begriffs open source - cmsis-freertos/blob - Demo/NEC_78K0R

1 /*

2 * FreeRTOS Kernel V10.1.1

4 *

5 * Permission is hereby granted, free of charge, to any person obtaining a copy of

6 * this software and associated documentation files (the "Software"), to deal in

7 * the Software without restriction, including without limitation the rights to

8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of

9 * the Software, and to permit persons to whom the Software is furnished to do so,

10 * subject to the following conditions:

11 *

12 * The above copyright notice and this permission notice shall be included in all

13 * copies or substantial portions of the Software.

14 *

15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS

17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR

18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER

19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN

20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

21 *

22 * http://www.FreeRTOS.org

23 * http://aws.amazon.com/freertos

24 *

25 * 1 tab == 4 spaces!

26 */

27

28 /*

29 * This file defines the button push task and ISR as described at the top of

30 * main.c. The ISR is called from a wrapper function defined in ButtonISR.s26.

31 */

32

33 /* Kernel includes. */

34 #include "FreeRTOS.h"

35 #include "task.h"

36 #include "semphr.h"

37

38 /* The LED output used by the button push task. */

39 #define butLED1 P7_bit.no7

40

41 /* A short delay used for button debouncing. */

42 #define butDEBOUNCE_DELAY ( 200 / portTICK_PERIOD_MS )

43

44 /* The semaphore used to synchronise the button push task with the interrupt. */

45 static SemaphoreHandle_t xButtonSemaphore;

46

47 /*

48 * The definition of the button task itself. See the comments at the top of

49 * main.c.

50 */

51 void vButtonTask( void *pvParameters )

52 {

53 /* Ensure the semaphore is created before it gets used. */

54 vSemaphoreCreateBinary( xButtonSemaphore );

55

56 for( ;; )

57 {

58 /* Block on the semaphore to wait for an interrupt event. The semaphore

59 is 'given' from vButtonISRHandler() below. Using portMAX_DELAY as the

60 block time will cause the task to block indefinitely provided

61 INCLUDE_vTaskSuspend is set to 1 in FreeRTOSConfig.h. */

62 xSemaphoreTake( xButtonSemaphore, portMAX_DELAY );

63

64 /* The button must have been pushed for this line to be executed.

65 Simply toggle the LED. */

66 butLED1 = !butLED1;

67

68 /* Wait a short time then clear any pending button pushes as a crude

69 method of debouncing the switch. xSemaphoreTake() uses a block time of

70 zero this time so it returns immediately rather than waiting for the

71 interrupt to occur. */

72 vTaskDelay( butDEBOUNCE_DELAY );

73 xSemaphoreTake( xButtonSemaphore, 0 );

74 }

75 }

76 /*-----------------------------------------------------------*/

77

78 /*

79 * The C portion of the interrupt handler. Interrupts are triggered by pushing

80 * the button on the target board. This interrupt can cause a context switch

81 * so has an assembly file wrapper defined within ButtonISR.s26.

82 */

83 void vButtonISRHandler( void )

84 {

85 short sHigherPriorityTaskWoken = pdFALSE;

86

87 /* 'Give' the semaphore to unblock the button task. */

88 xSemaphoreGiveFromISR( xButtonSemaphore, &sHigherPriorityTaskWoken );

89

90 /* If giving the semaphore unblocked a task, and the unblocked task has a

91 priority that is higher than the currently running task, then

92 sHigherPriorityTaskWoken will have been set to pdTRUE. Passing a pdTRUE

93 value to portYIELD_FROM_ISR() will cause this interrupt to return directly

94 to the higher priority unblocked task. */

95 portYIELD_FROM_ISR( sHigherPriorityTaskWoken );

96 }

97 /*-----------------------------------------------------------*/