This is a simple project in which a HC-SR501 PIR sensor is used to detect motion in a room. MQTT is used as the message broke between NodeRed and Rust running on a Raspberry Pi 4. The code detects the presence and then notifies the server on a change in presence. Node Red then tells Alexa to turn the lights on and off within a time frame.
The architecture of the system is shown in the diagram below:
The Key parts are outlined below:
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Rust Presence Detector: Is a simple Script that uses polling to detect when the PIR Sensor is triggered. The PIR Sensor is configured for Repeatable Trigger Mode at. The code is constantly checking the pin every 5 seconds or so (This can be configured). At which point it sends an MQTT message on a state change.
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MQTT Broker Receives this message before forwarding it on to NodeRed as its subscribed to the same room topic.
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Node-Red Will then set its internal presence state before thend decided what to do. Based on the time of day the lights may come on or off depending on the state.
On the NodeRed side the following flow is used:
This flow will turn the lights in the master bedroom on and off dependent on the presence and the time of day.
Sadly the Alexa plugin for Node-red by applesstrudel is not working as expected. It seems to be a common issue with the plugin. I sadly had to abandon hopes of controlling my plusminus lightbulb and moved on to using a Matter controlled light bulb.
I have since moved to using a matter controlled light bulb. This is a much better solution as it is more reliable and does not require the use of a plugin. The light bulb is controlled using the Matter plugin.
Hardware wise, you must make sure the HC-SR501 is in Repeatable Trigger Mode and that the delay and sensitivity triggers are set accordingly.
Then configure your docker-compose.yaml file like how its configured in the example.
Then when you are ready run the docker compose command:
docker compose upIf you are developing with this project, I like to use the FT232H Breakout Board which provides desktop with GPIO, I2C and SPI connections. This can be done using the following command
cargo run --features=devThis will used the dev-config found here. You may also need to install the following dependencies for the FTD232H Board if you choose to work with it:
apt install libftdi1 libftdi1-dev
I started developing this on my Windows Machine using WSL2 and then slowly started pushing towards Raspberry Pi. Interestingly enough I found i had to share my FTD232H Device with WSL2 using the following commands:
ubbpid list
PS C:\WINDOWS\system32> usbipd list
Connected:
BUSID VID:PID DEVICE STATE
2-5 1bcf:2a02 Integrated Webcam Not shared
2-6 0403:6014 USB Serial Converter Attached
2-14 8087:0026 Intel(R) Wireless Bluetooth(R) Not shared
Persisted:
GUID DEVICE
# Share with WSL2
usbipd bind --busid 2-6
usbipd attach --wsl --busid 2-6Which then in Linux(WSL2) looks like so:
root@scott-Dev:/mnt/c/Users/scott-dev/OneDrive/Documents/Projects/HC-SR501-Node-Red-Presence-Detector# lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 0403:6014 Future Technology Devices International, Ltd FT232H Single HS USB-UART/FIFO IC
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hubWhen developing this code I wrote some simple MQTT code which could send and receive from the broker. It can be ran like the following:
cargo run --example mock_transmitter
cargo run --example receiver