gpiozero-toggle-led

Example using js-gpiozero library to toggle internal activity LED on the Raspberry Pi Zero W.

Note that the "zero" in gpiozero doesn't imply the Raspberry Pi Zero (although that's the platform I developed this on). It's related to the original gpiozero Python library which has now been ported in JavaScript as js-gpiozero.

Installation

Here, I'm assuming that your Raspberry Pi Zero W is named pizero but that might not be the case. Make sure to update for your Pi's hostname below.

First make sure that your Raspberry Pi Zero is up-to-date.

$ ssh [email protected]
$ sudo apt-get update

Next, make sure that you have the latest version of Node for the Raspbian distribution. Note that this will be different for a Raspberry Pi 3 and you shouldn't run this.

$ cd ~
$ wget https://nodejs.org/dist/v6.10.3/node-v6.10.3-linux-armv6l.tar.xz
$ tar -xJf node-v6.10.3-linux-armv6l.tar.xz
$ cd node-v6.10.3-linux-armv6l
$ ./bin/node -v
v6.10.3
$ sudo cp -R * /usr/local
$ node -v
v6.10.3
$ npm -v
3.10.10

Now you're ready to pull the code and run it, noting that it takes root privileges to talk to the GPIO pins so npm start has to run via sudo.

# This command will temporarily turn off the
# standard behavior for the built-in activity
# LED on the Raspberry Pi. This will revert back
# to normal upon reboot.
$ echo none | sudo tee /sys/class/leds/led0/trigger
$ ssh [email protected]
$ cd ~
$ mkdir sites
$ cd sites
$ git clone https://github.com/OutsourcedGuru/gpiozero-toggle-led.git
$ cd gpiozero-toggle-led
$ npm install
$ sudo DEBUG=gpiozero-toggle-led:* npm start
# You can do this from your own workstation
# with a browser if you'd like
$ open http://pizero.local:3000

Exercising the code

The Express-generated website is very simple. The main index page (HTTP GET) exercises the js-gpiozero library to blink the built-in activity light on the Raspberry Pi Zero. It presents a button which will post back to the same page. On HTTP POST it will run a different function in the routes file to toggle off the same LED.

Note that the interface level of a Raspberry Pi Zero is reversed from that of a Raspberry Pi 3. So the call to gpio.LED(pin, false) has a second argument which must be called for it to work as expected.

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