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| − | [[category: RTOS Tutorials]] | + | #REDIRECT[[4. Understanding the task switching depending upon priorities]] |
| − | [[User:Amruta|Amruta]] ([[User talk:Amruta|talk]]) 13:43, 8 April 2015 (IST)
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| − | ----
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| − | ==Intro==
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| − | In last tutorial we saw the effect of vTaskDelay() function.
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| − | Now we will see how kernel does task switching depending upon the priorities.
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| − | If you are not familiar with what is task switching, check this.
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| − | ==Code==
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| − | <syntaxhighlight>
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| − | /* Scheduler include files. */
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| − | #include "FreeRtOSConfig.h"
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| − | #include "FreeRTOS.h"
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| − | #include "task.h"
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| − | #include "croutine.h"
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| − | #include "uart.h" /* Explore Embedded UART library */
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| − | xTaskHandle TaskHandle_1;
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| − | xTaskHandle TaskHandle_2;
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| − | xTaskHandle TaskHandle_3;
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| − | xTaskHandle TaskHandle_4;
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| − | xTaskHandle TaskHandle_5;
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| − | /* Local Tasks declaration */
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| − | static void MyTask1(void* pvParameters);
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| − | static void MyTask2(void* pvParameters);
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| − | static void MyTask3(void* pvParameters);
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| − | static void MyTask4(void* pvParameters);
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| − | static void MyTask5(void* pvParameters);
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| − | static void MyIdleTask(void* pvParameters);
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| − | #define LED_IdleTask 0x01u
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| − | #define LED_Task1 0x02u
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| − | #define LED_Task2 0x04u
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| − | #define LED_Task3 0x08u
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| − | #define LED_Task4 0x10u
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| − | #define LED_Task5 0x20u
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| − | #define LED_PORT LPC_GPIO2->FIOPIN
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| − | int main(void)
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| − | {
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| − | SystemInit(); /* Initialize the microcontroller system */
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| − | LPC_GPIO2->FIODIR = 0xffffffffu;
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| − | UART_Init(38400); /* Initialize the Uart module */
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| − | /* Create the three tasks with priorities 1,2,3 */
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| − | xTaskCreate( MyTask1, ( signed char * )"Task1", configMINIMAL_STACK_SIZE, NULL, 1, &TaskHandle_1);
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| − | xTaskCreate( MyTask3, ( signed char * )"Task3", configMINIMAL_STACK_SIZE, NULL, 3, &TaskHandle_3 );
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| − | xTaskCreate( MyIdleTask, ( signed char * )"IdleTask", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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| − | UART_Printf("\n\rIn main function, invoking scheduler");
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| − |
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| − | vTaskStartScheduler(); /* Start the schedular */
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| − | while(1);
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| − | }
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| − | static void MyTask1(void* pvParameters)
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| − | {
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| − | LED_PORT = LED_Task1; /* Led to indicate the execution of Task1*/
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| − | UART_Printf("\n\rIn Task1");
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| − | vTaskDelete(TaskHandle_1);
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| − | }
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| − | static void MyTask2(void* pvParameters)
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| − | {
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| − | LED_PORT = LED_Task2; /* Led to indicate the execution of Task2*/
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| − | UART_Printf("\n\rIn Task2 ");
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| − | vTaskDelete(TaskHandle_2);
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| − | }
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| − | static void MyTask3(void* pvParameters)
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| − | {
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| − | LED_PORT = LED_Task3; /* Led to indicate the execution of Task3*/
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| − | UART_Printf("\n\rTask3, creating new tasks 2");
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| − | /* Create two new tasks 2, 4 */
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| − | xTaskCreate( MyTask2, ( signed char * )"Task2", configMINIMAL_STACK_SIZE, NULL, 2, &TaskHandle_2);
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| − | UART_Printf("\n\rTask3, creating new tasks 4");
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| − | xTaskCreate( MyTask4, ( signed char * )"Task4", configMINIMAL_STACK_SIZE, NULL, 4, &TaskHandle_4);
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| − | LED_PORT = LED_Task3; /* Led to indicate the execution of Task3*/
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| − | UART_Printf("\n\rBack in Task3, Creating Task5");
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| − | xTaskCreate( MyTask5, ( signed char * )"Task5", configMINIMAL_STACK_SIZE, NULL, 5, &TaskHandle_5);
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| − | LED_PORT = LED_Task3; /* Led to indicate the execution of Task3*/
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| − | UART_Printf("\n\rBack in Task3, Exiting task3");
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| − | vTaskDelete(TaskHandle_3);
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| − | }
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| − | static void MyTask4(void* pvParameters)
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| − | {
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| − | LED_PORT = LED_Task4; /* Led to indicate the execution of Task4*/
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| − | UART_Printf("\n\rIn Task4");
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| − | vTaskDelete(TaskHandle_4);
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| − | }
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| − | static void MyTask5(void* pvParameters)
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| − | {
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| − | LED_PORT = LED_Task5; /* Led to indicate the execution of Task4*/
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| − | UART_Printf("\n\rIn Task5");
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| − | vTaskDelete(TaskHandle_5);
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| − | }
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| − | static void MyIdleTask(void* pvParameters)
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| − | {
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| − | while(1)
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| − | {
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| − | LED_PORT = LED_IdleTask; /* Led to indicate the execution of Idle Task*/
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| − | UART_Printf("\n\rIn idle state");
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| − | }
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| − | }
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| − | </syntaxhighlight>
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| − | {{DISQUS}}
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