Node API for Raspberry Pi GPIO pins

The goal of this little projects is to enable a Raspberry Pi to expose a simple web api to get and set the state of its GPIO pins. It is written in the Express library for Node.js

Setup for Development

• npm install
• npm start

If you want verbose output for debugging, run npm debug instead.

Setup and Deploy on a Raspberry Pi

• Assumes a default Raspberry Pi OS setup on the pi
• You need to install NPM and Node. Note that the Debian repositories that Raspberry Pi OS uses don't generally provide a very recent version of Node. You can sudo apt-get install npm and take whatever version it gives you, or follow a community guide to install a later version from a custom apt repository.
• Most of the source and documentation assumes that the project is cloned into /home/pi/.
• Double check that the index.js file in the root of the project and any scripts in the scripts/ directory of any uses cases you plan to use are executable.

Set up Service

A definition file is included to run the Node API as a Linux service. This way it will automatically recover from errors and will start automatically when the system boots up. This is nice in case the raspberry pi gets unplugged.

• To install the service you need to copy the nodeGpio.service file to /etc/systemd/system/. Please see the Raspbian documentation for more details.
• If the project was not cloned to /home/pi/Node-API-for-Raspberry-Pi-GPIO you will need to adjust the path (in two places) in the .service file)
• To stop, start or restart the service use the service command: sudo service nodeGpio restart
• To view the service logs use sudo journalctl -u nodeGpio

Set up cron

Cron jobs can combine very well with the service to automate whatever devices and tasks it is controlling. To edit the cron table, use crontab -e which will open a special editor. See the README file in src/useCases/outlet/ for an example cron setup.

Use cat /var/log/syslog | grep cron to see output from cron-related logs.

Scheduler

The api now includes a built-in schedule system. It is used by posting to /schedule with a number of minutes and an api path. The scheduler will recognize when the task is ready to run. There is a script in scripts/ called processSchedule that is meant to be combined with a cron job to run frequently (once a minute is good) to check for and process scheduled tasks.

* * * * * node /home/pi/Node-API-for-Raspberry-Pi-GPIO/scripts/processSchedule.js