contiki/cpu/cc2430/dev/clock.c

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/*
* Copyright (c) 2009, Swedish Institute of Computer Science.
* 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.
*/
/**
* \file
* Implementation of the clock functions for the cc243x
* \author
* Zach Shelby (zach@sensinode.com) - original
* George Oikonomou - <oikonomou@users.sourceforge.net>
*/
#include "sys/clock.h"
#include "sys/etimer.h"
#include "cc2430_sfr.h"
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#include "sys/energest.h"
/* Sleep timer runs on the 32k RC osc. */
/* One clock tick is 7.8 ms */
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#define TICK_VAL (32768/128) /* 256 */
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/*---------------------------------------------------------------------------*/
#if CLOCK_CONF_STACK_FRIENDLY
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volatile __bit sleep_flag;
#else
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#endif
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/*---------------------------------------------------------------------------*/
/* Used in sleep timer interrupt for calculating the next interrupt time */
static unsigned long timer_value;
static volatile __data clock_time_t count = 0; /* Uptime in ticks */
static volatile __data clock_time_t seconds = 0; /* Uptime in secs */
/*---------------------------------------------------------------------------*/
/**
* One delay is about 0.6 us, so this function delays for len * 0.6 us
*/
void
clock_delay(unsigned int len)
{
unsigned int i;
for(i = 0; i< len; i++) {
__asm
nop
__endasm;
}
}
/*---------------------------------------------------------------------------*/
/**
* Wait for a multiple of ~8 ms (a tick)
*/
void
clock_wait(int i)
{
clock_time_t start;
start = clock_time();
while(clock_time() - start < (clock_time_t)i);
}
/*---------------------------------------------------------------------------*/
CCIF clock_time_t
clock_time(void)
{
return count;
}
/*---------------------------------------------------------------------------*/
CCIF unsigned long
clock_seconds(void)
{
return seconds;
}
/*---------------------------------------------------------------------------*/
void
clock_init(void)
{
CLKCON = OSC32K | TICKSPD2 | TICKSPD1; /* tickspeed 500 kHz for timers[1-4] */
/* Initialize tick value */
timer_value = ST0; /* ST low bits [7:0] */
timer_value += ((unsigned long int) ST1) << 8; /* middle bits [15:8] */
timer_value += ((unsigned long int) ST2) << 16; /* high bits [23:16] */
timer_value += TICK_VAL; /* Init value 256 */
ST2 = (unsigned char) (timer_value >> 16);
ST1 = (unsigned char) (timer_value >> 8);
ST0 = (unsigned char) timer_value;
IEN0_STIE = 1; /* IEN0.STIE acknowledge Sleep Timer Interrupt */
}
/*---------------------------------------------------------------------------*/
void
clock_ISR(void) __interrupt(ST_VECTOR)
{
DISABLE_INTERRUPTS();
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ENERGEST_ON(ENERGEST_TYPE_IRQ);
/*
* If the Sleep timer throws an interrupt while we are powering down to
* PM1, we need to abort the power down. Clear SLEEP.MODE, this will signal
* main() to abort the PM1 transition
*/
SLEEP &= 0xFC;
/*
* Read value of the ST0:ST1:ST2, add TICK_VAL and write it back.
* Next interrupt occurs after the current time + TICK_VAL
*/
timer_value = ST0;
timer_value += ((unsigned long int) ST1) << 8;
timer_value += ((unsigned long int) ST2) << 16;
timer_value += TICK_VAL;
ST2 = (unsigned char) (timer_value >> 16);
ST1 = (unsigned char) (timer_value >> 8);
ST0 = (unsigned char) timer_value;
++count;
/* Make sure the CLOCK_CONF_SECOND is a power of two, to ensure
that the modulo operation below becomes a logical and and not
an expensive divide. Algorithm from Wikipedia:
http://en.wikipedia.org/wiki/Power_of_two */
#if (CLOCK_CONF_SECOND & (CLOCK_CONF_SECOND - 1)) != 0
#error CLOCK_CONF_SECOND must be a power of two (i.e., 1, 2, 4, 8, 16, 32, 64, ...).
#error Change CLOCK_CONF_SECOND in contiki-conf.h.
#endif
if(count % CLOCK_CONF_SECOND == 0) {
++seconds;
}
#if CLOCK_CONF_STACK_FRIENDLY
sleep_flag = 1;
#else
if(etimer_pending()
&& (etimer_next_expiration_time() - count - 1) > MAX_TICKS) {
etimer_request_poll();
}
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#endif
IRCON_STIF = 0;
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ENERGEST_OFF(ENERGEST_TYPE_IRQ);
ENABLE_INTERRUPTS();
}
/*---------------------------------------------------------------------------*/