ErgonomicGamepad

ErgonomicGamepad

Custom ergonomic gaming keypad PCB project (KiCad) with a 4x6 key matrix, hot-swap sockets, and USB-C.

Overview

This repo contains the schematic, PCB, and production support files for an ATmega32U4-based ergonomic keypad.

Hardware Summary

Core Project Files

• ErgonomicGamepad.kicad_sch - Schematic
• ErgonomicGamepad.kicad_pcb - PCB layout
• ErgonomicGamepad.kicad_pro - KiCad project
• jlcpcb/production_files/jlc_sourcing_bom_template.csv - Main sourcing/BOM table
• jlcpcb/production_files/verify_stock_before_ordering.csv - Pre-order stock/sourcing risk checklist (MCU lead time, hand-sourced sockets/connectors/switches)
• jlcpcb/gerber/ - Manufacturing output folder

Pinout Baseline

Matrix

Programming Header (ISP)

USB-C Implementation (Resolved)

J1 is an HRO TYPE-C-31-M-12 receptacle - hybrid retention (SMT signal/power pins plus through-hole shell tabs) for stronger cable-insertion durability than an SMT-only part. This is a USB 2.0 device-only implementation (power + D+/D-); no SuperSpeed/Alt-Mode pins are used.

• Orientation: fully reversible. Both D+ pads (A6 and B6) are tied together at the connector, and both D- pads (A7 and B7) are tied together, so the plug works in either orientation.
• Signal path: connector D+/D- -> U2 (USBLC6-2SC6 ESD protection array) -> series resistors R1/R2 (20R) -> U1 D-/D+ pins, with TP3/TP4 tapping the MCU-side D-/D+ nets for debug access.
• CC (device-mode/UFP): CC1 and CC2 each pull down to GND through a 5.1k resistor (R4, R5) - the standard passive UFP presentation, no CC logic IC.
• Shield/GND: J1's shield pin (SH) ties directly to GND (no RC/ferrite isolation).
• Power path: VBUS feeds +5V through D1 (1N5819WS Schottky) gated by JP1 (power-path select jumper - see Jumper Shunts below); J7 (external 2-pin power connector) feeds +5V directly. The Schottky prevents VBUS from being back-fed if J7 external power is connected while a USB cable is also plugged in.

Debug / Test Points

• TP1-TP7: internal signal debug points (power-select node, GND reference, USB D+/D-, crystal XTAL1/XTAL2, USB regulator cap node) using the small TestPoint_Pad_D1.5mm footprint - sized for a fine meter probe or hook, not a full-size clip.
• TP8 (+5V) / TP9 (GND): dedicated power-rail clip points, intended to be placed at the board edge for easy alligator-clip access during bring-up and testing. These use the larger TestPoint_THTPad_D3.0mm_Drill1.5mm footprint (a real drilled through-hole pad, not just a flat SMD pad) so an actual clip has something to bite onto. Kept separate from TP2 (which stays with the internal signal-debug cluster near the MCU) since GND is a single net and a second access point elsewhere costs nothing electrically.

Footprint Baseline (Current)

• SW1-SW24: Switch_Keyboard_Hotswap_Kailh:SW_Hotswap_Kailh_MX_Plated_1.00u
• J1: Connector_USB:USB_C_Receptacle_HRO_TYPE-C-31-M-12
• R1-R7: Resistor_SMD:R_0603_1608Metric
• C1-C5: Capacitor_SMD:C_0603_1608Metric
• D25-D26: LED_SMD:LED_0603_1608Metric
• TP1-TP7: TestPoint:TestPoint_Pad_D1.5mm
• TP8/TP9: TestPoint:TestPoint_THTPad_D3.0mm_Drill1.5mm (edge-mounted power/ground clip points - see Debug / Test Points above)
• J2/J3/J4/J6: Connector_JST:JST_XH_B5B-XH-A_1x05_P2.50mm_Vertical (DNP - see Satellite Board Cables below)
• J7: PinHeader_1x02_P2.54mm_Vertical
• J5: PinHeader_2x03_P2.54mm_Vertical
• JP1/JP2: Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical
• Y1: Crystal:Crystal_SMD_3215-2Pin_3.2x1.5mm
• SWR1: Button_Switch_SMD:SW_SPST_B3U-3000P

Jumper Shunts Needed (Not Part of PCBA)

JP1 (power-path select) and JP2 (forces hardware bootloader via U1 pin 33 / HWB when bridged) are populated as bare 2-pin headers during JLCPCB assembly, but the assembly process does not install a shunt on them - a jumper shunt is a friction-fit plastic/metal cap, not a soldered part, so it has to be installed by hand after the boards arrive.

Buy separately (not on the PCBA BOM):

• 2.54mm 2-pin jumper shunt cap - e.g. BOOMELE, LCSC C5305 (~$0.01/unit, 50-piece minimum order on LCSC). Any standard 2.54mm/0.1" shunt works; this is a common commodity part also sold on Amazon/DigiKey/etc.
• Need at least 2 (one per jumper), but buy a small handful (the LCSC MOQ is 50 anyway) since they're easy to lose.

Switches & Keycaps Needed (Not Part of PCBA)

SW01-SW24 are Kailh MX hotswap sockets, soldered directly to the board (see Footprint Baseline above), but the actual keyswitches and keycaps are separate hand-sourced items that get plugged in after assembly - the whole point of a hotswap board is that these aren't soldered.

• Hotswap sockets (on-board, hand-soldered): Kailh CPG151101S11-16, LCSC C5156480 - https://www.lcsc.com/datasheet/C5156480.pdf. Currently shows near-zero LCSC stock (consignment-style listing), so plan to hand-source and hand-solder these rather than rely on JLCPCB auto-placement - see Progress notes below. Need 24 plus a few spares. Each socket takes 2 solder joints (through-hole); the extra alignment pins in the footprint hold it steady while soldering. For practical hobbyist purchasing, the real path is AliExpress - there are multiple listings selling genuine Kailh hotswap sockets in small hobbyist-friendly quantities (30/90/110-packs), which is how most individual keyboard builders actually buy these - or a specialty keyboard-parts retailer like splitkb.com, which stocks Kailh hotswap sockets specifically for this use case.
• Keyswitches (plug into the sockets, not soldered): Cherry MX Brown (tactile), official part MX1A-G1NW. Also frequently out of stock on LCSC - source from a specialty mechanical-keyboard parts retailer instead (e.g. KBDfans, NovelKeys, Mechanicalkeyboards.com, or similar). Since the socket is switch-agnostic (any standard MX-footprint switch fits), a well-regarded MX-compatible clone switch would also work if genuine Cherry isn't available. Need 24 plus a few spares.
• Keycaps: MX-compatible (cross-stem) keycaps, not yet specced - profile (OEM/Cherry/DSA/etc.), material, and colorway are a personal choice. Note this layout is a non-standard ergonomic 4x6 matrix, not a regular keyboard row layout, so a generic pre-made keycap set is unlikely to have correctly-sculpted keycaps for every position - uniform-profile (same shape regardless of position) or blank keycaps are the simplest option unless a custom set is planned.

Satellite Board Cables Needed (Not Part of PCBA)

J2/J3/J4/J6 connect the two satellite switch boards to the main board (ROW1-4

• COL1 per connector - no power needed, see Pinout Baseline). They're marked DNP on the JLCPCB assembly BOM since through-hole headers get hand-soldered after the boards arrive, same reasoning as the hotswap sockets above.

• Male headers (on-board, hand-soldered): JST-XH 5-pin, B5B-XH-A (matches the footprint above). Genuine JST stock from Digi-Key or Mouser (search B5B-XH-A directly), or cheaper from LCSC/JLCPCB (search "XH 5P" or the part number B5B-XH-A(LF)(SN)) - the latter is also orderable through JLCPCB assembly if DNP is ever lifted. Generic multi-packs from Amazon/AliExpress work fine too for prototyping. Need 4 (one per connector) plus spares.
• Female-to-female cables: JST-XH 5-pin, both ends female, connecting each main-board header to its matching satellite-board header. Target length ~3-4in. Best sourced from AliExpress (search "JST XH 2.54 5 pin cable" - widely available in 10/15/20/30cm, some sellers offer custom lengths) or Amazon (search "JST XH 5 pin cable" - mostly RC/battery sellers, lengths cluster around 15-30cm with some 10cm/4in options). If the exact length/pinout combo isn't available premade, a JST-XH crimp tool ($15-20) plus loose housings/terminals (pennies each, same vendors) makes it easy to build the 2 needed cables to spec. Individual wires are flexible (stranded, not ribbon) so routing/twisting around the enclosure isn't a concern.

Progress (Brief)

Done:

• Schematic is component-complete.
• Footprints assigned for all currently tracked parts.
• Schematic and PCB baseline are synced.
• ISP signal mapping corrected and documented.
• JLC sourcing workflow files are in place.
• USB-C orientation, CC, ESD, shield, and power-path decisions locked and documented.

Not done yet:

• Component placement refinement.
• PCB routing completion.
• Panelization/mechanical finalization.
• Final DRC-clean release candidate.
• Gerber/BOM/CPL release package for fabrication.
• Firmware development.

Process Checklist

For the full detailed build, verification, and manufacturing checklist, use PROCESS.md.

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Last Updated: July 2026 Project Status: Pre-Layout Baseline