Setting up the Lilygo T-Watch S3

Fri, 07 Aug 2026 00:00:00 +0000

This page shows how to set up the Lilygo T-Watch S3 to work as part of the handshake project.

Summary

Turn on the watch using a long press on the button.

Shake the watch gently and check that this is detected as a switch by the receiver unit.

Adjust the level of shake that will trigger a switch action using the jog dial on the receiver, followed by a long press on the button in the middle of the jog dial. This sends the new shake detection threshold to the watch.

handshake components

The handshake system comprises two parts, a smart watch (Lilygo T-Watch S3) and a receiver unit that sends a keystroke to a communication device (Lilygo T-Embed) through a USB cable. The two devices are shown in the photo below.

Lilygo T-Watch S3 and Lilygo T-Embed

TO ADD TO THE HOW-TO

When the watch has booted up, which takes a few seconds, you will see the display below:

Watch default display

The top slider displays shows the current amount of shake that is detected by the watch. This updates real time.

The bottom slider displays the amount of shake necessary to operate your communication software. The value for this threshold is displayed on the watch screen as ‘shake trigger: xxx’ where xxx is a number that varies from 525 to 1000 (these limits may change). The lower the number, the softer the motion required to trigger a shake detection.

As the watch is moved around, the top slider will display real-time how much shake force is being detected by the shake sensor inside the watch. Once the top slider is to the right of the bottom slider, the shake detection is triggered.

When an intended shake is detected this display is shown on the watch:

Shake detected display

When an unintended violent shake is detected this display is shown on the watch:

Unintended shake detected display

To charge the watch, attach a USB cable to the micro USB socket in the side of the watch and connect to a USB socket or charger. For whatever reason, once the watch battery is at 0% it stays at 0% for an age while charging then starts ramping up to 100% fairly quickly. I don’t know how to improve this yet.

Charging the watch

Setting up the receiver unit

The T-Embed receiver unit is powered from the USB-C socket on its side.

The receiver has a jog dial around the button. This dial is used to adjust the trigger threshold. Use the dial to set a new trigger threshold then send this new value to the watch by giving a long press (about 2s) to the button in the middle of the dial. Turning the jog wheel clockwise will increase the amount of shake needed to send a trigger to your communication device, turning the jog wheel anti-clockwise decreases the amount of shake needed to send a trigger to your communication device. The updated trigger will not take effect in the watch until you give a long press on the button though. Check the watch to see that the new shake value is shown on the watch display.

The button on the receiver has three uses:

A long press: The receiver sends the trigger threshold shown on the receiver display to the watch.

A short press: The unit receives the greatest shake value for the last 5s from the watch so you can tune in the right trigger level.

A double tap: Sends a trigger signal from the receiver through the 3.5mm socket so you can check that your communication device responds.

T-Watch S3 on HandShakeTec

Setting up the Lilygo T-Watch S3

Summary

handshake components

Setting up the receiver unit