADSC);
// wait for measurement to finish
while (ADCSRA & (1 << ADSC)) test_stop_app();
uint16_t res = ADCL;
res |= ADCH << 8;
// restore state
if(prev_state) {
PORTC |= 1 << 0;
}
DDRC |= 1 << 0;
// done
return res;
}