2 FreeRTOS V6.0.1 - Copyright (C) 2009 Real Time Engineers Ltd.
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4 ***************************************************************************
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8 * + New to FreeRTOS, *
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9 * + Wanting to learn FreeRTOS or multitasking in general quickly *
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10 * + Looking for basic training, *
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11 * + Wanting to improve your FreeRTOS skills and productivity *
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13 * then take a look at the FreeRTOS eBook *
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15 * "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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16 * http://www.FreeRTOS.org/Documentation *
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18 * A pdf reference manual is also available. Both are usually delivered *
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19 * to your inbox within 20 minutes to two hours when purchased between 8am *
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20 * and 8pm GMT (although please allow up to 24 hours in case of *
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21 * exceptional circumstances). Thank you for your support! *
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23 ***************************************************************************
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25 This file is part of the FreeRTOS distribution.
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27 FreeRTOS is free software; you can redistribute it and/or modify it under
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28 the terms of the GNU General Public License (version 2) as published by the
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29 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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30 ***NOTE*** The exception to the GPL is included to allow you to distribute
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31 a combined work that includes FreeRTOS without being obliged to provide the
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32 source code for proprietary components outside of the FreeRTOS kernel.
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33 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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34 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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35 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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36 more details. You should have received a copy of the GNU General Public
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37 License and the FreeRTOS license exception along with FreeRTOS; if not it
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38 can be viewed here: http://www.freertos.org/a00114.html and also obtained
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39 by writing to Richard Barry, contact details for whom are available on the
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44 http://www.FreeRTOS.org - Documentation, latest information, license and
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47 http://www.SafeRTOS.com - A version that is certified for use in safety
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50 http://www.OpenRTOS.com - Commercial support, development, porting,
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51 licensing and training services.
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56 + ISRcode is pulled inline and portTICKisr() is therefore
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57 deleted from this file.
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59 + Prescaler logic for Timer1 added to allow for a wider
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65 #include <FreeRTOS.h>
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68 /* IO port constants. */
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69 #define portBIT_SET (1)
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70 #define portBIT_CLEAR (0)
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73 * Hardware setup for the tick.
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74 * We use a compare match on timer1. Depending on MPU-frequency
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75 * and requested tickrate, a prescaled value with a matching
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76 * prescaler are determined.
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78 #define portTIMER_COMPARE_BASE ((APROCFREQ/4)/configTICK_RATE_HZ)
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80 #if portTIMER_COMPARE_BASE < 0x10000
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81 #define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE)
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82 #define portTIMER_COMPARE_PS1 (portBIT_CLEAR)
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83 #define portTIMER_COMPARE_PS0 (portBIT_CLEAR)
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84 #elif portTIMER_COMPARE_BASE < 0x20000
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85 #define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE / 2)
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86 #define portTIMER_COMPARE_PS1 (portBIT_CLEAR)
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87 #define portTIMER_COMPARE_PS0 (portBIT_SET)
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88 #elif portTIMER_COMPARE_BASE < 0x40000
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89 #define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE / 4)
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90 #define portTIMER_COMPARE_PS1 (portBIT_SET)
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91 #define portTIMER_COMPARE_PS0 (portBIT_CLEAR)
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92 #elif portTIMER_COMPARE_BASE < 0x80000
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93 #define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE / 8)
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94 #define portTIMER_COMPARE_PS1 (portBIT_SET)
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95 #define portTIMER_COMPARE_PS0 (portBIT_SET)
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97 #error "TickRate out of range"
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100 /*-----------------------------------------------------------*/
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103 * Setup a timer for a regular tick.
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105 void portSetupTick( void )
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108 * Interrupts are disabled when this function is called.
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113 * Provide the tick interrupt using a compare match on timer1.
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117 * Set the compare match value.
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119 CCPR1H = ( unsigned char ) ( ( portTIMER_COMPARE_VALUE >> 8 ) & 0xff );
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120 CCPR1L = ( unsigned char ) ( portTIMER_COMPARE_VALUE & 0xff );
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123 * Set Compare Special Event Trigger Mode
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125 bCCP1M3 = portBIT_SET;
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126 bCCP1M2 = portBIT_CLEAR;
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127 bCCP1M1 = portBIT_SET;
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128 bCCP1M0 = portBIT_SET;
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131 * Enable CCP1 interrupt
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133 bCCP1IE = portBIT_SET;
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136 * We are only going to use the global interrupt bit, so disable
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137 * interruptpriorities and enable peripheral interrupts.
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139 bIPEN = portBIT_CLEAR;
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140 bPEIE = portBIT_SET;
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144 * It will produce the system tick.
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148 * Clear the time count
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150 TMR1H = ( unsigned char ) 0x00;
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151 TMR1L = ( unsigned char ) 0x00;
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156 bRD16 = portBIT_SET; // 16-bit
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157 bT1CKPS1 = portTIMER_COMPARE_PS1; // prescaler
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158 bT1CKPS0 = portTIMER_COMPARE_PS0; // prescaler
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159 bT1OSCEN = portBIT_SET; // Oscillator enable
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160 bT1SYNC = portBIT_SET; // No external clock sync
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161 bTMR1CS = portBIT_CLEAR; // Internal clock
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163 bTMR1ON = portBIT_SET; // Start timer1
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