begriffs open source - cmsis-freertos/blob - Demo/Common/Minimal/flash.c

1 /*

4

5 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

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7 This file is part of the FreeRTOS distribution.

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9 FreeRTOS is free software; you can redistribute it and/or modify it under

10 the terms of the GNU General Public License (version 2) as published by the

11 Free Software Foundation >>>> AND MODIFIED BY <<<< the FreeRTOS exception.

12

13 ***************************************************************************

14 >>! NOTE: The modification to the GPL is included to allow you to !<<

15 >>! distribute a combined work that includes FreeRTOS without being !<<

16 >>! obliged to provide the source code for proprietary components !<<

17 >>! outside of the FreeRTOS kernel. !<<

18 ***************************************************************************

19

20 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY

21 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

22 FOR A PARTICULAR PURPOSE. Full license text is available on the following

23 link: http://www.freertos.org/a00114.html

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25 ***************************************************************************

26 * *

27 * FreeRTOS provides completely free yet professionally developed, *

28 * robust, strictly quality controlled, supported, and cross *

29 * platform software that is more than just the market leader, it *

30 * is the industry's de facto standard. *

31 * *

32 * Help yourself get started quickly while simultaneously helping *

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34 * tutorial book, reference manual, or both: *

35 * http://www.FreeRTOS.org/Documentation *

36 * *

37 ***************************************************************************

38

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65 mission critical applications that require provable dependability.

66

67 1 tab == 4 spaces!

68 */

69

70 /**

71 * This version of flash .c is for use on systems that have limited stack space

72 * and no display facilities. The complete version can be found in the

73 * Demo/Common/Full directory.

74 *

75 * Three tasks are created, each of which flash an LED at a different rate. The first

76 * LED flashes every 200ms, the second every 400ms, the third every 600ms.

77 *

78 * The LED flash tasks provide instant visual feedback. They show that the scheduler

79 * is still operational.

80 *

81 */

82

83

84 #include <stdlib.h>

85

86 /* Scheduler include files. */

87 #include "FreeRTOS.h"

88 #include "task.h"

89

90 /* Demo program include files. */

91 #include "partest.h"

92 #include "flash.h"

93

94 #define ledSTACK_SIZE configMINIMAL_STACK_SIZE

95 #define ledNUMBER_OF_LEDS ( 3 )

96 #define ledFLASH_RATE_BASE ( ( TickType_t ) 333 )

97

98 /* Variable used by the created tasks to calculate the LED number to use, and

99 the rate at which they should flash the LED. */

100 static volatile UBaseType_t uxFlashTaskNumber = 0;

101

102 /* The task that is created three times. */

103 static portTASK_FUNCTION_PROTO( vLEDFlashTask, pvParameters );

104

105 /*-----------------------------------------------------------*/

106

107 void vStartLEDFlashTasks( UBaseType_t uxPriority )

108 {

109 BaseType_t xLEDTask;

110

111 /* Create the three tasks. */

112 for( xLEDTask = 0; xLEDTask < ledNUMBER_OF_LEDS; ++xLEDTask )

113 {

114 /* Spawn the task. */

115 xTaskCreate( vLEDFlashTask, "LEDx", ledSTACK_SIZE, NULL, uxPriority, ( TaskHandle_t * ) NULL );

116 }

117 }

118 /*-----------------------------------------------------------*/

119

120 static portTASK_FUNCTION( vLEDFlashTask, pvParameters )

121 {

122 TickType_t xFlashRate, xLastFlashTime;

123 UBaseType_t uxLED;

124

125 /* The parameters are not used. */

126 ( void ) pvParameters;

127

128 /* Calculate the LED and flash rate. */

129 portENTER_CRITICAL();

130 {

131 /* See which of the eight LED's we should use. */

132 uxLED = uxFlashTaskNumber;

133

134 /* Update so the next task uses the next LED. */

135 uxFlashTaskNumber++;

136 }

137 portEXIT_CRITICAL();

138

139 xFlashRate = ledFLASH_RATE_BASE + ( ledFLASH_RATE_BASE * ( TickType_t ) uxLED );

140 xFlashRate /= portTICK_PERIOD_MS;

141

142 /* We will turn the LED on and off again in the delay period, so each

143 delay is only half the total period. */

144 xFlashRate /= ( TickType_t ) 2;

145

146 /* We need to initialise xLastFlashTime prior to the first call to

147 vTaskDelayUntil(). */

148 xLastFlashTime = xTaskGetTickCount();

149

150 for(;;)

151 {

152 /* Delay for half the flash period then turn the LED on. */

153 vTaskDelayUntil( &xLastFlashTime, xFlashRate );

154 vParTestToggleLED( uxLED );

155

156 /* Delay for half the flash period then turn the LED off. */

157 vTaskDelayUntil( &xLastFlashTime, xFlashRate );

158 vParTestToggleLED( uxLED );

159 }

160 } /*lint !e715 !e818 !e830 Function definition must be standard for task creation. */

161