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140 lines
4.4 KiB
C
140 lines
4.4 KiB
C
/*
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* FreeRTOS Kernel <DEVELOPMENT BRANCH>
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* Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* SPDX-License-Identifier: MIT
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* https://www.FreeRTOS.org
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* https://github.com/FreeRTOS
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*
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*/
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/*
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Changes from V3.0.0
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+ ISRcode is pulled inline and portTICKisr() is therefore
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deleted from this file.
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+ Prescaler logic for Timer1 added to allow for a wider
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range of TickRates.
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Changes from V3.0.1
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*/
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#include <FreeRTOS.h>
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#include <task.h>
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/* IO port constants. */
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#define portBIT_SET (1)
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#define portBIT_CLEAR (0)
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/*
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* Hardware setup for the tick.
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* We use a compare match on timer1. Depending on MPU-frequency
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* and requested tickrate, a prescaled value with a matching
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* prescaler are determined.
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*/
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#define portTIMER_COMPARE_BASE ((APROCFREQ/4)/configTICK_RATE_HZ)
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#if portTIMER_COMPARE_BASE < 0x10000
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#define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE)
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#define portTIMER_COMPARE_PS1 (portBIT_CLEAR)
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#define portTIMER_COMPARE_PS0 (portBIT_CLEAR)
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#elif portTIMER_COMPARE_BASE < 0x20000
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#define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE / 2)
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#define portTIMER_COMPARE_PS1 (portBIT_CLEAR)
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#define portTIMER_COMPARE_PS0 (portBIT_SET)
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#elif portTIMER_COMPARE_BASE < 0x40000
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#define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE / 4)
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#define portTIMER_COMPARE_PS1 (portBIT_SET)
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#define portTIMER_COMPARE_PS0 (portBIT_CLEAR)
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#elif portTIMER_COMPARE_BASE < 0x80000
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#define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE / 8)
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#define portTIMER_COMPARE_PS1 (portBIT_SET)
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#define portTIMER_COMPARE_PS0 (portBIT_SET)
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#else
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#error "TickRate out of range"
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#endif
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/*-----------------------------------------------------------*/
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/*
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* Setup a timer for a regular tick.
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*/
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void portSetupTick( void )
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{
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/*
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* Interrupts are disabled when this function is called.
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*/
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/*
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* Setup CCP1
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* Provide the tick interrupt using a compare match on timer1.
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*/
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/*
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* Set the compare match value.
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*/
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CCPR1H = ( uint8_t ) ( ( portTIMER_COMPARE_VALUE >> 8 ) & 0xff );
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CCPR1L = ( uint8_t ) ( portTIMER_COMPARE_VALUE & 0xff );
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/*
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* Set Compare Special Event Trigger Mode
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*/
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bCCP1M3 = portBIT_SET;
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bCCP1M2 = portBIT_CLEAR;
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bCCP1M1 = portBIT_SET;
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bCCP1M0 = portBIT_SET;
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/*
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* Enable CCP1 interrupt
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*/
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bCCP1IE = portBIT_SET;
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/*
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* We are only going to use the global interrupt bit, so disable
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* interruptpriorities and enable peripheral interrupts.
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*/
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bIPEN = portBIT_CLEAR;
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bPEIE = portBIT_SET;
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/*
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* Set up timer1
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* It will produce the system tick.
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*/
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/*
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* Clear the time count
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*/
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TMR1H = ( uint8_t ) 0x00;
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TMR1L = ( uint8_t ) 0x00;
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/*
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* Setup the timer
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*/
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bRD16 = portBIT_SET; // 16-bit
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bT1CKPS1 = portTIMER_COMPARE_PS1; // prescaler
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bT1CKPS0 = portTIMER_COMPARE_PS0; // prescaler
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bT1OSCEN = portBIT_SET; // Oscillator enable
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bT1SYNC = portBIT_SET; // No external clock sync
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bTMR1CS = portBIT_CLEAR; // Internal clock
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bTMR1ON = portBIT_SET; // Start timer1
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}
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