a082aebc77
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3431 42af7a65-404d-4744-a932-0658087f49c3
107 lines
4.2 KiB
C
107 lines
4.2 KiB
C
/****************************************************************************
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* config/vsn/src/rtac.c
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* arch/arm/src/board/rtac.c
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*
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* Copyright (C) 2011 Uros Platise. All rights reserved.
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*
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* Authors: Uros Platise <uros.platise@isotel.eu>
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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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*
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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
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* 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 OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/** \file
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* \author Uros Platise
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* \brief Real Time Alarm Clock
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*
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* Implementation of the Real-Time Alarm Clock as per SNP Specifications.
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* It provides real-time and phase controlled timer module while it
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* cooperates with hardware RTC for low-power operation.
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*
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* It provides a replacement for a system 32-bit UTC time/date counter.
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*
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* It runs at maximum STM32 allowed precision of 16384 Hz, providing
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* resolution of 61 us, required by the Sensor Network Protocol.
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*/
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/****************************************************************************
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* Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Data
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****************************************************************************/
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/** Execute from a group of events
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**/
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int rtac_execg(int group)
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{
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// called by each thread to spawn its apps given by its ID or group ID of
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// multiple threads, when group parameter is set.
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}
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/** Wait and execute from a group of events
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**/
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int rtac_waitg(int group, int time)
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{
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// blocking variant of rtac_exec with timeout if specified
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}
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/** Power optimization of base systick timer
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*
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* 1. Simple method to skip wake-ups:
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* - ask timers about the min. period, which is Ns * systick
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* - set the preload register with floor(Ns) * DEFAULT_PRELOAD
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* - on wake-up call routines Ns times.
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*
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* 2. If intermediate ISR occuried then:
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* - check how many periods have passed by reading the counter: Np
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* - set the new counter value as (counter % DEFAULT_PRELOAD)
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* - call timer routines Np times; the next call is as usual, starting
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* at 1. point above
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*
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* This is okay if ISR's do not read timers, if they read timers then:
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* - on ISR wake-up the code described under 2. must be called first
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* (on wake-up from IDLE)
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*
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* BUT: the problem is that SYSTICK does not run in Stop mode but RTC
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* only, so it might be better to replace SYSTICK with RTAC (this
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* module) and do the job above, permitting ultra low power modes of
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* 25 uA or further down to 5 uA.
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*/
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