nes-proj/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.
*
* $Id: clock.c,v 1.1 2009/09/08 20:07:35 zdshelby Exp $
*/
/**
* \file
* Implementation of the clock functions for the 8051 CPU
* \author
* Zach Shelby (zach@sensinode.com)
*/
/**
* TODO: Implement clock_fine() and clock_fine_max_ticks() using another timer?
*/
#include <stdio.h> /*for debug printf*/
#include "sys/clock.h"
#include "sys/etimer.h"
#include "cc2430_sfr.h"
/*Sleep timer runs on the 32k RC osc. */
/* One clock tick is 7.8 ms */
#define TICK_VAL (32768/128)
#define MAX_TICKS (~((clock_time_t)0) / 2)
/* Used in sleep timer interrupt for calculating the next interrupt time */
static unsigned long timer_value;
/*starts calculating the ticks right after reset*/
static volatile clock_time_t count = 0;
/*calculates seconds*/
static volatile clock_time_t seconds = 0;
/*---------------------------------------------------------------------------*/
/**
* 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);
}
/*---------------------------------------------------------------------------*/
clock_time_t
clock_time(void)
{
return count;
}
/*---------------------------------------------------------------------------*/
CCIF unsigned long
clock_seconds(void)
{
return seconds;
}
/*---------------------------------------------------------------------------*/
void
clock_init(void)
{
CLKCON = OSC32K | TICKSPD2|TICKSPD1|TICKSPD0; /*tickspeed 250 kHz*/
/*Initialize tick value*/
timer_value = ST0; /*sleep timer 0. 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; /*interrupt enable for sleep timers. STIE=Interrupt mask, CPU. */
}
/*---------------------------------------------------------------------------*/
void
cc2430_clock_ISR( void ) __interrupt (ST_VECTOR)
{
IEN0_EA = 0; /*interrupt disable*/
/* When using the cooperative scheduler the timer 2 ISR is only
required to increment the RTOS tick count. */
/*Read value of the ST0,ST1,ST2 and then 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(etimer_pending() &&
(etimer_next_expiration_time() - count - 1) > MAX_TICKS) { /*core/sys/etimer.c*/
etimer_request_poll();
}
IRCON &= ~STIF; /*IRCON.STIF=Sleep timer interrupt flag. This flag called this interrupt func, now reset it*/
IEN0_EA = 1; /*interrupt enable*/
}
/*---------------------------------------------------------------------------*/