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Door Access Controllers


The Hacklab door controllers are based on an ESP8266 wifi microcontroller and a PN532 NFC reader module. One controller is installed for each door, and each controller can operate a single 12V channel for an electric door release or magnetic lock. Inputs can be connected for door open/closed reed switch, exit request and local lock/unlock “snib” function.


Reference Component Farnell
C1 1206 10uF 25V 2320887
C2 1206 22uF 6.3V 2320911
C3, C4 0603 0.1uF 6.3V 1759016
D1 SMA diode B230A 1843686
D2 SMA diode (flyback protection) 1625280
JP1 PCB male header 2.54mm pitch 3-way
JP2 PCB male header 2.54mm pitch 2-way
L1 Coilcraft LPS6225-472MRB 4.7uH 2A 2408256
P1, P2, P3 PCB screw terminals 5.08mm pitch 2-way (9 total)
P4 PCB male header 2.54mm pitch 6-way
Q1, Q2 MOSFET-N SOT-23 2069541
R1 0603 31K6 1% 2059454
R3 0603 56K 1% 2303215
R2, R4 0603 10K2 1% 2059407
R5, R6, R7, R9, R10, R11 0603 10K 1% 2303192
R8 0603 2K2 1% 2303166
SW1 EVQPT5 tactile switch 2425617
U1 ADP2301
U2 SRD 12V relay
U3 ESP-12E

Errata: a generic through-hole flyback diode should be fitted between GND and 12V_OUT, on the underside of the screw terminal.

Lessons Learned

Future PCB revisions are likely to be based on a Wemos D1 Mini module to reduce component count and allow easier debugging. The onboard DC-DC converter will be replaced with an off-the-shelf “LDO replacement” DC-DC converter module.

Controller Unit


The laser-cut mounting plate is designed to hold the PCB secure at the back of the enclosure. Attach the PCB with M3 nylon bolts and nylon or metal nuts (the nut should go above the board to minimise the space used below the mounting plate).

The mounting plate should secure itself reasonably well with a push-fit, but consider adding a rubber foot or a blob of hot-melt glue to prevent it from rocking.

Drill a large hole in the side of the enclosure for wiring. Drill screw holes for wall-mounting. Drill two holes in the enclosure lid for the LED and push-button.

The push-button and LED may be wired as two separate pairs, or with a shared GND. The LED should have a 120R series resistor.

Connect the reader cable to the 8-way screw terminals. The controller push-button should be connected to the GND/SNIB pair of terminals. The controller LED should be connected to GND and LED (shared with the reader).

Take care to keep wiring away from the antenna.

Reader Unit

CAD files: DWG DXF

Circuit diagram: PDF


  • 3mm blue LED
  • 120R resistor (this is low, but an additional resistor is used on the controller PCB)
  • Alarm cable with at least 7 cores (Cat5 can be used but is not recommended)

The reader enclosure is formed from three layers of 3mm black acrylic. The layers should be joined with cyanoacrylate adhesive.

Configure the PN532 module to use I2C communications.

Bend and cut the LED leads to the correct shape and length. Solder the LED and cable before gluing the module into the enclosure.

Cable colours in Hacklab installations:

Pin G1/G2/G8 G11 (and photos)
GND blue blue
VCC green orange
RST brown brown
SDA orange green
SCL white-green white-green
LED +ve white-brown white-brown
Piezo white-blue white-blue

The LED should be connected between LED and GND, with a 120R series resistor. To avoid damaging the LED, use hot-melt glue to secure it in place (not cyanoacrylate).

The piezo should be connected between PIEZO and VCC (green). The piezo may be secured with cyanoacrylate or hot-melt glue, but try to give the disc some freedom of movement or the sound output may be reduced.

Test the reader and controller together before securing the reader to the wall with double-sided adhesive foam tape.


Two versions of firmware and server back-end are currently in operation.

Common features:

  • Ability to read any 13.54MHz ISO-14443 Type A token including MIFARE Classic/UltraLight and NFC tags.
  • Network-based checking of tokens with fallback to syncronised on-board database.
  • Detection of door open/closed state via reed switch.
  • Exit request handling, either opening for a set time or opening as long as in input is held (for our capacitive-touch door handle).
  • “Snib” feature to hold the door unlocked for an extended period, with automatic timeout.
  • Remote enable/disable of exit request for additional security.
  • Remote enable/disable/renewal/timeout of snib state to allow presence detection to trigger timeout of snib state.
  • Input DC voltage measurement, using low voltage as an indication of battery backup during a power outage. Snib feature can be disabled during power outage to extend battery life (for fail-secure locks).

Legacy/Stable: The older version uses UDP networking and requires a dedicated wifi network for security. All of the Hacklab doors use this version at the time of writing.

New: A new firmware and back-end use TLS-enabled TCP networking, so do not require a special wifi network. The modern codebase is better-written, more flexible and features OTA upgrades.

door_access_controllers.txt · Last modified: 2019-04-29 17:50 by tim