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https://github.com/oliverschmidt/contiki.git
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40f49948e6
This commit adds cpu, platform and example files, providing support for running Contiki on TI's cc2538 DK
228 lines
6.9 KiB
C
228 lines
6.9 KiB
C
/*
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* Copyright (c) 2012, Texas Instruments Incorporated - http://www.ti.com/
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* \addtogroup cc2538
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* @{
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*
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* \defgroup cc2538-clock cc2538 Clock
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*
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* Implementation of the clock module for the cc2538
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*
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* To implement the clock functionality, we use the SysTick peripheral on the
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* cortex-M3. We run the system clock at 16 MHz and we set the SysTick to give
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* us 128 interrupts / sec
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* @{
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*
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* \file
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* Clock driver implementation for the TI cc2538
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*/
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#include "contiki.h"
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#include "systick.h"
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#include "reg.h"
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#include "cpu.h"
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#include "dev/gptimer.h"
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#include "dev/sys-ctrl.h"
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#include "sys/energest.h"
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#include <stdint.h>
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/*---------------------------------------------------------------------------*/
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#define RELOAD_VALUE (125000 - 1) /** Fire 128 times / sec */
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static volatile clock_time_t count;
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static volatile unsigned long secs = 0;
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static volatile uint8_t second_countdown = CLOCK_SECOND;
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Arch-specific implementation of clock_init for the cc2538
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*
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* We initialise the SysTick to fire 128 interrupts per second, giving us a
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* value of 128 for CLOCK_SECOND
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*
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* We also initialise GPT0:Timer A, which is used by clock_delay_usec().
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* We use 16-bit range (individual), count-down, one-shot, no interrupts.
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* The system clock is at 16MHz giving us 62.5 nano sec ticks for Timer A.
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* Prescaled by 16 gives us a very convenient 1 tick per usec
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*/
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void
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clock_init(void)
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{
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count = 0;
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REG(SYSTICK_STRELOAD) = RELOAD_VALUE;
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/* System clock source, Enable */
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REG(SYSTICK_STCTRL) |= SYSTICK_STCTRL_CLK_SRC | SYSTICK_STCTRL_ENABLE;
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/* Enable the SysTick Interrupt */
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REG(SYSTICK_STCTRL) |= SYSTICK_STCTRL_INTEN;
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/*
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* Remove the clock gate to enable GPT0 and then initialise it
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* We only use GPT0 for clock_delay_usec. We initialise it here so we can
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* have it ready when it's needed
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*/
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REG(SYS_CTRL_RCGCGPT) |= SYS_CTRL_RCGCGPT_GPT0;
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/* Make sure GPT0 is off */
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REG(GPT_0_BASE | GPTIMER_CTL) = 0;
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/* 16-bit */
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REG(GPT_0_BASE | GPTIMER_CFG) = 0x04;
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/* One-Shot, Count Down, No Interrupts */
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REG(GPT_0_BASE | GPTIMER_TAMR) = GPTIMER_TAMR_TAMR_ONE_SHOT;
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/* Prescale by 16 (thus, value 15 in TAPR) */
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REG(GPT_0_BASE | GPTIMER_TAPR) = 0x0F;
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}
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/*---------------------------------------------------------------------------*/
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CCIF clock_time_t
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clock_time(void)
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{
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return count;
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}
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/*---------------------------------------------------------------------------*/
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void
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clock_set_seconds(unsigned long sec)
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{
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secs = sec;
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}
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/*---------------------------------------------------------------------------*/
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CCIF unsigned long
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clock_seconds(void)
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{
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return secs;
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}
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/*---------------------------------------------------------------------------*/
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void
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clock_wait(clock_time_t i)
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{
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clock_time_t start;
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start = clock_time();
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while(clock_time() - start < (clock_time_t)i);
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Arch-specific implementation of clock_delay_usec for the cc2538
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* \param len Delay \e len uSecs
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*
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* See clock_init() for GPT0 Timer A's configuration
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*/
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void
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clock_delay_usec(uint16_t len)
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{
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REG(GPT_0_BASE | GPTIMER_TAILR) = len;
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REG(GPT_0_BASE | GPTIMER_CTL) |= GPTIMER_CTL_TAEN;
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/* One-Shot mode: TAEN will be cleared when the timer reaches 0 */
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while(REG(GPT_0_BASE | GPTIMER_CTL) & GPTIMER_CTL_TAEN);
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Obsolete delay function but we implement it here since some code
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* still uses it
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*/
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void
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clock_delay(unsigned int i)
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{
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clock_delay_usec(i);
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Adjust the clock by moving it forward by a number of ticks
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* \param ticks The number of ticks
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*
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* This function is useful when coming out of PM1/2, during which the system
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* clock is stopped. We adjust the clock by moving it forward by a number of
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* ticks equal to the deep sleep duration. We update the seconds counter if
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* we have to and we also do some housekeeping so that the next second will
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* increment when it is meant to.
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*
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* \note This function is only meant to be used by lpm_exit(). Applications
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* should really avoid calling this
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*/
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void
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clock_adjust(clock_time_t ticks)
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{
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/* Halt the SysTick while adjusting */
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REG(SYSTICK_STCTRL) &= ~SYSTICK_STCTRL_ENABLE;
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/* Moving forward by more than a second? */
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secs += ticks >> 7;
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/* Increment tick count */
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count += ticks;
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/*
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* Update internal second countdown so that next second change will actually
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* happen when it's meant to happen.
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*/
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second_countdown -= ticks;
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if(second_countdown == 0 || second_countdown > 128) {
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secs++;
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second_countdown -= 128;
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}
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/* Re-Start the SysTick */
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REG(SYSTICK_STCTRL) |= SYSTICK_STCTRL_ENABLE;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief The clock Interrupt Service Routine. It polls the etimer process
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* if an etimer has expired. It also updates the software clock tick and
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* seconds counter since reset.
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*/
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void
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clock_isr(void)
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{
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ENERGEST_ON(ENERGEST_TYPE_IRQ);
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count++;
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if(etimer_pending()) {
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etimer_request_poll();
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}
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if(--second_countdown == 0) {
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secs++;
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second_countdown = CLOCK_SECOND;
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}
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ENERGEST_OFF(ENERGEST_TYPE_IRQ);
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}
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/*---------------------------------------------------------------------------*/
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/**
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* @}
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* @}
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*/
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