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The doorbot is responsible for scanning key fobs and unlocking the door for members. The software is written in Typescript and deployed to a Raspberry Pi. It expects to use the Wiegand protocol for reading fobs.

Implementation of the system is split up into a few repositories:

There are currently two doorbots. “Edd” takes care of the cleanroom doors, and “Hodor” is in the woodshop. These both check that keys are valid using “Tyrion”, the main server for the member database.

Building a Doorbot

A new doorbot can be built with the following components:

Doorbot Internal Layout

First, make the box by cutting the plywood on a laser cutter using this pattern: Run off all the 3D printed parts (power supply holders, Pi bracket, DB9 bracket). Install Raspbian to the SD card.

Using the brackets, screw down the power supply and Raspberry Pi, as well as the 5V power converter and the fan. The Pi should be placed near the open slot in the back, so you can plug in an Ethernet cable later.

Cut the end off the micro-USB cable, with enough length to run between the Pi and the 5V power converter. Connect the power wire (usually red) to the 5V output, and the ground (black) line to ground. Use hookup wire to connect the 12V output from the power supply to the input of the 5V converter, as well as the ground line.

Connect the 12V line of the molex connector (yellow wire) to the 12V power supply output, as well as the two central ground pins on the connector. Connect this to the fan.

Connect the hot/neutral/ground wires of the power supply to the plug. WARNING: These connections will be handling 120V power. Be sure they are well insulated and appropriately sized.

At this point, you should be able to plugin everything and have the Pi bootup.

DB9 Port

The DB9 port connects the box to the components being controlled. Although it should work as long as you connect up both sides the same, it's best if we keep all the doorbots in the shop the same. Here's the recommended pinout:

  1. +12V
  2. +5V
  3. Wiegand Data 0
  4. Wiegand Data 1
  5. GND
  6. GND
  7. Door Latch
  8. +5V
  9. GND

Wiegand Data 0 should go to the Rasbperry Pi's GPIO 12, and Data 1 should go to GPIO 13. Door Latch should go to the breakout board's MOSFET.

Raspberry Pi Breakout Board

Here's a wiring diagram for connecting the Pi:

Rasbperry Pi Hookup Schematic

Connect header pins on GPIO12 and 13, plus two for the door latch. You'll also want pins for an incoming 12V input and its ground. Add a few more pins for the 5V, 3.3V, and the Pi's ground.

Here's an example of a completed board:

Completed breakout board

This board has a few extras, like a jumper pin that could go to a switch, allowing power to be entirely cut to the latch (which might be useful for a magnetic hold system). There's also an LED indicator coming off an extra GPIO pin.

Installing the Software

The Raspberry Pi will need git and Node.js installed. The wiegand reader also needs the pigio library. Install typescript globally

$ sudo apt-get install nodejs git pigpio

$ sudo npm -g install typescript ts-node

Then, clone the deployment repository, branch “edd”:

$ git clone

$ cd bodgery-doorbot-deployment

$ git checkout edd

Install all the dependencies

$ npm install

Copy the systemd startup file, and set it to start at boot:

$ sudo cp rfid.service /etc/systemd/system/

To get the tight timings required, using a C program to read the Wiegand data tends to be more reliable than doing it in Typescript. So we'll install that:

$ git clone

$ cd wiegand_pigpio

$ make && sudo cp wiegand_c /usr/local/sbin/

The cache file should go in a tmpfs. Create the directory for this:

$ sudo mkdir /var/tmp-ramdisk

$ sudo chmod 777 /var/tmp-ramdisk

And add this line to /etc/fstab:

tmpfs /var/tmp-ramdisk tmpfs nodev,nosuid,size=100M 0 0

Install some dependencies for the cache update script:

$ sudo apt-get update

$ sudo apt-get install cpanminus

$ sudo cpanm Sereal::Decoder LWP::UserAgent Cpanel::JSON::XS LWP::Protocol::https

A username/password will need to be assigned to the box, which is created on the nginx frontend running on margery0. You should then set them at the top of

Add it to the crontab (with crontab -e):

1 * * * * perl /home/pi/doorbot/ > /dev/null

Which will update the cache file hourly.

Finally, start the whole thing running:

$ sudo systemctl start rfid

And have it start at boot:

$ sudo systemctl enable rfid

doorbot.txt · Last modified: 2022/05/29 16:01 by