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/*
atmega644_adc_test.c
Copyright 2008, 2009 Michel Pollet <buserror@gmail.com>
This file is part of simavr.
simavr is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
simavr is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with simavr. If not, see <http://www.gnu.org/licenses/>.
*/
#include <avr/io.h>
#include <stdio.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include <avr/sleep.h>
/*
* This demonstrate how to use the avr_mcu_section.h file
* The macro adds a section to the ELF file with useful
* information for the simulator
*/
#include "avr_mcu_section.h"
AVR_MCU(F_CPU, "atmega644");
AVR_MCU_VOLTAGES(3300, 3300, 3300); // 3.3V VCC, AVCC, VREF
static int uart_putchar(char c, FILE *stream) {
if (c == '\n')
uart_putchar('\r', stream);
loop_until_bit_is_set(UCSR0A, UDRE0);
UDR0 = c;
return 0;
}
static FILE mystdout = FDEV_SETUP_STREAM(uart_putchar, NULL,
_FDEV_SETUP_WRITE);
volatile uint16_t adc_val[8];
ISR(ADC_vect)
{
uint8_t mux = ADMUX, l = ADCL, h = ADCH;
uint8_t i = mux & 7;
adc_val[i] = l | (h << 8);
i = (i + 1) & 7;
ADMUX = (mux & 0xF0) | i;
if (i)
ADCSRA |= (1 << ADSC); // restart one now on the new channel
}
void adc_init()
{
// set ADC
ADMUX = (1 << REFS0); // use internal AVCC (3.3)
// enable ADC, start a conversion, with the interrupt
// and with a /128 integration clock
ADCSRA = (1 << ADEN) | (1 << ADSC) | (1 << ADIE) | 0x5;
// doesn't do anything in simavr for now
DIDR0 = 3; // disable digital on these 2 pins ADC0 and ADC1
}
int main(void)
{
stdout = &mystdout;
sei();
printf("Read 8 ADC channels to test interrupts\n");
adc_init();
/*
* The interupt reads all 8 ADCs then stop...
* so this loop will eventually exits
*/
while (ADCSRA & (1 << ADSC))
sleep_cpu();
printf("All done. Now reading the 1.1V value in pooling mode\n");
ADCSRA &= ~(1 << ADIE); // remove interrupt
// 1.1 reference voltage, left aligned
ADMUX = (ADMUX & ~0x1f)| (0 << ADLAR) | 0x1e;
ADCSRA |= (1 << ADSC) ; // start conversion
while (ADCSRA & (1 << ADSC))
;
uint16_t v = ADCL | (ADCH << 8);
uint16_t volts = (v * 3300L) >> 10; // div 1024
printf("Read ADC value %04x = %d mvolts -- ought to be 1098\n", v, volts);
ADCSRA &= ~(1 << ADEN); // disable ADC...
cli();
sleep_cpu();
}
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