System Utilities

Overview

Helpful utilities when debugging and tuning a system:

• vTaskList() — table of all tasks and states
• vTaskGetInfo() — details for a specific task
• uxQueueMessagesWaiting() — items currently in a queue
• xTaskGetCurrentTaskHandle() — handle of the running task

Enable stats formatting in FreeRTOSConfig.h:

#define configUSE_TRACE_FACILITY              1
#define configUSE_STATS_FORMATTING_FUNCTIONS  1

List All Tasks

#include "FreeRTOS.h"
#include "task.h"

void print_task_table(void){
  char buf[512];
  vTaskList(buf); // Name     State  Prio Stack Num
  uart_puts("Task           State Prio  Watermark\n");
  uart_puts(buf);
}

Tip

“Watermark” shows minimum remaining stack (higher is safer). If very low, increase that task’s stack.

Get Info for One Task

void dump_task(TaskHandle_t h){
  TaskStatus_t s;
  vTaskGetInfo(h, &s, pdTRUE /*include stack high watermark*/, eInvalid);
  // now s contains name, state, priority, watermark, etc.
}

Queue Backlog

#include "queue.h"
extern QueueHandle_t qSamples;

void monitor(void){
  UBaseType_t n = uxQueueMessagesWaiting(qSamples);
  if (n > 12) { uart_puts("Consumer falling behind!\n"); }
}

Current Task Handle

TaskHandle_t me = xTaskGetCurrentTaskHandle();
// e.g., self-suspend:
vTaskSuspend(me);

Notes

• vTaskList() and stats require enough buffer space and enabled config macros.
• Avoid calling these utilities in time-critical paths; use them for debugging and telemetry.