Morsekey shield

MorseKey shield (v2)

A snap-on shield for the Waveshare ESP32-S3-LCD-1.47B with the same footprint as the board itself (36.37 × 20.32 mm): one 3.5mm jack that serves both an iambic paddle (TRS plug) and a straight key (TS mono plug — the firmware auto-detects it), an optional piezo sidetone, and female headers the ESP32 board (male pins soldered pointing down) plugs into.

The jack opens at the antenna end, its bushing protruding past the edge the same way the USB-C does at the other end. Renders: render-top.png / render-bottom.png.

Ordering (JLCPCB, PCBWay, OSH Park…)

Upload morsekey-shield-gerbers.zip to the fab's quote page. All defaults are fine: 2 layers, 1.6 mm FR-4, HASL, any color, smallest quantity (usually 5). Cost is a few dollars plus shipping.

Before ordering — the paper test: print placement-1to1.pdf at 100% scale (no "fit to page"), hold the ESP32 board's header holes over the drawing, and confirm every hole lines up. This catches any dimension error while it's still free.

Bill of materials

Piezo alternates (same footprint): TDK PS1240P02BT (DigiKey 445-2525-1-ND, often backordered) or Same Sky CPT-1206-3TH-T (2223-CPT-1206-3TH-T-ND). Any ~12 mm two-pin piezo transducer (externally driven — not an "indicator") with ~5 mm pin spacing fits: the piezo pads are plated slots, so pin spacing anywhere from about 4 to 6 mm drops in (datasheet pitch is 5.0 ±0.5 mm, and the original round holes at exactly 5.0 mm were too tight for real parts).

Connections (all done by the PCB)

Paddle vs straight key: a TRS (stereo) plug = paddle on tip/ring. A TS (mono) straight-key plug grounds the ring permanently; the firmware detects this (at power-up, or after 8 s of continuous "dah") and turns the tip into a straight-key input — the status bar shows SKEY. Unplug it and paddle mode returns automatically.

Assembly

1. Solder the male pin headers to the ESP32 board pointing down (away from the screen).
2. Solder female sockets, the jack, and optionally the piezo to the shield top. The "USB" silk label marks the USB-C end. The jack only fits one way; the sockets are symmetric. The piezo transducer is unpolarized — if it has a "+" mark or longer lead, put it in the square pad (GPIO5) by convention.
3. Snap the ESP32 board in, screen up, USB-C over the "USB" label.

Regenerating

generate_shield.py builds the .kicad_pcb from scratch (see its header for the KiCad python invocation), then:

kicad-cli pcb drc --refill-zones --save-board --severity-error --exit-code-violations -o drc.rpt morsekey-shield.kicad_pcb
kicad-cli pcb export gerbers --check-zones -l "F.Cu,B.Cu,F.Paste,B.Paste,F.Silkscreen,B.Silkscreen,F.Mask,B.Mask,Edge.Cuts" -o gerbers/ morsekey-shield.kicad_pcb
kicad-cli pcb export drill --format excellon --excellon-separate-th -o gerbers/ morsekey-shield.kicad_pcb