Building a Locker Control Board

flux

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.

flux

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
U1
U1 GPIO16 - U6 CP
U1 GPIO18 - U5 RXD
J2 4 - ISO1 C
J11 4 - Q17 C
Q17 C - R59 P1
L2 P2 - U2 FB
SW4 P1 - U1 GPIO0
Q19 C - R61 P1
R1 P2 - Q17 A
U1 GPIO11 - U3 SER
R49 P2 - ISO1 A
U1 GPIO17 - U5 TXD
R2 P2 - Q18 A
U1 GPIO15 - U6 ~PL
U7 Q7 - U6 DS
SW1 16 - U1 GPIO8
SW1 15 - U1 GPIO7
U1 GPIO14 - U3 ~OE
ISO1 C - R65 P1
U1 GPIO15 - U6 ~PL
U1 GPIO12 - U3 SRCLK
SW1 13 - U1 GPIO5
SW1 10 - U1 GPIO2
Q22 C - R64 P1
SW3 P1 - U1 GPIO21
SW1 14 - U1 GPIO6
SW1 9 - U1 GPIO1
Q20 C - R62 P1
Q17 C - R59 P1
L2 P2 - U2 FB
U1 GPIO16 - U6 CP
U1 GPIO10 - U6 Q7
Q23 C - R66 P1
SW1 12 - U1 GPIO4
U1 GPIO10 - U6 Q7
ISO1 C - R65 P1
U1 GPIO13 - U3 RCLK
SW1 11 - U1 GPIO3
Q18 C - R60 P1
Q21 C - R63 P1
Q18 C - R60 P1
ISO1 E - Q17 E
R37 P2 - R38 P2
U6 GND - U7 GND
ISO1 E - Q17 E
U6 GND - U7 GND
Q17
Q18
ISO1
U6
  • Generic Inductor
    Generic Inductor
    A generic fixed inductor suitable for rapid circuit topology development. The footprint automatically adapts based on the selected package, supporting standard SMD sizes (e.g., 0402, 0603, 0805) as well as well-known inductor packages such as SDR1806, PA4320, SRN6028, and SRR1260. Standard inductor values: 1.0 nH, 10 nH, 100 nH, 1.0 µH, 10 µH, 100 µH, 1.0 mH 1.2 nH, 12 nH, 120 nH, 1.2 µH, 12 µH, 120 µH, 1.2 mH 1.5 nH, 15 nH, 150 nH, 1.5 µH, 15 µH, 150 µH, 1.5 mH 1.8 nH, 18 nH, 180 nH, 1.8 µH, 18 µH, 180 µH, 1.8 mH 2.2 nH, 22 nH, 220 nH, 2.2 µH, 22 µH, 220 µH, 2.2 mH 2.7 nH, 27 nH, 270 nH, 2.7 µH, 27 µH, 270 µH, 2.7 mH 3.3 nH, 33 nH, 330 nH, 3.3 µH, 33 µH, 330 µH, 3.3 mH 3.9 nH, 39 nH, 390 nH, 3.9 µH, 39 µH, 390 µH, 3.9 mH 4.7 nH, 47 nH, 470 nH, 4.7 µH, 47 µH, 470 µH, 4.7 mH 5.6 nH, 56 nH, 560 nH, 5.6 µH, 56 µH, 560 µH, 5.6 mH 6.8 nH, 68 nH, 680 nH, 6.8 µH, 68 µH, 680 µH, 6.8 mH 8.2 nH, 82 nH, 820 nH, 8.2 µH, 82 µH, 820 µH, 8.2 mH #generics #CommonPartsLibrary
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  • Generic Resistor
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  • RMCF0805JT47K0
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Multi-Lock Controller

Multi-Lock Controller thumbnail
Functionally similar multi-channel electronic lock controller with 24 V lock outputs, 3.3 V logic, MCU control, shift-register expansion, CAN interface, test/reset controls, and protected solenoid driver stages.

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor

Qty 1

Arrow

$9.45–$12.30

Digi-Key

$19.94–$20.88

HQonline

$40.06–$41.87

LCSC

$62.10–$63.96

Mouser

$52.13–$52.85

TME

$1.14

Verical

$8.92–$22.52

Controls