Pihat door

door

Door control system for the flipdot hackspace. It runs on a Raspberry Pi at the door together with a custom PCB in Raspberry Pi HAT form factor (pihat_door).

The current door control system is flipdot/flipdoor, a Rust project with web and SSH interfaces that serves door.flipdot.space. The Python implementation in this repository is legacy and no longer maintained. The sections below document that implementation and the hardware, which remain useful for reference.

The system:

• continuously reads the door state (open/closed) from a switch on the door
• unlocks/locks the door on request
  • from a web frontend (flipdot LDAP login, opening is restricted to flipdot members)
  • via RFID: members scan their card with a USB RFID reader
  • via MQTT close commands
• publishes the door state to api.flipdot.org, where it is displayed on the flipdot.org status page

Repository layout

The ldap_user/ and acme.sh/ submodules provide LDAP authentication and certificate handling respectively.

Hardware and serial protocol

The HAT carries a PIC16LF1719 that is wired to the Raspberry Pi GPIO header. It talks over a UART at 9600 baud 8N1 (config.SERIAL, default /dev/ttyAMA0).

The PIC continuously samples the door switch (ADC, averaged over 30 samples) and prints one line per batch:

<adc> - <ra0>\r\n

• <adc>: 10-bit average of the door switch reading; values > 500 mean the door is open
• <ra0>: digital input on pin RA0

Commands (single character, no newline required):

• 1 – pulse the door open (~200 ms)
• 0 – pulse the door closed (~200 ms)
• anything else – echoed back

The PIC sends b at startup and r (followed by a UART re-init) when it hits a UART over-error. door_lib.get_state() skips lines that do not start with a number, so these are handled transparently.

Web frontend

web.py is a small Flask app:

• login with flipdot LDAP credentials (ldap_user submodule)
• shows the current door state (10 s cache, or fake data when config.fake_door is set)
• "open door" button – only usable by flipdot members (is_member LDAP attribute)
• "close door" button

pip install -r requirements.txt
cp config.example.py config.py  # adjust DOMAIN, EMAIL, SERIAL, ...
./web.py

For production it runs under systemd (web.service) behind nginx (door-master.nginx.conf), which terminates TLS.

Set fake_door = True in config.py to run the app without the hardware.

MQTT and RFID

mqtt2door.py (run under systemd as mqtt2door.service) does three things:

1. Connects to the MQTT broker at power.flipdot.space:1883 and closes the door on the actor/door/close topic (plus a raw ESP sensor topic).
2. Polls the USB RFID reader on /dev/ttyUSB0. If the scanned tag is in rfid_tags.json, the door is opened, otherwise the event is only logged. sync_rfid_tags.sh regenerates rfid_tags.json from the employeeNumber attributes of all LDAP members, so member cards work automatically.
3. Publishes the door state to https://api.flipdot.org/sensors/door/locked/<0|1> every 60 seconds.

Firmware

door_firmware.X/ is an MPLAB X project for the PIC16LF1719 on the HAT (build with the XC8 compiler, e.g. via MPLAB X IDE). See hardware/pihat_door.pro for the board design.

Configuration

Copy config.example.py to config.py (git-ignored) and adjust: