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Bugs and Maintenance Tasks


  • a number of the tool controllers are crashing on a regular basis
  • on some of them there is evidence that this is caused by voltage spikes from motors, contactors or arc welding
  • this is plausible because most of the AC-DC power supplies are extremely cheap devices intended as LED drivers
  • we should try to find a better power supply module:
    • small enough to fit
    • good protection from transients
    • cheap enough that we can afford them
  • bought Mean Well IRM-03-5, hasn't helped
  • Class X suppression capacitors appear to fix the issue on Emco lathe and Juki sewing machine

Unreliable network connections:

  • some of the tool controllers have very poor connectivity
  • this might be related to power supplies (see above)
  • or maybe some of the ESP8266 devices are of poor quality
  • we should replace power supplies and/or deploy ESP32 devices

Tool controller PCBs: new tool controller PCBs are available and need to be assembled. There is one fully assembled and another three with SMD components only. Two more D1 Minis are required.


  • Tool Controller:
    • wiring diagram for a simple mains device
    • wiring diagram for an example of a no-volt switched device
  • Door Controller:
    • wiring diagram for a typical door

New demo door controllers (a completely assembled set of components to demo or test new firmware).

New tool controller enclosure: The existing plastic enclosures are no longer available for purchase. We will need to find a new box and design the mountings for future tool controller installations.

Door controller crashes:

  • “fast-flashing” crash: controllers sometimes freeze up in an unlocked state, with the LED in fast-flashing mode. This is a suspected race condition in the timers/scheduling used for the LED and buzzer. Not seen recently, may have been fixed by db3ee65.
  • “Fatal exception:28 flag:2 (Exception) epc1:0x40225c96 …”. Device self-restarts. Believed to be triggered by Android phone random UIDs and fixed by 46de766.

Migrate firmware config files to proper “/” prefix.

Purchase more PN532 NFC modules from and few of the new PN7150 for development. [ordered, in transit]

Device Issues

Emco Lathe:

  • controller regular crashes when motor is switch on or off
  • controller has been bypassed for now
  • easy to recreate (just turn the motor on/off a few times)
  • can still crash the controller when the current transformer is disconnect
  • unable to crash the controller when powered from an isolated battery pack
  • approx 300W
  • 2024-03-15: suppression capacitor fitted, appears to work
  • 2024-04-09: bypass removed


  • poor connectivity, repeated reconnects - fixed by channel change?
  • crashes when welder is in use
  • LCD sometimes shows corruption when welder is in use
  • 2024-04-13: suppression capacitor fitted to contactor, prevents crashing at power-off


  • poor connectivity, repeated reconnects - fixed by channel change?

Mitre saw:

  • poor connectivity, repeated reconnects
  • replacing the controller didn't help
  • 2024-03-21: replaced PSU with Mean Well, has not helped
  • 2024-03-24: firmware update failed repeatedly over 4 hours, device moved to G1 and it succeeded immediately, moved back to g8 and connectivity went bad again.
  • 2024-03-28: changing channel (11→6) on unifi-g8 has helped

Big laser cutter:

  • sometimes crashes when main contactor is de-energised, unable to recreate issue on demand
  • is it the contactor itself or one of the devices fed from it?
  • 2024-03-17: added ceramic 0.1uF and electrolytic 470uF 16V to 5V input of tool controller
  • 2024-03-21: added 0.1uF to contactor coil terminals


  • suspected crashes from motor on-off
  • was able to crash just from the contactor on-off
  • contactor has 0.1uF connected to output terminals
  • 2024-03-20: contactor 0.1uF moved to coil terminals, 0.47uF added about 6“ from motor, appears to work

Sewing machine:

  • suspected crashes from motor on-off
  • approx 800-900W
  • 2024-03-15: suppression capacitor fitted, appears to work

CNC router:

  • corrupted LCD
  • microcontroller crash and monitor blanks when contactor switches off
    • 2024-04-16: added capacitor to contactor coil

Future Projects

Migrate to ESP32

Existing ESP8266 firmware is stuck on an old SDK version due to a core library now being unsupported. The best way forward is to migrate to ESP32.

Tool controllers: v3 PCBs can take a Lolin S3 Mini microcontroller board. There is a test version of the firmware.

Door controllers: There is a new PCB design based on the ESP32-S3-WROOM-1, intended to fit in the existing enclosures. Firmware hasn't been ported yet.


Tim has toyed with a CircuitPython-based firmware. This would allow for easier development, potentially involvement of more people, and more advanced features (e.g. DESFire EV1 or PIV authentication support).

Backend Server

Allow standalone use with local files (no Django app required), for testing or for other installations. Support device configuration inheritance from multiple profiles. [done]

Open Source

It would be nice to package up the hardware and software to the point that other hackerspaces (or businesses) could use it.

Advanced NFC

Support high security (unclonable) tokens DESFire EV1, YubiKey PIV, FIDO2.

Rewrite Lockers

The tool lockers use a different architecture based around a secured MQTT server. It seemed like a good idea at the time.

If I rewrote it I would use something similar to the JSON message protocol from the door/tool controllers.

access_control.txt · Last modified: 2024-04-20 17:45 by tim

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