Project:Tool Access Control

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Hackspace has a couple of dangerous/expensive bits of equipment which we need to control access to, both for safety reasons and to stop untrained people damaging them. At present this is done by sharing locations of keys, but this is not very hacker-like.

A solution is a control device consisting of a box which enables the machine for as long as your RFID card is in the box. This can also act as an automatic electronic logbook for the device.

The Hackspace will agree to buy at least 3 of these and will pay a reasonable premium to someone who can design, build and test them. This sounds like it could be a nifty commercial project with relatively few modifications.

Functional Specs

  • Relay contacts of at least 10 amps for switching the device. Hard-wired in using suitable grommets and with sufficient isolation between low and high voltage.
  • HF RFID reader
  • Internal database of (up to at least 1000) authorised RFID card IDs, plus a flexible way of fetching updates from the membership server.
  • Ethernet connectivity (could be powered through PoE).
  • Logging of who used the machine + hours used.
  • Open Source hardware & software.


  • Ideally sub-£60.
  • Ability for super-users to program new cards from the device - this should result in a callback to the membership server to verify it.
  • Easy to program/modify (i.e. Linux instead of microcontroller code).
  • Ability to monitor "actual" hours run - i.e. how long the laser cutter tube is actually on for. (This could potentially be done using a current transformer sensor.)
  • Ability to poll for current state over the network.
  • Broadcast events on the network like doorbot.

Potential design

  • Dual-USB Bifferboard (£45), Touchatag reader (£27)
  • Single USB bifferboard (£35), Cheap chinese RFID reader (£18, serial)
  • One of the more fancy STM32s or other SOCs might be able to drive costs down further.