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/*
* Copyright © 2012 Robert D. Garbee <robert@gag.com>
*
* 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; version 2 of the License.
*
* 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, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*/
#include "ao.h"
#include "ao_pwmin.h"
/*
* This code implements a PWM input using ICP3.
*
* The initial use is to measure wind speed in the ULA/Ball summer intern
* project payload developed at Challenger Middle School.
*/
volatile __data uint16_t ao_tick3_count;
static void
ao_pwmin_display(void) __reentrant
{
uint8_t lo = TCNT1L;
uint8_t hi = TCNT1H;
uint16_t value = (hi <<8) | lo;
uint8_t lo3 = TCNT3L;
uint8_t hi3 = TCNT3H;
uint16_t value3 = (hi3 <<8) | lo3;
/* now display the value we read */
printf("timer 1: %5u %2x %2x\n", value, hi, lo);
printf("timer 3: %5u %2x %2x\n", value3, hi3, lo3);
}
ISR(TIMER3_COMPA_vect)
{
++ao_tick3_count;
}
__code struct ao_cmds ao_pwmin_cmds[] = {
{ ao_pwmin_display, "p\0PWM input" },
{ 0, NULL },
};
void
ao_pwmin_init(void)
{
/* do hardware setup here */
TCCR3A = ((0 << WGM31) | /* normal mode, OCR3A */
(0 << WGM30)); /* normal mode, OCR3A */
TCCR3B = ((0 << ICNC3) | /* no input capture noise canceler */
(0 << ICES3) | /* input capture on falling edge (don't care) */
(0 << WGM33) | /* normal mode, OCR3A */
(0 << WGM32) | /* normal mode, OCR3A */
(4 << CS30)); /* clk/256 from prescaler */
OCR3A = 1250; /* 8MHz clock */
TIMSK3 = (1 << OCIE3A); /* Interrupt on compare match */
/* set the spike filter bit in the TCCR3B register */
ao_cmd_register(&ao_pwmin_cmds[0]);
}
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