A custom HomeKit accessory with Python

Hi πŸ‘‹,

In this short article I want to showcase how I implemented a custom HomeKit accessory with python.

My Home Assistant’s SD card died πŸͺ¦ a few days ago and the support for GPIO based sensors will be removed in newer releases. This makes it unsuitable for my needs, while giving me the perfect opportunity to try other things.

To continue monitoring temperature and humidity in my home I’ve built a custom HomeKit accessory with HAP Python.

The Sensor

A BME680 air quality sensor is used to monitor temperature and humidity. It is connected to the PI according to the following diagram:

The communication with the Pi is done using the I2C protocol. If you want to use I2C in your own setup, it has to be enabled using raspi-config, as it doesn’t come enabled by default.

# Execute
sudo raspi-config
# Then select Interfacing options->I2C and enable it.

Connection can be tested with the following command:

sudo apt-get install build-essential libi2c-dev i2c-tools python-dev libffi-dev git
/usr/sbin/i2cdetect -y 1
pi@raspberrypi:~ $ i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- 76 -- 

It will output the address that the sensor is using, in our case the 0x76 I2C address.

The Code for the Accessory

You can browse the full code for the accessory and bme680 sensor in my git repo.

To run the program, clone the repository and ensure that you’re running it under the pi user, otherwise you will need to change some things.

cd /home/pi && git clone git@github.com:dnutiu/bme680-homekit.git && cd bme680-homekit
sudo apt-get install libavahi-compat-libdnssd-dev
pip3 install -r requirements.txt

Verify that the program works by running python3 main.py. Running it the first time will prompt you to add the accessory to the Home app. If you miss this step you can repeat it by deleting the accessory.state file located in pi’s home directory and by running the program again.

After you’ve verified that it works, you can setup a systemd service to run the accessory’s python script when the PI boots

Copy the bme680-homekit.service to /etc/systemd/system and check that the service is running.

sudo cp bme680-homekit.service /etc/systemd/system
sudo systemctl status bme680-homekit

If you want to run this under another user rather than the pi, you’ll need to tweak the bme680-homekit.service file.

Congratulations for making it this far! πŸŽ‰

You can browse more code examples in the HAP-Python repository.

Thanks for reading and have fun! πŸ‘©β€πŸ’»πŸ‘¨β€πŸ’» βš™οΈ

How to connect Ethernet devices to WiFi via WDS

Hi πŸ‘‹,

In this blog post I will show you how to connect an Ethernet only device to Wi-Fi using an extra router and the WDS functionality. I initially wanted to install the TP Link Archer T4U WiFi adapter driver on my Ubuntu 20.04 PC but unfortunately the driver is no longer supported.

Since I really needed high internet speed for my PC, I decided to connect it via an Ethernet cable and buy another TP-Link router to use in WDS mode.

WDS mode allows routers to communicate with one another without using wires.

βš™οΈ The configuration of the WDS router is as follows. I left the operation mode in Router Mode.

Then, I navigated to Network -> LAN and set the IP address to 192.168.0.2. Because my old router had the IP address of 192.168.0.1.

The next step would be to navigate to Wireless -> WDS. Click survey and select the SSID of your root router. If the WDS bridging is successfully you should see a Connected message βœ….

Finally, go to Network -> DHCP Server and disable it. All these operations should be performed on the router that you want to bridge, not the root router! πŸ•ΈοΈ

Now that your router has a WDS bridge to the root router, you can connect your PC to it via an Ethernet cable and place it next to your PC. A brand new 5GHz Wi-Fi adapter might have the same price πŸ’° as a new router πŸ€‘, and to be honest unless you’re doing some penetration testing I don’t see the need of a WiFi adapter.

Thanks for reading and happy hacking! 🐧

How to make RØDE audio interface work on Linux

Hi πŸ‘‹,

I have recently updated the firmware of my RØDE audio interface from 1.12.x to 1.13, and the device was no longer working properly on Linux. I found out that it was an audio sampling issue.

dmesg -kH

[feb21 16:20] usb 1-9.3: 1:1: cannot set freq 44100 to ep 0x82
[  +0,005008] usb 1-9.3: 1:1: cannot set freq 44100 to ep 0x82
[  +0,005019] usb 1-9.3: 1:1: cannot set freq 44100 to ep 0x82
[  +0,004971] usb 1-9.3: 1:1: cannot set freq 44100 to ep 0x82
[  +0,015019] usb 1-9.3: 1:1: cannot set freq 44100 to ep 0x82

To fix it, I did the following:

1. Edit Pulse’s πŸ“– daemon.conf.

nano /etc/pulse/daemon.conf

And add the following lines:

default-sample-format = s24le
default-sample-rate = 48000
alternate-sample-rate = 48000

2. Disconnect the device and then kill the pulse daemon with πŸ”ͺ pulseaudio -k.

3. Connect back the device πŸ”Œ, it should work without problems.

Thanks for reading and happy hacking! πŸ₯·

Home automation with Home Assistant on Raspberry PI – Getting Started

Hi πŸ‘‹

The purpose of this article is to get you started quickly with a Home Assistant on a Raspberry Pi. It’s a simple walkthrough on how to install Home Assistant and configure it so it will boot with your PI.

I will use my old Raspberry PI V3 board.

Flashing the Raspberry PI OS

You will need a microSD card of reasonable size, I’m using a 16GB one and a USB Adapter to connect it with my PC.

Head over to Raspberry Pi OS website and download your preferred image, for my Home Assistant I’ve chosen Raspberry Pi OS with desktop and recommended software. After the download is completed, unzip the file and prepare to flash it.

To flash the OS image on the SD card I will use a program called balenaEtcher.

Download it, select your OS image, select the SD card, and hit flash.

After SD card flashing finishes, it is time to setup the Wi-Fi connection. If you’re using an ethernet cable you can skip this step, however, remember to enable SSH.

Setting up the Wi-Fi and enabling SSH

Unplug the SD card from the computer and plug it back. You should see two new drives D: and E:

  1. Open your favorite text editor and create an empty file called ssh in drive E:. This will enable SSH access.
  2. Create a new file called wpa_supplicant.conf using your text editor and paste the following contents in it:
country=us
update_config=1
ctrl_interface=/var/run/wpa_supplicant

network={
   scan_ssid=1
   ssid="YOUR_WIFI_SSID"
   psk="YOUR_WIFI_PASSWORD"
}

Don’t forget to replace YOUR_WIFI_SSID and YOUR_WIFI_PASSWORD with the corresponding values regarding your Wi-Fi network.

Eject the SD card from your computer and plug it into the PI. At boot, the PI should automatically connect to your Wi-Fi network.

Installing Home Assistant Core

Find your Raspberry PI’s IP address and connect to it via ssh. You can run the command ssh pi@192.168.0.XXX. The password for the pi user should be raspberry.

After getting a shell, follow the instructions for installing Home Assistant from the official website.

Ensure that you run each command on its own line. Don’t directly copy the entire code block, copy each line individually.

Starting Home Assistant on boot

If you can access the Home Assistant web GUI using http://192.168.0.XXX:8123 then the next step would be to create a new systemd service so that some assistant starts at boot. Please replace XXX with your Raspberry PI’s IP address.

To create a new service:

  1. Start a new shell on the Raspberry or ensure that you’re using the pi user. We will execute commands with sudo.
  2. Use sudo nano /etc/systemd/system/hass.service to create a new file and paste the following contents into it:
[Unit]
Description=HomeAssistant Service
After=network.target

[Service]
User=homeassistant
WorkingDirectory=/home/homeassistant
Environment="PATH=$PATH:/srv/homeassistant/bin"
ExecStart=/srv/homeassistant/bin/hass

[Install]
WantedBy=multi-user.target

Stop hass command if it’s running and enables the service by executing:

sudo systemctl start hass.service
sudo systemctl enable hass.service
sudo systemctl status hass.service

If the service is running normally, everything is set up. You can safely reboot your PI and the Home Assistant service will run after boot.

Configuring Home Assistant

When visiting the Home Assistant’s web interface for the first time, you will be prompted to create a new user. You may also download the Home Assistant application for your mobile device if you wish to track things like battery, storage, steps, location and so on, in Home Assistant.

In future articles I will show you how to configure the BME680 enviromental sensor and how to activate the Apple Homekit integration. Until then, have fun exploring Home Assistant docs.

Things to do further:

Unattended Upgrades – Enable unattended upgrades for your Raspbian OS. Ensures that your OS’s is always patched and up to date.

UFW – Secure your Home Assistant server with the uncomplicated firewall.

Change default passwords or disable SSH login via password.

Thanks for reading and happy automations! πŸ“š