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/*
* Pneumatic pressure controller.
* Sensor input.
*
* Copyright (C) 2008 Michael Buesch <mb@bu3sch.de>
*
* This program 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.
*
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "sensor.h"
#include "util.h"
#include <avr/io.h>
#include <avr/interrupt.h>
/*** The sensor enable signal ***/
#define SENSOR_ENABLE_DDR DDRC
#define SENSOR_ENABLE_PORT PORTC
#define SENSOR_ENABLE_BIT 1
static inline void sensor_enable(void)
{
SENSOR_ENABLE_PORT |= (1 << SENSOR_ENABLE_BIT);
}
static inline void sensor_disable(void)
{
SENSOR_ENABLE_PORT &= ~(1 << SENSOR_ENABLE_BIT);
}
ISR(ADC_vect)
{
uint16_t val;
val = ADC;
sensor_disable();
//TODO process value
sensor_result(val);
}
static inline void adc_trigger(bool with_irq)
{
/* Set the multiplexer to ADC-0, AVcc Ref. */
ADMUX = (1 << REFS0);
/* Start ADC with a prescaler of 128. That's a ADC freq
* of 125kHz on a 16MHz crystal. */
ADCSRA = (1 << ADEN) | (1 << ADSC) |
(1 << ADPS0) | (1 << ADPS1) | (1 << ADPS2) |
(with_irq ? (1 << ADIE) : 0);
}
void sensor_trigger_read(void)
{
/* Enable the sensor and wait a dwell time for the
* sensor to stabilize. */
sensor_enable();
udelay(500);
/* Finally trigger the ADC conversion. */
adc_trigger(1);
}
void sensor_init(void)
{
SENSOR_ENABLE_DDR |= (1 << SENSOR_ENABLE_BIT);
sensor_disable();
/* Discard the first ADC result. */
adc_trigger(0);
while (ADCSRA & (1 << ADSC))
mb();
}
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