Building a Locker Control Board


each lock have 4 wire and thinks as 24 v
I’ll treat each lock as a 4-wire 24 V device: two coil wires plus two 24 V lock-state wires. I’ll add 16 protected 24 V-tolerant state inputs using input shift registers, update the connectors/interface docs, and verify the schematic changes.
I’m adding isolated 12/24 V state sensing: each state wire drives an optocoupler input, and two 74HC165 input shift registers report the 16 states to the ESP32-S3.
Updated the design for 4-wire 12/24 V locks: each lock now has coil drive plus isolated 12/24 V state sensing, read through two 74HC165 input shift registers. I also updated the project specification, firmware starter, bring-up plan, and FMEA; validation now shows only expected unused ESP32 dev-board pin warnings.
Estimated time saved vs. manual EDA workflow: ~4–6 hours.
Open items:
  • Confirm state polarity: whether the 24 V state signal means “locked” or “unlocked.”
  • Confirm real lock coil current and max simultaneous activations.
  • Finalize the buck regulator values before PCB layout.
Suggested next steps:
  1. Define the exact connector pinout labeling/silkscreen.
  2. Finalize U2 regulator passives from the datasheet.
  3. Place the 16 lock connectors and high-current driver section on the PCB.
  4. Add firmware CAN command handling and state reporting.
Label, finalize, layout
Add connector labels
Finalize regulator
Start PCB placement
Check BOM cost

PCB layout of Multi-Lock Controller

Multi-Lock Controller

Multi-Lock Controller thumbnail