Plugin: PixArt Touchpad

Introduction

The PixArt Touchpad plugin updates PixArt touchpad firmware that enumerates as HID devices, either USB-HID or I²C-HID exposed via hidraw.

The device can enter a lightweight bootloader (“engineer mode”) and is then flashed over the same HID interface.

This plugin sets the fwupd device protocol to com.pixart.tp and reports version numbers in hex format.

Firmware Format

The firmware is parsed by FuPixartTpFirmware and validated using:

  • Magic FWHD (header v1.0)
  • Header CRC32 (over the header minus CRC field)
  • Payload CRC32 (over the bytes after the header)

Each updateable internal section defines a flash start address and a file offset/length. The plugin programs flash in 4 KiB sectors with 256-byte pages via a small SRAM window.

GUID Generation

These devices use the standard HID DeviceInstanceId values, e.g.

  • HIDRAW\VEN_093A&DEV_0343

Note: If the same silicon enumerates as a USB interface on some systems, an additional USB GUID like USB\VID_093A&PID_0343 may also be provided in the firmware metadata. GUIDs derived from hardware IDs are stable across machines.

Update Behavior

High-level flow:

  1. Detach (enter bootloader) Writes device registers to switch to engineer mode:
  2. bank 0x01, reg 0x2c = 0xaa

  3. bank 0x01, reg 0x2d = 0xcc

  4. Erase/Program

  5. Erase flash by sector (4 KiB)
  6. Program by page (256 B) using an SRAM selected by SramSelect

  7. Busy/write-enable checks are performed between operations

  8. Attach (exit bootloader)

  9. bank 0x01, reg 0x2c = 0xaa
  10. bank 0x01, reg 0x2d = 0xbb

OS reboot is required.

Quirk Use

This plugin supports the following plugin-specific quirks:

PixartTpHidVersionBank

Defines which bank to read the device firmware version from. Default: 0x00.

PixartTpHidVersionAddr

Defines which address to read the device firmware version from; the plugin reads addr+0 (lo) and addr+1 (hi). Default: 0xb2.

PixartTpSramSelect

Selects the SRAM type used for 256-byte page programming. Default: 0x0f.

PixartTpHasHaptic

Whether this TP has a TF/haptic child IC.

Default: false.

Vendor ID Security

The vendor ID is set from the HID vendor, in this instance set to HIDRAW:0x093A

Version Considerations

This plugin has been available since fwupd version 2.0.19.