DevHeads IoT Integration Server•4mo ago

Resolving Deadlocks in ESP32 Robotic Arm Control with FreeRTOS

Hey guys i'm attempting on working on an ESP32 robotic arm control system using FreeRTOS and MQTT, but the system occasionally freezes. I suspect a deadlock between controlArmTask and sendCommandTask. These tasks manage critical arm control logic, including inverse kinematics,, and motor control.

void controlArmTask(void *pvParameter) {
  while (1) {
    xSemaphoreTake(mutex, portMAX_DELAY);
    // Control arm logic
    xSemaphoreGive(mutex);
    vTaskDelay(pdMS_TO_TICKS(1000));
  }
}

void sendCommandTask(void *pvParameter) {
  while (1) {
    xSemaphoreTake(mutex, portMAX_DELAY);
    // Send command logic
    xSemaphoreGive(mutex);
    vTaskDelay(pdMS_TO_TICKS(10000));
  }
}

void controlArmTask(void *pvParameter) {
  while (1) {
    xSemaphoreTake(mutex, portMAX_DELAY);
    // Control arm logic
    xSemaphoreGive(mutex);
    vTaskDelay(pdMS_TO_TICKS(1000));
  }
}

void sendCommandTask(void *pvParameter) {
  while (1) {
    xSemaphoreTake(mutex, portMAX_DELAY);
    // Send command logic
    xSemaphoreGive(mutex);
    vTaskDelay(pdMS_TO_TICKS(10000));
  }
}

The system randomly freezes and stops responding to troubleshoot, I reviewed the task code and mutex usage, monitored task states, checked for nested locks, and increased the stack size. I need help with Identifying and resolving deadlocks in ESP32 with FreeRTOS.

2 Replies

Joseph Ogbonna•4mo ago

Your system is likely freezing due to a deadlock between controlArmTask and sendCommandTask. To fix this: 1. Avoid Infinite Waits: Replace portMAX_DELAY with a timed wait, like pdMS_TO_TICKS(100), to prevent tasks from blocking indefinitely. 2. Check Task Priorities: Ensure task priorities are set properly to avoid priority inversion. 3. Avoid Nested Locks: Ensure that mutexes are not nested or locked in different orders by different tasks. These changes should help resolve the deadlock and prevent the system from freezing.

Marvee Amasi•4mo ago

You did a good job isolating the potential issue to controlArmTask and sendCommandTask , Use FreeRTOS built in debugging features or external tools to view you task states, the ownership of your mutex, and potential deadlocks. You might be holding the mutex for too long . Or use semaphores for synchronization instead

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Resolving Deadlocks in ESP32 Robotic Arm Control with FreeRTOS