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.