Making your apartment lock smart with Bluetooth Low Energy(BLE)

During the times of Covid-19, its time to make a contact-less door opener

Background

During the corona crises, I decided to open the apartment door using my smart phone. I have documented in here, Github. It consisted of an esp8266 connected via Wifi to be connected to a cloud platform and a relay to drive the button. The problem with Wifi and electromechanical relays is that they are not power efficient.

Idea

The Bluetooth Low Energy(BLE) and transistors are comparatively energy efficient. So, I decided to upgrade the door lock opener with BLE.

The idea is to use a BLE based board to be able to still control it over the Internet/cloud. The smart phone sends a request via [cloud](blynk.io), the raspberry-pi acts as a gateway between cloud and the BLE device.

Reel Board

The reel board made by PHYTEC is equipped with an Epaper Display, environmental sensors, and Blue-tooth connectivity.

Security

To keep anyone from hacking away the BLE lock. The opening of the lock involved a challenge response. As soon as the central device connects to the peripheral, it can read the plain-text to which it must provide response after solving it.

Connected to the lock

Circuit Diagram with the Transistor

The circuit diagram can be found here [forum.iobroker.net](https://forum.iobroker.net/topic/7660/siedle-klingel-türöffner-mit-esp8266-und-mqtt/12) or [Here](https://forum.iobroker.net/assets/uploads/files/8530_schaltungt_.png)

Intercom wiring diagram

After looking at the multiple Internet forums to look for the wiring diagram for my intercom. I could only find a few links in German language. It pin-outs for the HTS-711 01.

Pin Name	Function
ERT	Signal to indicate a ring bell
7	Positive volts (12-24 VDC)
1	Negative or Ground
15	Monitor signal
16	Monitor signal

The voltage between the Pin-1 and Pin-7 range from 12-24 Volts DC but they have very limited current available ~ 15mA.

Blynk.io IoT Cloud

One need to install the andriod app from blynk.io. Inside the app, it provides some free credits to add different features inside the app. I added a button and a virtual blinking led. After creating the app, it sends the Auth-token needed inside the firmware. The firmware/sketch can be generated from the link below:

• Example code generator

TODO

• Update the source code from raspi and zypher

Weather info

The next step is to add weather support to be displayed over the e-ink display. To save the power the display only gets updated when someone is in-front of the reel board. The IR distance sensor on-board provides distance values.

Links and References and Acknowledgments

• Ejaad-Nama, a is newsletter. which cover different technology news. Please, subscribe here
• German Thread about the siedle intercom lock system [1]
• https://forum.iobroker.net/assets/uploads/files/1574673353705-siedle-spannungen-anmerkung-2019-11-18-100717.png
• On-line photo editor
• Draw.io
• https://pixabay.com/vectors/building-tall-housing-houses-48626/
• https://github.com/audef1/magicdooropener
• http://androidcontrol.blogspot.com/2015/05/arduino-wifi-control-with-esp8266-module.html
• https://forum.fritzing.org/t/lm2596-step-down-module/6380
• https://arduinomodules.info/ky-019-5v-relay-module/
• https://images-na.ssl-images-amazon.com/images/I/61kBdGlWCzL._SX679_.jpg
• This README template helped me alot to quickly write this document

The Next Step

Put the weather info over it

Buy me a toilet roll/hand sanitizers or a Mask. Else a coffee, if we are out of corona times ;)