Hall Effect Keyboard Design
Thought for 1 min 3 sec
I started the layout phase and inspected the current PCB state. The board is still the default 160 × 100 mm, 4-layer layout, and the components are spread far outside the board from schematic-origin placement, so placement needs to be redone after sizing.
Open items:
- I’m blocked because the account has no available ACUs.
- Board outline still needs to be resized to a real TKL footprint.
- Component placement has not been run yet.
Suggested next steps:
- Add ACUs, then resize the board to a standard TKL outline.
- Place the USB-C connector at the rear edge, encoder at the top-right, mux/MCU cluster centrally, and Hall sensors on the switch grid.
- Run post-placement DRC before routing.
continue
Thought for 4 sec
I’ll continue layout setup: apply a standard TKL board size/outline, then place the major blocks according to the keyboard geometry and run a quick layout check if resources are available.
Worked for 8 mins 36 sec
I continued layout setup: resized the PCB to a 365 × 140 mm 4-layer TKL board and placed all 213 components, including the 87 Hall sensors in a TKL-style grid, USB-C/ESD/power at the rear edge, MCU/muxes centrally, and encoder at the top-right.
Open items:
- I’m blocked from running the post-placement DRC because the account has no available ACUs.
- Placement reported no overlap/out-of-bounds issues, but final board checks still need to be run.
- Magnetic Jade Max mechanical sensor alignment still needs physical validation.
Suggested next steps:
- Add ACUs, then rerun post-placement DRC.
- Verify Hall sensor position vs Magnetic Jade Max switch magnet travel.
- Route the board after placement checks pass.
Route and verify
Route critical nets
Verify Hall alignment
Prepare DRC checklist
Review placement risks
Refine this doc
Ask about this doc
Project Specification: TKL Hall Effect Keyboard
Summary
Design a standard TKL-size wired USB-C Hall-effect computer keyboard PCB using Gateron Magnetic Jade Max HE / MX-style magnetic switches, with continuous analog key-position reporting for supported apps/games and an app-configurable firmware architecture. Low input latency is the top design priority.
User-declared requirements
- Layout: standard TKL size.
- Switch sensing: Hall-effect / magnetic switch architecture.
- Target switch family: Gateron Magnetic Jade Max HE, or a mechanically/electrically compatible MX-style Hall-effect switch.
- Continuous analog behavior: the keyboard should expose calibrated key-position data for supported apps/games, not only emit a digital event at a fixed actuation point.
- USB behavior: enumerate as a standard USB HID keyboard plus a second optional analog HID interface for analog-aware apps/games.
- Compatibility: normal keyboard operation must work without custom drivers, background software, proprietary APIs, or vendor software installed.
- Rapid Trigger: implement entirely in firmware while still sending ordinary keyboard press/release reports to the host.
- Latency priority: minimize scan-to-USB/report latency above all nonessential features.
- Hot-swap support for the selected MX-style Hall-effect switch ecosystem.
- Rotary encoder.
- USB-C wired host connection.
- ESD protection on external USB interface.
- App-configurable keyboard behavior planned.
- No RGB and no keyboard lighting circuitry.
Proposed architecture
- MCU with native USB and enough I/O/ADC expansion for analog Hall scanning; default candidate: RP2040-class MCU plus analog multiplexers or ADC expansion as needed.
- USB-C receptacle with USB 2.0 device wiring, CC pull-downs, VBUS protection, and D+/D- ESD array.
- 3.3 V logic rail from USB 5 V.
- Hall-effect sensing per key with scan/mux architecture suitable for continuous position readout, rapid-trigger behavior, and analog actuation firmware.
- Firmware normalizes each key from raw ADC counts into calibrated travel/position values; standard HID keypresses are derived from configurable thresholds for OS compatibility.
- Composite USB HID device model:
- Interface 0: standard Keyboard HID for normal apps and OS-level keyboard behavior.
- Interface 1: optional Analog HID for supported apps/games to read per-key position, visible as 0–100% or equivalent normalized values.
- Avoid gamepad/Xbox-controller emulation as the default analog output path because it can confuse game UI prompts, desktop behavior, and anti-cheat systems.
- Low-latency firmware path: prioritize high scan rate, short ADC acquisition windows compatible with sensor settling, minimal filtering delay, interrupt/DMA-assisted sampling where practical, and frequent USB reports.
- Hot-swap mechanical/electrical interface documented as switch-family dependent; exact Gateron Magnetic Jade Max HE-compatible switch/socket/sensor footprint must be finalized before per-key circuits are completed.
- Rotary encoder connected to GPIO with pull-ups/debounce support.
- Firmware/app interface: standard USB Keyboard HID plus dedicated Analog HID for live position data, with optional configuration/control reports for calibration and settings.
- No LED driver, per-key RGB, underglow, backlight, or indicator LED network is included unless explicitly added later by the user.
Switch notes
- Gateron Magnetic Jade Max HE is a linear Hall-effect magnetic switch for Hall-effect keyboards, not ordinary mechanical contact PCBs.
- Published specs list approximately 3.5 ± 0.1 mm total travel and freely configurable actuation/pre-travel via compatible firmware/software.
- The switch choice reinforces the need for per-key Hall sensing and calibration rather than contact-matrix scanning.
Open decisions
- Exact Hall sensor and PCB footprint/placement geometry compatible with Gateron Magnetic Jade Max HE.
- Exact hot-swap/socket or plate/PCB retention strategy for the selected switch ecosystem.
- Exact TKL physical outline and mounting hole/case compatibility.
- Final Analog HID report descriptor and report packing for low-latency app/game support.
Validation targets
- USB enumerates reliably as a composite HID device with standard Keyboard HID plus optional Analog HID.
- Keyboard HID works in normal applications without vendor software or custom drivers.
- ESD parts located close to connector in layout.
- 3.3 V rail sized for MCU, Hall sensors, encoder, muxes, and flash; no lighting load budget required.
- Firmware can read every Hall channel and store calibration data.
- App/game interface can stream/report continuous normalized key-position data from 0–100% or equivalent fixed-point range.
- Rapid Trigger behavior is handled in firmware and produces ordinary key down/up reports.
- Scan-to-report latency is measured and optimized; avoid heavy filtering that increases latency.
- BOM and schematic contain no RGB/lighting parts.
Summary
User-declared requirements
Proposed architecture
Switch notes
Open decisions
Validation targets
