How to Resolve Synchronization Issues in Multi-Threaded ESP32 FreeRTOS Application?
I am developing a multi-threaded ESP32 application using FreeRTOS to manage multiple sensor data streams (temperature, humidity, motion) and control signals. I face synchronization issues leading to race conditions and data corruption. Despite using mutexes and semaphores, the application behaves unpredictably under heavy load, with tasks occasionally accessing shared resources simultaneously, causing inconsistent data states and crashes. Specifically, I am seeing error messages like "Task watchdog got triggered" and "Guru Meditation Error: Core 0 panic'ed (LoadProhibited)" when tasks attempt to read sensor data concurrently. How can I diagnose and resolve these issues to maintain system reliability and performance?
Code:
// Example of using mutex for thread safety in FreeRTOS on ESP32
#include <freertos/FreeRTOS.h>
#include <freertos/task.h>
#include <freertos/semphr.h>
#include "driver/gpio.h"
#define SENSOR_PIN GPIO_NUM_4
SemaphoreHandle_t Mutex;
void sensorTask(void *pvParameters) {
while (true) {
// Acquire the mutex before accessing the sensor
if (xSemaphoreTake(Mutex, portMAX_DELAY) == pdTRUE) {
int sensorValue = gpio_get_level(SENSOR_PIN);
// Process the sensor value
xSemaphoreGive(Mutex); // Release the mutex
}
vTaskDelay(pdMS_TO_TICKS(100)); // Delay to simulate periodic task
}
}
void app_main() {
Mutex = xSemaphoreCreateMutex();
if (Mutex != NULL) {
xTaskCreate(sensorTask, "Sensor Task", 2048, NULL, 5, NULL);
}
}
6 Replies
Hi @Daniel kalu Try to double-check that mutexes and semaphores are correctly implemented and used consistently across all tasks accessing shared resources.
Also, ensure that the watchdog timer is not being triggered by long-running tasks. Use
vTaskDelay or taskYIELD to periodically yield control.So man , you having a tough time keeping your tasks in sync, even with mutexes
@Daniel kalu are you certain that the
mutex is always being released? If there's any condition where xSemaphoreGive() is not called, it could lead to the task watchdog being triggered.No, I realize now that there are some scenarios where SemaphoreGive) is not being called. Thank you for pointing this out. I will modify my code to ensure that the mutex is always properly released, even in exceptional circumstances.
Yeah, I was struggling to keep my tasks synchronized even with mutexes! I thought I was doing everything right, but I was missing something.