osd-contiki/cpu/avr/hw_timer.c
Ralf Schlatterbeck 5991c3e3db Initial implementation of avr hardware timer
Mainly for PWM use for now.
With example to set the LED to different brightness via COAP.
We switch the LED with 50 kHz (20µs) in this example.
2014-06-22 13:32:05 +02:00

104 lines
3.2 KiB
C

/*
* Copyright (c) 2014, Ralf Schlatterbeck Open Source Consulting
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the Contiki operating system.
*/
/**
* \addgroup hardware timer
*
* @{
*/
/**
* \file
* Header file for hardware timer of AVR microcontrollers
* \author
* Ralf Schlatterbeck <rsc@runtux.com>
*/
#include <avr/pgmspace.h>
#include "contiki.h"
#include "rtimer-arch.h"
#include "hw_timer.h"
#ifndef PLAT_TIMER
#define PLAT_TIMER 0xFF /* invalid timer for comparison */
#endif
int8_t hwtimer_ini (uint8_t timer, uint8_t wgm, uint8_t clock, uint16_t maxt)
{
int8_t i;
HWT_CHECK_TIMER (timer);
if (wgm > HWT_WGM_MASK || wgm == HWT_WGM_RESERVED) {
return HWT_ERR_INVALID_WGM;
}
if (clock > HWT_CLOCK_MASK) {
return HWT_ERR_INVALID_CLOCK;
}
/* Turn off clock, no need to disable interrupt */
*HWT_TCCRB (timer) &= ~HWT_CLOCK_MASK;
*HWT_TCCRA (timer) &= ~(HWT_WGM_MASK_LOW << HWT_WGM_SHIFT_LOW);
*HWT_TCCRA (timer) |= ((wgm & HWT_WGM_MASK_LOW) << HWT_WGM_SHIFT_LOW);
*HWT_TCCRB (timer) &= ~(HWT_WGM_MASK_HIGH << HWT_WGM_SHIFT_HIGH);
*HWT_TCCRB (timer) |= ((wgm & HWT_WGM_MASK_HIGH) << HWT_WGM_SHIFT_HIGH);
for (i=0; i<3; i++) {
HWT_SET_COM (timer, i, HWT_COM_NORMAL);
}
if ( wgm == HWT_WGM_PWM_PHASE_FRQ_ICR
|| wgm == HWT_WGM_PWM_PHASE_ICR
|| wgm == HWT_WGM_CTC_ICR
|| wgm == HWT_WGM_PWM_FAST_ICR
)
{
*HWT_ICR (timer) = maxt;
}
if ( wgm == HWT_WGM_CTC_OCRA
|| wgm == HWT_WGM_PWM_PHASE_FRQ_OCRA
|| wgm == HWT_WGM_PWM_PHASE_OCRA
|| wgm == HWT_WGM_PWM_FAST_OCRA
)
{
*HWT_OCRA (timer) = maxt;
}
/* Set clock, finally */
*HWT_TCCRB (timer) |= clock;
return 0;
}
/*
* ex:ts=8:et:sw=2
*/
/** @} */