Step 1: GPIO Input Handling and Debouncing
General-Purpose Input/Output (GPIO) Input Handling
GPIO input handling involves configuring microcontroller pins to detect and respond to digital signals from external sources such as switches, sensors, or buttons. When configured as inputs, GPIO pins read the logic level (HIGH or LOW) present on the pin, enabling the microcontroller to monitor external events and execute corresponding actions through software control.
Configure the GPIO pin for LED1 and EIC_EXTINT pin for mechanical switch (SW1) on the pin configuration.
Periodically check the pin’s state to determine if it is HIGH (logic 1) or LOW (logic 0).
Implement debouncing techniques to filter out noise or false triggers caused by mechanical switches, ensuring reliable signal detection.
Configure the pin to generate an interrupt when a change in state is detected, allowing for efficient event-driven programming.
Enable Debouncing to Prevent Multiple Transitions
When a mechanical switch is pressed or released, the signal does not transition cleanly from LOW (logic 0) to HIGH (logic 1), or vice versa. Instead, contact bounce may occur, causing the signal to oscillate rapidly between states before settling. This can result in multiple rising or falling edges, which may trigger several unwanted interrupts for a single press or release event.
To prevent these multiple transitions, debouncing must be enabled. Debouncing introduces a delay or filtering mechanism that ensures only a single stable signal transition is detected for each actuation of the mechanical switch. This process eliminates false triggers caused by contact bounce and provides more reliable input detection.
Debouncing on External Interrupt Controller (EIC)
The implementation of EIC-based debouncing streamlines the circuit design by eliminating the necessity for software-based debounce algorithms.