.. _blink-led-sample:
PWM: Blink LED
##############
Overview
********
This is a sample app which blinks a LED using PWM.
The LED will start at a blinking frequency of 1 Hz. Every 4 seconds,
the blinking frequency will double. When the blinking frequency
reaches 64 Hz, the blinking frequency will be halved every 4 seconds
until the blinking frequency reaches 1 Hz. This completes a whole
blinking cycle. This faster-then-slower LED blinking cycle repeats forever.
Wiring
******
Arduino 101 and Quark D2000 CRB
===============================
You will need to connect the LED to ground and PWM0 via the shield.
You may need a current limiting resistor. See your LED datasheet.
Nucleo_F401RE, Nucleo_L476RG, and STM32F4_DISCOVERY
===================================================
Connect PWM2(PA0) to LED
Nucleo_F103RB
=============
Connect PWM1(PA8) to LED
Hexiwear K64
============
No special board setup is necessary because there is an on-board RGB LED
connected to the K64 PWM.
nRF52840_PCA10056
=================
No special board setup is necessary because there is an on-board LED connected.
Building and Running
********************
This sample can be built for multiple boards, in this example we will build it
for the arduino_101 board:
.. zephyr-app-commands::
:zephyr-app: samples/basic/blink_led
:board: arduino_101
:goals: build flash
:compact:
After flashing the image to the board, the user LED on the board should start to
blinking as discussed in overview
ff9c20826c