97 lines
3.8 KiB
C
97 lines
3.8 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-rtimer cc2538 rtimer
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*
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* Implementation of the rtimer module for the cc2538
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*
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* The rtimer runs on the Sleep Timer. This is a design choice, as many parts
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* of Contiki like rtimers with a value of RTIMER_ARCH_SECOND being a power of
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* two. The ST runs on the 32kHz clock, which can provide us with an excellent
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* value of 32768 for RTIMER_ARCH_SECOND.
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*
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* Additionally, since the ST keeps running in PM2, we can do things like drop
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* to PM2 and schedule a wake-up time through the rtimer API.
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*
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* \note If the 32kHz clock is running on the 32kHz RC OSC, the rtimer is
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* not 100% accurate (the RC OSC does not run at exactly 32.768 kHz). For
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* applications requiring higher accuracy, the 32kHz clock should be changed to
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* use the XOSC as its source. To see which low-frequency OSC the 32kHz clock
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* is running on, see cpu/cc2538/clock.c.
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*
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* \sa cpu/cc2538/clock.c
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* @{
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*/
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/**
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* \file
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* Header file for the cc2538 rtimer driver
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*/
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#ifndef RTIMER_ARCH_H_
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#define RTIMER_ARCH_H_
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#include "contiki.h"
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#include "dev/gptimer.h"
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#define RTIMER_ARCH_SECOND 32768
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/* Do the math in 32bits to save precision.
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* Round to nearest integer rather than truncate. */
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#define US_TO_RTIMERTICKS(US) ((US) >= 0 ? \
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(((int32_t)(US) * (RTIMER_ARCH_SECOND) + 500000) / 1000000L) : \
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((int32_t)(US) * (RTIMER_ARCH_SECOND) - 500000) / 1000000L)
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#define RTIMERTICKS_TO_US(T) ((T) >= 0 ? \
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(((int32_t)(T) * 1000000L + ((RTIMER_ARCH_SECOND) / 2)) / (RTIMER_ARCH_SECOND)) : \
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((int32_t)(T) * 1000000L - ((RTIMER_ARCH_SECOND) / 2)) / (RTIMER_ARCH_SECOND))
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/* A 64-bit version because the 32-bit one cannot handle T >= 4295 ticks.
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Intended only for positive values of T. */
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#define RTIMERTICKS_TO_US_64(T) ((uint32_t)(((uint64_t)(T) * 1000000 + ((RTIMER_ARCH_SECOND) / 2)) / (RTIMER_ARCH_SECOND)))
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/** \sa RTIMER_NOW() */
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rtimer_clock_t rtimer_arch_now(void);
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/**
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* \brief Get the time of the next scheduled rtimer trigger
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* \return The time next rtimer ISR is scheduled for
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*/
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rtimer_clock_t rtimer_arch_next_trigger(void);
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#endif /* RTIMER_ARCH_H_ */
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/**
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* @}
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* @}
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*/
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