freeRTOS stack size configuration

Relas — Thu, 07 Nov 2024 07:44:02 GMT

I am currently learning FreeRTOS on the LPC51U68 development board (OM40005). I have created 7 tasks for testing and am using the RTOS task list monitor provided by MCUXpresso IDE.

I noticed that the stack sizes displayed in the task list don't match the configurations I set.

Could this be related to memory alignment?

Where can I check the rules for configuration differences?

Below is the code I modified from the freertos_hello example.

* SPDX-License-Identifier: BSD-3-Clause

/* FreeRTOS kernel includes. */

#include "FreeRTOS.h"

#include "task.h"

#include "queue.h"

#include "timers.h"

/* Freescale includes. */

#include "fsl_device_registers.h"

#include "fsl_debug_console.h"

#include "pin_mux.h"

#include "board.h"

#include <stdbool.h>

/*******************************************************************************

* Definitions

******************************************************************************/

/* Task priorities. */

#define hello_task_PRIORITY (configMAX_PRIORITIES - 1)

/*******************************************************************************

* Prototypes

******************************************************************************/

static void task1(void *pvParameters);

static void task2(void *pvParameters);

static void task3(void *pvParameters);

static void task4(void *pvParameters);

static void task5(void *pvParameters);

static void task6(void *pvParameters);

static void task7(void *pvParameters);

/*******************************************************************************

* Code

******************************************************************************/

/*!

* @brief Application entry point.

int main(void)

{

/* Init board hardware. */

/* attach 12 MHz clock to FLEXCOMM0 (debug console) */

CLOCK_AttachClk(BOARD_DEBUG_UART_CLK_ATTACH);

BOARD_InitBootPins();

BOARD_InitBootClocks();

BOARD_InitDebugConsole();

if (xTaskCreate(task1, "task1", configMINIMAL_STACK_SIZE + 50, NULL, hello_task_PRIORITY, NULL) !=

pdPASS)

{

PRINTF("Task creation failed!.\r\n");

while (1)

;

}

if (xTaskCreate(task2, "task2", configMINIMAL_STACK_SIZE + 100, NULL, hello_task_PRIORITY, NULL) !=

pdPASS)

{

PRINTF("Task creation failed!.\r\n");

while (1)

;

}

if (xTaskCreate(task3, "task3", configMINIMAL_STACK_SIZE + 160, NULL, hello_task_PRIORITY, NULL) !=

pdPASS)

{

PRINTF("Task creation failed!.\r\n");

while (1)

;

}

if (xTaskCreate(task4, "task4", configMINIMAL_STACK_SIZE + 161, NULL, hello_task_PRIORITY, NULL) !=

pdPASS)

{

PRINTF("Task creation failed!.\r\n");

while (1)

;

}

if (xTaskCreate(task5, "task5", configMINIMAL_STACK_SIZE + 170, NULL, hello_task_PRIORITY, NULL) !=

pdPASS)

{

PRINTF("Task creation failed!.\r\n");

while (1)

;

}

if (xTaskCreate(task6, "task6", configMINIMAL_STACK_SIZE + 200, NULL, hello_task_PRIORITY, NULL) !=

pdPASS)

{

PRINTF("Task creation failed!.\r\n");

while (1)

;

}

if (xTaskCreate(task7, "task7", configMINIMAL_STACK_SIZE + 300, NULL, hello_task_PRIORITY, NULL) !=

pdPASS)

{

PRINTF("Task creation failed!.\r\n");

while (1)

;

}

vTaskStartScheduler();

for (;;)

;

}

/*!

* @brief Task responsible for printing of "Hello world." message.

static void task1(void *pvParameters)

{

for (;;)

{

PRINTF("Hello world.\r\n");

vTaskSuspend(NULL);

}

static void task2(void *pvParameters)

{

for (;;)

{

PRINTF("H\r\n");

vTaskSuspend(NULL);

}

static void task3(void *pvParameters)

{

for (;;)

{

PRINTF("H\r\n");

vTaskSuspend(NULL);

}

static void task4(void *pvParameters)

{

for (;;)

{

PRINTF("H\r\n");

vTaskSuspend(NULL);

}

static void task5(void *pvParameters)

{

for (;;)

{

PRINTF("H\r\n");

vTaskSuspend(NULL);

}

static void task6(void *pvParameters)

{

for (;;)

{

PRINTF("H\r\n");

vTaskSuspend(NULL);

}

static void task7(void *pvParameters)

{

for (;;)

{

PRINTF("H\r\n");

vTaskSuspend(NULL);

}

Re: freeRTOS stack size configuration

Harry_Zhang — Fri, 08 Nov 2024 09:07:47 GMT

Hi @Relas

In FreeRTOS, the stack size specified in xTaskCreate() is measured in words (not bytes). For the LPC51U68, which uses a 32-bit word size, each word is 4 bytes.
For instance, if you specify configMINIMAL_STACK_SIZE + 50, this translates to (configMINIMAL_STACK_SIZE + 50) * 4 bytes of stack space.

The alignment adjustments by FreeRTOS or the compiler can cause discrepancies between the requested stack size and the actual allocated size.

Hang

MCUXpresso IDEのトピックfreeRTOS stack size configuration

freeRTOS stack size configuration

Re: freeRTOS stack size configuration