RTOS Concepts - Tasks, Scheduling, Priorities

/* FreeRTOS task creation — representative of most embedded RTOS APIs */
#include "FreeRTOS.h"
#include "task.h"

/* Task function signature: takes void* parameter, returns void, never returns */
void Task_CanReceive(void *pvParameters)
{
    (void)pvParameters;  /* suppress unused warning */

    CanFrame_t frame;
    for (;;)  /* tasks must run forever — never return */
    {
        /* Block until CAN frame available (puts task in BLOCKED state) */
        if (xQueueReceive(g_can_rx_queue, &frame, portMAX_DELAY) == pdTRUE) {
            Process_CanFrame(&frame);
        }
    }
    /* unreachable: vTaskDelete(NULL) here if task can legitimately end */
}

/* Task stack: statically allocated (required for ASIL — no heap) */
static StackType_t  s_can_rx_stack[512];  /* 512 × 4 bytes = 2 kB */
static StaticTask_t s_can_rx_tcb;

void App_Init(void)
{
    /* Create task with static allocation (deterministic; no malloc) */
    xTaskCreateStatic(
        Task_CanReceive,          /* function */
        "CanRx",                  /* name (debug) */
        512u,                     /* stack depth (words) */
        NULL,                     /* parameter */
        3u,                       /* priority (higher = more urgent) */
        s_can_rx_stack,           /* pre-allocated stack */
        &s_can_rx_tcb             /* pre-allocated TCB */
    );
}