u/GrapefruitForward357

Hi! I've been working on a small open-source project called TopreRT.

It started with a simple question: could Rapid Trigger be implemented on existing Topre keyboards using their original capacitive sensing hardware and stock PCB, without replacing the controller?

After reverse-engineering the firmware and sensor behavior, I eventually got it working on both an HHKB Professional Hybrid and a REALFORCE R3S.

Rapid Trigger processing happens directly on the keyboard itself. The toolkit takes a user-provided copy of the supported stock firmware, validates it, and generates a patched image with adjustable release and re-press distances. Stock or pre-patched firmware is not distributed with the project.

The current hardware-verified devices are:

HHKB Professional Hybrid / Hybrid Type-S (PD-KB800W), firmware A0.48
REALFORCE R3SB, firmware A0.12

R3SA/R3SC/R3SD A0.12 images are also supported at the binary-validation level, but I have not tested those models on physical hardware yet.

I've been using the modified HHKB as my normal keyboard for several days now, including normal typing, and it has been stable on my unit. The R3SB has also been tested on my own hardware.

The toolkit includes firmware validation, adjustable RT profiles, live telemetry/observer tools, and recovery guidance. The HHKB backend also has a built-in firmware writer and can restore the exact stock A0.48 image.

One important caveat: all physical hardware validation so far has been done on my own keyboards. I haven't received an independent installation report from another user yet. That's one of the main reasons I'm sharing this here — I'd really like to see how it behaves on other units of the supported models.

This is still an unofficial firmware modification, so flashing always carries some risk. I've tried to make the tooling fail closed wherever practical and to document recovery paths, but I don't want to present experimental firmware as risk-free.

TopreRT is free and open source:

GitHub: https://github.com/rocketman2654/TopreRT

I'd also be happy to answer technical questions about the implementation or anything I found while reverse-engineering these keyboards.

https://preview.redd.it/is8i9h74eljh1.png?width=1012&format=png&auto=webp&s=c51a3639800ad9ca5388f044bfbaca579b45e6cf

Hi! This is my first post here.

Over the past few days, I've been experimenting with the firmware used by the HHKB Professional Hybrid and REALFORCE R3 series.

The original question was pretty simple:

Could Rapid Trigger be implemented on a Topre keyboard that was never designed to support it?

It turns out that, at least on the hardware I've tested, the answer is yes.

I ended up building TopreRT, an open-source toolkit that implements Rapid Trigger while trying to preserve the original Topre sensor/state-machine behavior as much as possible.

For the HHKB Professional Hybrid / Hybrid Type-S (PD-KB800W, firmware A0.48), the current version supports:

All-key Rapid Trigger
Adjustable release and re-press distances
Stable and performance-oriented presets
Custom RT settings
Live key/sensor observation
Firmware validation before patching
Built-in firmware writer and stock restore

I've personally tested the RT core on my HHKB Professional Hybrid, and it is working.

The toolkit also supports the REALFORCE R3 family, although hardware validation varies by model.

Important: this is unofficial firmware modification software. There is always a risk of a failed update or recovery being required. The project does not distribute stock firmware or pre-patched firmware; you need to provide your own supported stock firmware image.

Source code, documentation, supported firmware versions, and recovery information are available on GitHub:

TopreRT v0.2.0:
https://github.com/rocketman2654/TopreRT

This started as a small experiment to see whether Rapid Trigger was even possible on these keyboards, and eventually turned into a toolkit supporting multiple Topre models.

I'd be interested to hear what other HHKB users think — especially if anyone wants to experiment with it or dig into the implementation.

I got Rapid Trigger working on stock Topre hardware without replacing the PCB

I got Rapid Trigger working on the HHKB Professional Hybrid — TopreRT v0.2.0