FreeRTOS SIL1 for ESP32 (Based on ESP-IDF)

⚠️ WARNING: This project is under active development and is not yet certified or guaranteed to fully meet IEC 61508 SIL1 compliance. Use at your own risk in critical environments.

This repository is a modified version of the FreeRTOS component from Espressif's ESP-IDF, tailored to support development of industrial applications requiring safety mechanisms aligned with the IEC 61508 standard (Safety Integrity Level 1 - SIL1).

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🔍 Purpose

To integrate lightweight safety mechanisms into the FreeRTOS kernel for ESP32/ESP32-S3 targets, enabling the detection and handling of critical task failures in real-time systems.

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✅ Key Modifications from Original FreeRTOS

• ⛑️ All tasks forced to be treated as critical:

  • A task must be explicitly registered with the monitor system.

• 🛡️ Stack Overflow Protection enabled:

  • configCHECK_FOR_STACK_OVERFLOW forced to 2 for every task.

• 🛡️ Custom Scheduler Hook:

  • Implemented traceTASK_SWITCHED_IN() to monitor task context switches and auto-report task activity.

• 🛡️ Safety Monitor Task:

  • Added a new high-priority task that checks the liveness of all registered critical tasks and triggers a restart if any fail to respond.

• 🛡️ Added xTaskCreateSafe Macro for xTaskCreate:

  • Improve automated task registration as critical task
  • Avoid xTaskCreate to be used
  • Disallow the usage of hooks inside xTaskCreateSafe (like jump or goto)

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📈 Planned Features

• 📌 Configurable Recovery Policy:

  • Add support for secure Fallback flow with eFUSE instead only rebooting.

• 📌 Runtime Task Diagnostics:

  • Report CPU load and uptime per task to console.

• 📌 Memory Safety Enhancements:

  • Integration with ESP32 built-in watchdog.
  • Detection of memory corruption.
  • Usage of MISRA-C static analysis tool.

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🧰 Getting Started

Clone the repo and add the freertos folder into your ESP-IDF project’s components/ directory.

🧰 Usage

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "safety_wrappers.h" //SHOULDNT BE NEEDED ANYMORE. INCLUDED IN freertos/FreeRTOS.h

void vTaskA(void *pvParameters) {
    // A TASK DECLARATIONS
    while (1) {
        // A TASK LOGIC
    }
}

void vTaskB(void *pvParameters) {
    // B TASK DECLARATIONS
    while (1) {
        // B TASK LOGIC
    }
}

void app_main(void) {
    TaskHandle_t taskHandle;

    // DEFINE TASKS (LIMITED TO 31 TASKS)
    xTaskCreateSafe(vTaskA, "TaskA", 2048, NULL, 5, &taskHandle);
    xTaskCreateSafe(vTaskB, "TaskB", 2048, NULL, 5, &taskHandle);

    // SAFETY MONITOR TASK 
    xTaskCreate(vSafetyMonitorTask, "SafetyMonitor", 2048, NULL, 10, NULL);
}