This is the documentation for the latest (master) development branch of Zephyr. If you are looking for the documentation of previous releases, use the drop-down menu on the left and select the desired version.

Blinky

Overview

Blinky is a simple application which blinks an LED forever using the GPIO API. The source code shows how to configure GPIO pins as outputs, then turn them on and off.

See PWM Blinky for a sample which uses the PWM API to blink an LED.

Requirements

You will see this error if you try to build Blinky for an unsupported board:

Unsupported board: led0 devicetree alias is not defined

The board must have an LED connected via a GPIO pin. These are called “User LEDs” on many of Zephyr’s Supported Boards. The LED must be configured using the led0 devicetree alias. This is usually done in the BOARD.dts file or a devicetree overlay.

Building and Running

Build and flash Blinky as follows, changing reel_board for your board:

west build -b reel_board samples/basic/blinky
west flash

After flashing, the LED starts to blink. Blinky does not print to the console.