Good news! It can! 🙂
It turns out the micro controller that is used (CS2105G0-S12) offers a nice pin (Pin 7 – I/O) to be used for external electronics. Conveniently the PCB has a test pad (T4) that one can solder to.
The layout shows how the Wemos D1 mini is powered. It runs MicroPython, only when the alarm goes off. An alarm must be active for about 20-30 seconds for a message to go through. The wifi module connects to a local wifi network and sends a MQTT message to a pre-defined channel.
The I/O-Pin 7 of the smoke detector is high at 9V when smoke is detected. The Mosfet will be switched on and the battery now powers the D1 mini as well, allowing notifications via network. The ESP8266 on the board is flashed with MicroPython. The script connects to the local wifi and notifies home-assistant via MQTT that smoke is detected. Home-Assistant does the rest.
I was looking for sensors that allow to monitor the status of a door. Typically those are magnet triggered switches that send some sort of signal when the magnet moves away and comes back. I wanted something based on Z-Wave. I’ve already light switch relays that are running on Z-Wave and am very happy with them. Z-Wave is on the pricier end of RF-devices. 433Mhz switches would be much cheaper, but Z-Wave offers nicer handling and hopefully more reliability.
Many of these sensors come in at around 40€. That is quite pricy so I opted for the cheap chinese solution at around 13.5€ per piece. You just have to be patient: 4+ weeks delivery time.
Setup into Home Assistant was straight forward. Add the device to the Z-Wave network via the web interface, rename it to mydoor… but then… How does the device report ‘door open’? The binary sensor that showed up, did nothing.
After some fiddling and searching I found that the sensor.mydoor_access_control changes it’s state rather unspectacularly from 23 to 22. It’s so inconspicuous that I didn’t notice the change the first few times I kept looking for changes.
Perfect! there is something we can use to integrate it to Home Assistant for automation and other stuff. Luckily there are templates that allow us to turn this into a binary sensor which is more useful in automations.
Add this to your configuration.yml:
The talk covers a simple example of a DIY sensor that runs MicroPython. Finally I give a short introduction to Home Assistant, a Python Home Automation Hub, that allows you to integrate with hundreds of devices. Home Assistant offers integrations to light switches, smart lights (Hue, Trådfri, Lightify,…), door sensors, heat control units, and many others.
There is a video of my talk on my Youtube channel:
I’ve been playing around with MicroPython and Home Assistant. MicroPython is a ‘bare-metal’-Python flavor that you can use to program ICs. Home Assistant is a home automation and home control software written in Python 3. It can be hosted on a Raspberry Pi. It enables you to connect a vast amount of different devices: lights, switches, sensors, locks etc.
This is a raw guide on how to make your own smart plug and connecting it to MQTT which is then connected to Home Assistant.
You will need a relay board (single relay), a NodeMCU board, a power adapter for 5V, a case, a button, some wire and a 1k resistor.
Connect the devices according to this schema (WARNING: Don’t do this if you’re not comfortable handling mains power!). Don’t forget earthing (it’s not on the diagram):
See the Home Assistant documentation for how to integrate the MQTT part with Home Assistant.
The nice thing is: you can press the button to switch the device. The status of the device will update via MQTT and Home Assistant gets a correct status update. You can of course switch the device from within Home Assistant as well.
I’ve been using the same old brushes for more than a year now on our “Profimaster Robot Model 2712”. They are a little misdesigned, as the brushes go under the wheels of the robot, which makes them tare. Continue reading Fixing brushes of the iRobot…→
One of the challenges with bitcoin is to store them securely. There have been severalwellknownincidentswhere Bitcoins have been stolen. It is no mystery. Bitcoin IS money! It’s the same with Euros or Dollars, when you have it lying around it will eventually be missing.
There is a twist with bitcoin to regular money. With Bitcoin one single piece ofinformationis enough for the thief to steal your Bitcoins: Your private key. With Bitcoin it’s about keeping this piece of information secret.
We wanted to paint one wall in our vestibule to add a little more color to the room. As we could not settle on a specific color, I thought of wallpaper. And is there any better theme than OpenStreetMap Data¹?
The theme was settled. It had to be a map, but which tiles? I thought of the beautiful pencil drawn MapBox tiles I saw some time ago:
We wanted some redish color so I had to convert the image with ImageMagick: