ESP32 Firmware Debugging Guide

When to Use This Skill

Apply this skill when the user:

• Encounters compilation errors in ESP-IDF projects

• Sees runtime panics or "Guru Meditation Error" messages

• Has memory-related crashes or stack overflows

• Experiences I2C/SPI/UART communication failures

• Needs help interpreting serial monitor output

Debugging Techniques

1. Compilation Error Analysis

Missing Includes

fatal error: driver/gpio.h: No such file or directory

Fix: Check CMakeLists.txt and add the component to REQUIRES:

idf_component_register( SRCS "main.c" REQUIRES driver )

Undefined References

undefined reference to 'some_function'

Fix: Ensure the component containing the function is in REQUIRES or PRIV_REQUIRES.

Type Errors Look for mismatched types between function declarations and implementations.

2. Runtime Panic Analysis

Guru Meditation Error Patterns

Error Cause Fix

StoreProhibited

Writing to invalid memory Check pointer initialization

LoadProhibited

Reading from invalid memory Check null pointers

InstrFetchProhibited

Corrupted function pointer Check callback assignments

IntegerDivideByZero

Division by zero Add zero checks

Stack Overflow

Guru Meditation Error: Core 0 panic'ed (Stack overflow)

Fix: Increase stack size in task creation:

xTaskCreatePinnedToCore(task_fn, "name", 4096, NULL, 5, NULL, 0); // ^^^^ increase this

Stack Smashing

Stack smashing detected

Fix: Local buffer overflow - check array bounds and string operations.

3. Memory Debugging

Check Heap Usage

ESP_LOGI(TAG, "Free heap: %lu", esp_get_free_heap_size()); ESP_LOGI(TAG, "Min free heap: %lu", esp_get_minimum_free_heap_size());

Common Memory Issues

• Memory leak: Missing free() after malloc()

• Double free: Freeing same memory twice

• Use after free: Accessing freed memory

4. Communication Debugging

I2C Issues

E (1234) i2c: i2c_master_cmd_begin(xxx): I2C_NUM error

Checklist:

• Verify I2C address (7-bit vs 8-bit format)

• Check SDA/SCL GPIO pins

• Ensure pull-up resistors are present (4.7K typical)

• Verify clock frequency compatibility

Serial/UART Issues

• Baud rate mismatch

• TX/RX swapped

• Missing ground connection

5. Build Commands for Debugging

Clean build to eliminate stale objects

make robocar-clean && make robocar-build-main

Build with verbose output

cd packages/esp32-projects/robocar-main && idf.py build -v

Start serial monitor

make robocar-monitor-main PORT=/dev/cu.usbserial-0001

6. Useful ESP-IDF Config Options

Enable in sdkconfig or via idf.py menuconfig :

• CONFIG_ESP_SYSTEM_PANIC_PRINT_REBOOT

• Print panic info before reboot

• CONFIG_FREERTOS_WATCHPOINT_END_OF_STACK

• Detect stack overflow earlier

• CONFIG_HEAP_POISONING_COMPREHENSIVE

• Detect heap corruption

Examples

Example: Debugging a Stack Overflow

User reports: "My ESP32 keeps crashing on startup"

• Ask for serial monitor output

• Look for "Stack overflow" in panic message

• Identify which task is overflowing

• Suggest increasing stack size from 2048 to 4096

• Explain FreeRTOS stack sizing considerations

Example: I2C Communication Failure

User reports: "I2C device not responding"

• Verify address with I2C scanner

• Check GPIO configuration

• Verify pull-up resistors

• Check bus speed compatibility

• Suggest adding delays between transactions if needed