#Lighthome - Lightweight Home Automation

This repository contains part of my home automation configuration.

#Introduction

Though I'm using Home Assistant on the central server at the heart of my home automation (configuration here), I have various Raspberry Pis and other devices that are an integral part my home automation system.

To keep things on the various devices as lightweight and as portable as possible, I wrote 'lighthome'. It consists of various shell scripts and some simple programs to read/write several sensors. Central in the communication between all devices is the MQTT broker.

#Architecture

• scripts/common/include.sh - Defines common functions, including:
  • mqtt_receiver *[handlers]* - Subscribes to MQTT and registers one or more handler scripts, takes care of reconnect logic in case of failures, parallelisation, and runs asynchronously
  • mqtt_transmitter *[topic] [interval] [sender]* - Takes input and publishes it on MQTT, takes care of reconnect logic in case of failures, parallelisation, and runs asynchronously
  • mqttpub *[topic]* *[payload]*- Publish a single MQTT message
• handler scripts (scripts/mqtthandlers/*) - Receives MQTT stream on standard input and should invoke scripts that perform the action by calling an action script.
  • These scripts are sourced and everything inside should be run asynchronously!
  • The script doesn't have to deal with MQTT itself, except if it wants to publish feedback (using mqttpub)
• sender scripts (scripts/mqttsenders/*) - Monitors some device/sensor (preferably via an independent action script or program) and then translates its output for MQTT (standard output)
  • These scripts are run normally, either over and over at a specified interval or as a one-shot script that runs indefinitely by itself.
  • Standard output serves as payload for MQTT (the script doesn't have to deal with MQTT itself)
• actions scripts and programs (scripts/, programs/) - Perform any action, completely MQTT unaware, can also be invoked independently from command line for low-level testing
• setup-raspberry-pi.sh - Script to setup raspberry pi. For headless setup, first sudo touch /boot/ssh on the image, and add a /boot/userconf.txt with contents homeautomation:$encryptedpw where the password is encrypted with openssl passwd -6.

I decided on simple shell scripts to act as the glue between components and not opt for another layer in for example Python. In true UNIX-fashion each tool should have a well defined task, be efficient, communicate over standard input and output, and not add any unnecessary complexity. I also tried to separate the MQTT-logic from the logic addressing various sensors, so the latter can also be used independently.

The actual communication with MQTT is done via the excellent mosquitto CLI clients (mosquitto_sub and mosquitto_pub) communicating with the mosquitto daemon running on the main server.

#Devices

#Raspberry Pi 1 (RaspiOS)

• GPIO: 433.92Mhz Transmitter for lights (see also https://github.com/proycon/433mhzforrpi/)
• GPIO: Door/doorbell sensors (wired, reed contacts)
• GPIO: IR LED for remote control of TV/audio

#Raspberry Pi 2 (RaspiOS)

• GPIO: 433.92Mhz Transmitter for lights
• GPIO: Door/window sensors (wired, reed contacts)
• GPIO: Neopixels LED (WS2812B) for ambilight in living room
• GPIO: IR LED for remote control of TV/audio
• GPIO: IR Receiver
• USB: RFLink Transceiver, 433.92Mhz, based on Arduino Mega

#Raspberry Pi 3 (RaspiOS)

• GPIO: DHT-22 temperature/humidity sensor
• GPIO: Neopixels LED (WS2912B) fireplace (video)
• GPIO: PIR sensor
• GPIO: MH-Z19 CO2 sensor
• USB: RFLink Transceiver, 868.3Mhz, based on Arduino Mega

#Raspberry Pi 4 (RaspiOS)

• GPIO: Neopixels LED (WS2912B)

#History

Initially I ran Home Assistant on these devices as well, but due to their decision to remove GPIO support and the increased amount of unnecessary bloat which I don't need, I desired to go for a more lightweight approach and just write things from scratch.