.. zephyr:code-sample:: multi-thread-blinky
:name: Basic thread manipulation
:relevant-api: gpio_interface thread_apis
Spawn multiple threads that blink LEDs and print information to the console.
Overview
********
This example demonstrates spawning multiple threads using
:c:func:`K_THREAD_DEFINE`. It spawns three threads. Each thread is then defined
at compile time using K_THREAD_DEFINE.
The first two each control an LED. These LEDs, ``led0`` and ``led1``, have
loop control and timing logic controlled by separate functions.
- ``blink0()`` controls ``led0`` and has a 100ms sleep cycle
- ``blink1()`` controls ``led1`` and has a 1000ms sleep cycle
When either of these threads toggles its LED, it also pushes information into a
:ref:`FIFO <fifos_v2>` identifying the thread/LED and how many times it has
been toggled.
The third thread uses :c:func:`printk` to print the information added to the
FIFO to the device console.
Requirements
************
The board must have two LEDs connected via GPIO pins. These are called "User
LEDs" on many of Zephyr's :ref:`boards`. The LEDs must be configured using the
``led0`` and ``led1`` :ref:`devicetree <dt-guide>` aliases, usually in the
:ref:`BOARD.dts file <devicetree-in-out-files>`.
You will see one of these errors if you try to build this sample for an
unsupported board:
.. code-block:: none
Unsupported board: led0 devicetree alias is not defined
Unsupported board: led1 devicetree alias is not defined
Building
********
For example, to build this sample for :ref:`96b_carbon_board`:
.. zephyr-app-commands::
:zephyr-app: samples/basic/threads
:board: 96b_carbon
:goals: build flash
:compact:
Change ``96b_carbon`` appropriately for other supported boards.
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