4. GPIO (using LED and Push Button)

    I this example we are using Green LED on our stem32f4 Discovery Board. It will turn on, once the
    push Button is pressed.

    Steps:
    1. Enable clock for LED:
        RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
    2. Enable clock for push Button:
        RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    3. Configure Pins (LED and push Button)
    4. We can then use the LED and Button

    Example:

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