ESP32 Log Format Produces Garbled Output

In this tutorial, you'll learn about ESP32 Log Format Produces Garbled Output. We cover key concepts, practical examples, and best practices.

The Problem

ESP32 log messages have garbled formatting, missing arguments, or incorrect type display.

Quick Fix

Wrong

ESP_LOGI(TAG, "Value: %d
", 22.5);  // Wrong format specifier

Value: 1234567890
(Garbage from format mismatch)

Right

int intVal = 42;
float floatVal = 22.5;
char* strVal = "hello";
ESP_LOGI(TAG, "int=%d float=%.1f str=%s", intVal, floatVal, strVal);
ESP_LOG_BUFFER_HEX(TAG, data, 16);  // Hex dump buffer

I (123) tag: int=42 float=22.5 str=hello
I (124) tag: 7C 9E BD 45 12 78 00 00 00 00 00 00 00 00 00 00

Prevention

Use correct format specifiers: %d for int, %f for float, %s for string, %p for pointer, %x for hex. Use ESP_LOG_BUFFER_HEX for binary data display. Do not add \n at end (added automatically).

DodaTech engineers apply these same patterns across Doda Browser, DodaZIP, and Durga Antivirus Pro for production IoT reliability.

FAQ