ESP32 Interrupt Argument Passed Incorrectly

In this tutorial, you'll learn about ESP32 Interrupt Argument Passed Incorrectly. We cover key concepts, practical examples, and best practices.

The Problem

ESP32 interrupt callback receives wrong argument or NULL when a custom argument is passed.

Quick Fix

Wrong

int pin = 4;
gpio_isr_handler_add(4, myISR, &pin);  // pin goes out of scope

ISR receives dangling pointer. Reading it gives garbage values.

Right

// Use static or heap-allocated argument
static int pinNumber = 4;
gpio_isr_handler_add(pinNumber, myISR, &pinNumber);
void IRAM_ATTR myISR(void* arg) {
  int pin = *(int*)arg;
  if (pin == 4) {
    // Handle GPIO 4
  }
}

ISR receives correct pin number. GPIO 4 events handled properly.

Prevention

Ensure argument remains valid while ISR is active. Use static or heap-allocated memory. Pass structured data via pointer to struct. Do not pass stack-local variables. Use uint32_t value for simple integers.

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

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