Button demo

Overview

A simple button demo showcasing the use of GPIO input with interrupts.

Requirements

The demo assumes that a push button is connected to one of GPIO lines. The sample code is configured to work on boards with user defined buttons and that have defined the SW0_* variables.

To use this sample, you will require a board that defines the user switch in its header file. The board.h must define the following variables:

  • SW0_GPIO_NAME (or DT_ALIAS_SW0_GPIOS_CONTROLLER)
  • DT_ALIAS_SW0_GPIOS_PIN

Alternatively, this could also be done by defining ‘sw0’ alias in the board devicetree description file.

Building and Running

This sample can be built for multiple boards, in this example we will build it for the nucleo_f103rb board:

west build -b nucleo_f103rb samples/basic/button

After startup, the program looks up a predefined GPIO device, and configures the pin in input mode, enabling interrupt generation on falling edge. During each iteration of the main loop, the state of GPIO line is monitored and printed to the serial console. When the input button gets pressed, the interrupt handler will print an information about this event along with its timestamp.