HandShake is an assistive technology device that uses the Lilygo T-Watch S3 or the Lilygo T-Embed. This website contains the tools to configure your device and build the firmware for it. For more information on the HandShake project, see this page or about this site.
Getting Started
Select the relevant Configuration tab for your device to set the functionality you want, then create and download the firmware. You save this to your own laptop, PC or phone. You own it. No licence, no subscription. It’s yours.
Use the Device Flasher page to flash your firmware to the T-Watch or the T-Embed - the same page works with both devices.
Don’t worry if you flash the T-Watch firmware to the T-Embed or vice-versa, just reflash with the correct firmware. You won’t break it!
Privacy
This site collects no personal information.
The information that is logged is:
- When firmware is created and how long it took to create (configuration information is not stored after the session expires).
- When errors occur.
This is done so that I can keep track of whether the site is working fast enough and whether I need to fix anything.
If information you entered during the last session appears in any controls, it is because your computer’s cache stored it, not because I’ve stored it. Once your session expires, your setup data is deleted from this server. The settings that appear when you first use the system are the default values that I use.
Limitations
The system is configured so that there can be up to 8 sessions active. However, it takes an hour for a session to expire. If you can’t get onto the system, let me know and I’ll look at reconfiguring things to allow more users.
About this service
HandShake is a free, open-source configuration and firmware service for the Lilygo T-Watch S3 and T-Embed. It lets you generate and flash device firmware that turns these devices into components of an AAC (Augmentative and Alternative Communication) switch interface.
We do not sell, modify, or supply hardware. Devices are purchased directly from Lilygo and arrive as unmodified, manufacturer-certified products (CE/FCC). This site provides configuration and firmware only.
No warranty
This software is provided “as is”, without warranty of any kind, express or implied, including but not limited to warranties of merchantability, fitness for a particular purpose, and non-infringement. In no event shall the authors or contributors be liable for any claim, damages, or other liability arising from, out of, or in connection with the software or its use.
Important safety note
HandShake-configured devices may be used to support access to communication for people who rely on AAC. Because of this, we strongly recommend:
- Initial setup and switch-function testing is carried out or supervised by a relevant professional (occupational therapist, speech and language therapist, technologist or experienced carer).
- Switch response is verified — confirming reliable activation and no false triggers — before any unsupervised or high-stakes use.
- The firmware version identifier is noted for each deployed device, so any issue can be traced to a specific build.
- Faults or unexpected behaviour are reported promptly using the link below, and the affected device is taken out of use until resolved.
This tool is provided in good faith to support AAC access, but it is not a certified medical device, and responsibility for confirming a device’s suitability for an individual’s needs rests with the person or professional deploying it.
Reporting issues
Found a bug, or had a device behave unexpectedly? Please contact matt@mattoppenheim.com. Include a description of what happened — this helps us fix it and warn other users if needed.
License
HandShake firmware is licensed under AGPLv3. This configuration website’s source will be made available once it’s fully functional and tested at https://gitlab.com/mattoppenheim/handshake/handshake_website
Build: 2026-07-30 11:00:09 UTC