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.

Building and Running

This sample can be built for multiple boards, in this example we will build it for the arduino_101 board:

# On Linux/macOS
cd $ZEPHYR_BASE/samples/basic/blink_led
mkdir build && cd build
# On Windows
cd %ZEPHYR_BASE%\samples\basic\blink_led
mkdir build & cd build
cmake -GNinja -DBOARD=arduino_101 ..
ninja
ninja flash

After flashing the image to the board, the user LED on the board should start to blinking as discussed in overview