T430 Revision A wiring
Revision A replaced the nRF52840 DK with a HolyIOT 18010 module. It proved the keyboard, TrackPoint movement, USB, Bluetooth, LEDs, battery power, and update path on a custom board. It includes a backlight control circuit, but the backlight caused resets during testing and remains disabled in release firmware.
Use these files for exact construction details:
Revision A is historical. Do not use it as the starting point for Revision B.
Interfaces
The board connects:
- the T430 16-by-8 keyboard matrix;
- separate Fn and power-button inputs;
- TrackPoint DATA, CLOCK, RESET, and three buttons;
- the power, speaker-mute, and microphone-mute LEDs;
- three Bluetooth profile LEDs;
- keyboard backlight PWM and power control;
- USB 2.0 device data; and
- SWD through a Tag-Connect footprint.
The nRF52840 uses 3.0 V logic. The keyboard matrix uses internal pull-ups. TrackPoint DATA and CLOCK cross between 3.0 V and 5 V through BSS138 level shifters. Never connect a 5 V signal directly to the module.
Power
Revision A uses these rails:
| Rail | Purpose |
|---|---|
USB_VBUS_RAW | Protected USB input and presence detection |
VSYS | Charger power-path output |
VSYS_SW | Main switched system supply |
VCC | Regulated 3.0 V logic and module supply |
+5V | Boost output for TrackPoint and backlight |
The latching power button controls the main P-channel MOSFET. The T430 power button remains a firmware input. The reset button only drives nRESET.
The charger remains connected when the main system power is off. Use only a protected single-cell 4.2 V Li-ion or LiPo battery with the marked polarity.
Programming and updates
The Tag-Connect footprint provides SWDIO, SWCLK, nRESET, VCC sense, and ground. The target powers itself; an external debugger must not drive the 3.0 V rail.
SWD installs or recovers the UF2 bootloader. Normal development uses USB and UF2. See Revision A programming.
Known Revision A issues
- TrackPoint reset polarity requires a firmware workaround.
- The original charger and power path are replaced in Revision B.
- Fine-pitch assembly and connector inspection need better test coverage.
- TrackPoint and backlight current require separate measurement points.
- Repeated development must not depend on holding a Tag-Connect probe.
The Revision A bring-up record contains the measurements and resulting Revision B requirements.