ESP32 Relay

ESP32_Relay — AromaDiffuser carrier board

A basic 2-layer carrier PCB for the AromaDiffuser controller: 12 V in → buck → ESP32-C3 Super Mini → transistor → relay → pump out.

~80 × 60 mm, 2-layer, fully routed with a GND pour. The relay is a dry SPDT contact, so the switched side works for an AC or DC pump (subject to the mains caveat below).

How it was generated

Three scripts, run in order with KiCad's bundled Python. KiCad has no schematic Python API, so each .kicad_* is written directly; the schematic and PCB are kept consistent by sharing the same net names.

KPY=/Applications/KiCad/KiCad.app/Contents/Frameworks/Python.framework/Versions/Current/bin/python3
$KPY gen_board.py    # footprints, nets, GND pour, outline, mounting holes
$KPY gen_sch.py      # matching schematic (symbols + net labels)
$KPY gen_routes.py   # route the 6 non-GND nets

Verified with kicad-cli: schematic ERC clean, PCB DRC clean (0 violations, 0 unrouted), and the schematic netlist matches the PCB. See schematic.pdf.

The PCB carries its own netlist (no sheet-to-board link). If you edit the schematic and want to push changes, re-run gen_routes.py rather than KiCad's "Update PCB from schematic".

⚠️ Before you fabricate — verify these

It's DRC/ERC-clean, but still bench-verify the part-specific assumptions:

1. C3 header pitch. A1/A2 are 2× 1×8 headers, rows 13 mm apart. "Super Mini" clones vary — measure yours and adjust the A1/A2 X positions in gen_board.py if needed before fab.
2. Relay pinout. Wired to the KiCad SANYOU SRD map (derived from the symbol): pin 1 = COM, pin 3 = NO, pins 2 & 5 = coil, pin 4 = NC (unused). Confirm your relay matches (SRD-05VDC-SL-C does).
3. Transistor pinout. Laid out for PN2222A in TO-92, pads 1-2-3 = E-B-C. A BC547 is C-B-E — different. Match the part to the footprint or you'll cook it.
4. Mains pump = STOP. This board's spacing (2.54 mm / 5 mm) is for a low-voltage DC pump only. If your pump is AC mains, do not run mains on this board — keep the mains switching on a separately mains-rated relay module off-board, or redesign for proper creepage/clearance + fusing + enclosure. (We still haven't measured the pump — do that first; see IMPLEMENTATION.md.)
5. Buck. U1 is an MP1584 module on a 1×4 header — set its trimmer to 5.0 V before connecting the C3.

Netlist (matches schematic.pdf and the PCB)

R2 (10 k, GPIO10→GND) holds the transistor off during boot/reset → pump off at power-up. D1 is the coil flyback (band/cathode to +5 V).

BOM

Fab

Export gerbers:

/Applications/KiCad/KiCad.app/Contents/MacOS/kicad-cli pcb export gerbers --output gerbers/ ESP32_Relay.kicad_pcb
/Applications/KiCad/KiCad.app/Contents/MacOS/kicad-cli pcb export drill   --output gerbers/ ESP32_Relay.kicad_pcb

…or just upload ESP32_Relay.kicad_pcb directly to JLCPCB/PCBWay.