The Sizaha IoT (Internet of Things) platform is composed of three fundamental moving pieces:
- Raspberry Pi device
- Cloud
- Mobile Application
There are many different daemons and scripts on the Raspberry Pi Zero W device that run based on the state of the device. There are 3 different possible states of the device:
- Factory
- Test Config
- Configured
When the device is in its configured state (meaning that it successfully completed its bootstrapping), GarageDaemon controls the Raspberry Pi Zero's GPIO output on pin 23.
When given the proper instruction, GarageDaemon signals to the optical coupling relay switch to close the circuit, which is what triggers the garage into either opening, closing, or stopping (same as if you pressed the physical garage door button).
Scripts are written in Shell and Python (using Flask).
The Google Cloud + Firebase component of the Sizaha platform is composed of four different services:
- API Server
- Firestore (database)
- PubSub
- Firebase authentication
The API server is a business-specific service that I created and serves the purpose of registering devices, getting the list of a user's devices, making sure the user gets the proper device and not others, and to send the command to open the garage. The API server (api.sizaha.com) runs in the cloud, and tells the PubSub or the Firestore what to do. The mobile application sends HTTP messages to the API server that either retrieve or send a chunk of JSON data. The API server is written in Python using Flask.
The Firestore is the database where the data is saved. This is where a track record of 'who owns what' is kept. It stores all the data related to the Sizaha business.
PubSub is a message queue service between the website/mobile application, and the Raspberry Pi device. The app/website delivers a message to the API server, which sends the message to the PubSub, which pushes the message to the device. Instead of having the device asking for HTTP GET requests constantly all the time, the PubSub pushes messages to the respectice device. Based on the topic and the subscription of the message, it figures out which device to route the message to.
Firebase Authentication is a service Sizaha uses as an identity provider. This means that a user must log in with either their Google, Twitter, or Facebook accounts in order to use the application. The Firebase authentication service is used so that I didn't have to invent my own user management system.
The mobile application is the client-side of the of the platform. It allows the user to activate the garage door, connect to the Raspberry Pi device during the bootstrapping process, and other user actions.
