#include "stm32f4xx.h"  // Adjust this include based on your Nucleo board series.

void delay(int count) {
    for (volatile int i = 0; i < count; i++);  // Simple delay loop.
}

int main() {
    // Enable GPIO clock (assumes LED is on Port A, Pin 5 for Nucleo-F401RE).
    RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN;

    // Configure PA5 as output.
    GPIOA->MODER &= ~GPIO_MODER_MODER5_Msk;   // Clear mode bits for PA5.
    GPIOA->MODER |= GPIO_MODER_MODER5_0;     // Set PA5 to general-purpose output.

    while (1) {
        GPIOA->ODR ^= GPIO_ODR_OD5;  // Toggle PA5.
        delay(1000000);              // Delay.
    }
}