Totem he

Tot-HE-m

Tot-HE-m is a hall-effect version of GEIGEIGEIST's TOTEM: the same 38-key split layout, scaled to MX spacing, with a linear hall sensor under every switch instead of a mechanical contact. The goal is an analog keyboard that is cheap and easy to build at home. Each half is one two-layer PCB with a handful of SMD parts, a Seeed XIAO RP2040 and a 3D printed case, so everything can be ordered from LCSC, JLCPCB and the usual keyboard shops, and soldered with an ordinary iron.

Features

• Hall-effect sensing on every key, read through three 74HC4051 multiplexers per half. Tested with MMD C1 switches; other MX-style magnetic switches (Gateron KS-20, Wooting Lekker and similar) should work as well.
• Auto calibration. Each key measures its rest position at power-up and learns where it bottoms out while you type; the learnt travel is kept across reboots.
• Adjustable actuation and release points, set as key depth in tenths of a millimetre.
• Rapid trigger, with separate press and release sensitivity.
• VIA support: remap keys and change all of the above live from the browser.
• Controller layer: turns W A S D into an analog gamepad stick, so a light press walks and a full press runs.

Cost

Rough prices for one keyboard, checked October 2026, in euros, before shipping and taxes. Several parts only come in larger quantities, so ordering for two or more keyboards brings the price per board down a lot.

Ordering

PCB (JLCPCB). Upload production/Tot-HE-m_gerbers.zip on jlcpcb.com. The file holds both halves side by side, so an order of 5 gives 5 left and 5 right boards. Settings: 2 layers, 1.6 mm, 1 oz copper, any colour; the defaults cover the rest. JLCPCB counts the two outlines as two designs and adds a small fee for the second, which shows up in the quote. Pick "Remove order number", or it gets printed on the silkscreen.

Parts (LCSC). On lcsc.com, open the BOM tool, upload production/lcsc_bom.csv and match the "LCSC Part Number" column. That puts every SMD part and both jacks in the cart in one go, with a few spares for the small parts:

Everything else: two Seeed XIAO RP2040s, 38 magnetic switches, 38 MX keycaps, a 4-pole TRRS cable, a USB-C cable, eight M2 x 10 screws and at least eight rubber bumpers taller than 2.5 mm.

The cable has to be TRRS (three insulating rings on the plug). A 3-pole TRS cable bridges two contacts in the jack and shorts the 3.3 V supply, and the keyboard stays dark.

Building

1. Solder the bottom side first: one hall sensor under every switch position, the three muxes and the capacitors. The sensors are wired pin 1 VCC, 2 OUT, 3 GND, the DRV5055's own SOT-23 order.
2. Solder the XIAO flat on its castellated pads, without headers, and the TRRS jack on top. Check every XIAO pad, GND and D8 to D10 in particular: a dry joint there makes all keys read wrong.
3. Flash the firmware (below) and check that every key types before closing the case.
4. Clip the switches into the printed plate, put the plate on the PCB, drop the shell over it and fasten each corner with an M2 x 10 screw from below, then stick the bumpers on.

Only plug or unplug the TRRS cable with USB disconnected.

Firmware and VIA

The firmware is QMK. Hold the XIAO's BOOT button while plugging a half in; it shows up as a drive called RPI-RP2. Copy firmware/uf2/tot_he_m_via_left.uf2 onto the left half and tot_he_m_via_right.uf2 onto the right. Each image stores its side on first boot. Afterwards, hold Esc and press T to get back into the bootloader.

To configure it in VIA:

1. Open usevia.app in a Chromium-based browser.
2. Under Settings, turn on Show Design tab.
3. In the Design tab, load firmware/via/tot-he-m.json. VIA forgets it when the browser closes, so load it again next time.
4. In Configure, click Authorize device and pick Tot-HE-m.

The keymap editor then works as on any VIA keyboard, and the Hall effect menu has the analog settings:

Settings are stored on the half that is plugged in, which sends them to the other half. On Linux, the browser needs access to the keyboard's hidraw device; a udev rule for vendor 746d, product 7e57 with TAG+="uaccess" does it.

The default keymap follows a Ferris Sweep layout: QWERTY with Ctrl and Alt on the outer bottom keys and, on the thumbs, Shift, Space and Esc on the left, Enter, Backspace and GUI on the right. Holding Backspace gives numbers and symbols, Enter navigation and F-keys, Esc system keys. Hold Esc and press G for the controller layer.

To build the firmware yourself, copy firmware/qmk/tot_he_m into keyboards/ of a QMK checkout and run, for each half:

qmk compile -kb tot_he_m -km via -e EXTRAFLAGS=-DINIT_EE_HANDS_LEFT -e TARGET=tot_he_m_via_left
qmk compile -kb tot_he_m -km via -e EXTRAFLAGS=-DINIT_EE_HANDS_RIGHT -e TARGET=tot_he_m_via_right

Case

Each half is a shell and a switch plate, both printed without supports: the shell deck-down, the plate top-down. The stack is the 1.6 mm PCB, the plate 5 mm above it and the deck 6 mm above the plate, 12.6 mm in total. Each M2 x 10 screw goes up from under the PCB, through the plate's standoff, and cuts its own thread in a pilot hole in the deck. The screw heads sit under the PCB, so the bumpers need to be taller than 2.5 mm. For a case that gets opened often, set insert = true in case/totem_he_case.scad to use M2 heat-set inserts instead.

The foam mold casts an optional silicone foam layer between the PCB and the plate, which dampens the sound; the instructions are at the top of case/foam_mold.scad.

The STLs are in case/stl, made from the OpenSCAD sources (OpenSCAD 2025 or newer):

openscad --enable=roof -D 'part="shell"' -D 'side="left"' -o case/stl/totemhe_shell_left.stl case/totem_he_case.scad

Repository

License

The PCB, case and everything else outside firmware/ are licensed under CC BY-NC-SA 4.0, like TOTEM, which they are derived from: share and adapt them freely for non-commercial use, with attribution, under the same license. The firmware in firmware/ is GPL-2.0-or-later, like QMK.

Credits

Layout and outline from TOTEM by GEIGEIGEIST. The sensor scan is modelled on Boardloaf-HE, the per-key calibration on Hector. Some footprints are adapted from ceoloide's Ergogen footprints (see pcb/footprints/LICENSE-ceoloide).