2 FreeRTOS.org V4.7.1 - Copyright (C) 2003-2008 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 2 of the License, or
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9 (at your option) any later version.
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11 FreeRTOS.org is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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16 You should have received a copy of the GNU General Public License
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17 along with FreeRTOS.org; if not, write to the Free Software
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18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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20 A special exception to the GPL can be applied should you wish to distribute
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21 a combined work that includes FreeRTOS.org, without being obliged to provide
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22 the source code for any proprietary components. See the licensing section
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23 of http://www.FreeRTOS.org for full details of how and when the exception
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26 ***************************************************************************
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28 Please ensure to read the configuration and relevant port sections of the
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29 online documentation.
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31 +++ http://www.FreeRTOS.org +++
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32 Documentation, latest information, license and contact details.
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34 +++ http://www.SafeRTOS.com +++
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35 A version that is certified for use in safety critical systems.
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37 +++ http://www.OpenRTOS.com +++
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38 Commercial support, development, porting, licensing and training services.
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40 ***************************************************************************
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45 + ISRcode is pulled inline and portTICKisr() is therefore
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46 deleted from this file.
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48 + Prescaler logic for Timer1 added to allow for a wider
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54 #include <FreeRTOS.h>
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57 /* IO port constants. */
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58 #define portBIT_SET (1)
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59 #define portBIT_CLEAR (0)
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62 * Hardware setup for the tick.
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63 * We use a compare match on timer1. Depending on MPU-frequency
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64 * and requested tickrate, a prescaled value with a matching
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65 * prescaler are determined.
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67 #define portTIMER_COMPARE_BASE ((APROCFREQ/4)/configTICK_RATE_HZ)
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69 #if portTIMER_COMPARE_BASE < 0x10000
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70 #define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE)
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71 #define portTIMER_COMPARE_PS1 (portBIT_CLEAR)
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72 #define portTIMER_COMPARE_PS0 (portBIT_CLEAR)
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73 #elif portTIMER_COMPARE_BASE < 0x20000
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74 #define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE / 2)
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75 #define portTIMER_COMPARE_PS1 (portBIT_CLEAR)
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76 #define portTIMER_COMPARE_PS0 (portBIT_SET)
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77 #elif portTIMER_COMPARE_BASE < 0x40000
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78 #define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE / 4)
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79 #define portTIMER_COMPARE_PS1 (portBIT_SET)
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80 #define portTIMER_COMPARE_PS0 (portBIT_CLEAR)
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81 #elif portTIMER_COMPARE_BASE < 0x80000
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82 #define portTIMER_COMPARE_VALUE (portTIMER_COMPARE_BASE / 8)
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83 #define portTIMER_COMPARE_PS1 (portBIT_SET)
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84 #define portTIMER_COMPARE_PS0 (portBIT_SET)
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86 #error "TickRate out of range"
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89 /*-----------------------------------------------------------*/
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92 * Setup a timer for a regular tick.
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94 void portSetupTick( void )
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97 * Interrupts are disabled when this function is called.
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102 * Provide the tick interrupt using a compare match on timer1.
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106 * Set the compare match value.
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108 CCPR1H = ( unsigned portCHAR ) ( ( portTIMER_COMPARE_VALUE >> 8 ) & 0xff );
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109 CCPR1L = ( unsigned portCHAR ) ( portTIMER_COMPARE_VALUE & 0xff );
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112 * Set Compare Special Event Trigger Mode
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114 bCCP1M3 = portBIT_SET;
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115 bCCP1M2 = portBIT_CLEAR;
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116 bCCP1M1 = portBIT_SET;
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117 bCCP1M0 = portBIT_SET;
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120 * Enable CCP1 interrupt
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122 bCCP1IE = portBIT_SET;
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125 * We are only going to use the global interrupt bit, so disable
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126 * interruptpriorities and enable peripheral interrupts.
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128 bIPEN = portBIT_CLEAR;
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129 bPEIE = portBIT_SET;
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133 * It will produce the system tick.
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137 * Clear the time count
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139 TMR1H = ( unsigned portCHAR ) 0x00;
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140 TMR1L = ( unsigned portCHAR ) 0x00;
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145 bRD16 = portBIT_SET; // 16-bit
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146 bT1CKPS1 = portTIMER_COMPARE_PS1; // prescaler
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147 bT1CKPS0 = portTIMER_COMPARE_PS0; // prescaler
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148 bT1OSCEN = portBIT_SET; // Oscillator enable
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149 bT1SYNC = portBIT_SET; // No external clock sync
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150 bTMR1CS = portBIT_CLEAR; // Internal clock
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152 bTMR1ON = portBIT_SET; // Start timer1
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