2 * FreeRTOS Kernel V10.3.0
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3 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
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6 * this software and associated documentation files (the "Software"), to deal in
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7 * the Software without restriction, including without limitation the rights to
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8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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9 * the Software, and to permit persons to whom the Software is furnished to do so,
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10 * subject to the following conditions:
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12 * The above copyright notice and this permission notice shall be included in all
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13 * copies or substantial portions of the Software.
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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22 * http://www.FreeRTOS.org
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23 * http://aws.amazon.com/freertos
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25 * 1 tab == 4 spaces!
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30 + ISRcode is pulled inline and portTICKisr() is therefore
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31 deleted from this file.
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33 + Prescaler logic for Timer1 added to allow for a wider
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39 #include <FreeRTOS.h>
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42 /* IO port constants. */
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43 #define portBIT_SET (1)
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44 #define portBIT_CLEAR (0)
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47 * Hardware setup for the tick.
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48 * We use a compare match on timer1. Depending on MPU-frequency
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49 * and requested tickrate, a prescaled value with a matching
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50 * prescaler are determined.
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52 #define portTIMER_COMPARE_BASE ((APROCFREQ/4)/configTICK_RATE_HZ)
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54 #if portTIMER_COMPARE_BASE < 0x10000
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55 #define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE)
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56 #define portTIMER_COMPARE_PS1 (portBIT_CLEAR)
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57 #define portTIMER_COMPARE_PS0 (portBIT_CLEAR)
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58 #elif portTIMER_COMPARE_BASE < 0x20000
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59 #define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE / 2)
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60 #define portTIMER_COMPARE_PS1 (portBIT_CLEAR)
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61 #define portTIMER_COMPARE_PS0 (portBIT_SET)
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62 #elif portTIMER_COMPARE_BASE < 0x40000
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63 #define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE / 4)
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64 #define portTIMER_COMPARE_PS1 (portBIT_SET)
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65 #define portTIMER_COMPARE_PS0 (portBIT_CLEAR)
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66 #elif portTIMER_COMPARE_BASE < 0x80000
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67 #define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE / 8)
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68 #define portTIMER_COMPARE_PS1 (portBIT_SET)
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69 #define portTIMER_COMPARE_PS0 (portBIT_SET)
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71 #error "TickRate out of range"
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74 /*-----------------------------------------------------------*/
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77 * Setup a timer for a regular tick.
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79 void portSetupTick( void )
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82 * Interrupts are disabled when this function is called.
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87 * Provide the tick interrupt using a compare match on timer1.
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91 * Set the compare match value.
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93 CCPR1H = ( uint8_t ) ( ( portTIMER_COMPARE_VALUE >> 8 ) & 0xff );
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94 CCPR1L = ( uint8_t ) ( portTIMER_COMPARE_VALUE & 0xff );
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97 * Set Compare Special Event Trigger Mode
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99 bCCP1M3 = portBIT_SET;
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100 bCCP1M2 = portBIT_CLEAR;
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101 bCCP1M1 = portBIT_SET;
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102 bCCP1M0 = portBIT_SET;
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105 * Enable CCP1 interrupt
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107 bCCP1IE = portBIT_SET;
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110 * We are only going to use the global interrupt bit, so disable
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111 * interruptpriorities and enable peripheral interrupts.
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113 bIPEN = portBIT_CLEAR;
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114 bPEIE = portBIT_SET;
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118 * It will produce the system tick.
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122 * Clear the time count
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124 TMR1H = ( uint8_t ) 0x00;
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125 TMR1L = ( uint8_t ) 0x00;
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130 bRD16 = portBIT_SET; // 16-bit
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131 bT1CKPS1 = portTIMER_COMPARE_PS1; // prescaler
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132 bT1CKPS0 = portTIMER_COMPARE_PS0; // prescaler
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133 bT1OSCEN = portBIT_SET; // Oscillator enable
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134 bT1SYNC = portBIT_SET; // No external clock sync
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135 bTMR1CS = portBIT_CLEAR; // Internal clock
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137 bTMR1ON = portBIT_SET; // Start timer1
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