This project emulates the Timex Datalink Notebook Adapter for early Timex Datalink watches in Arduino! It is 100% compatible with the original Notebook Adapter, and works with vintage and modern computer hardware.

This Notebook Adapter emulator is tested to be compatible with:

• Timex Data Link® Software 2.1d
• Timex Ironman Triathlon® Data Link® 2.01
• Timex BeepwearPRO 1.03
• DSI Electronics e-BRAIN v1.1.6
• timex_datalink_client Ruby library

This project is not dependent on any specific Arduino board, although it has been tested to work with these devices:

• Teensy LC
• Raspberry Pi Pico

These boards have USB serial interfaces and onboard LEDs, so they can be used as-is without any external components:

The early Datalink watches receives data over light, and the original intent was to take advantage of a flashing electron beam on a CRT. Timex also offered a Notebook Adapter accessory intended for mobile users at the time, which replicates the data sent from a CRT using a single LED:

The Notebook Adapter is a serial device with a proprietary protocol that was reverse-engineered for this project. With the Arduino device present, the original Timex Datalink software can be configured to use the Notebook Adapter and send data to your watch:

The small onboard LED allows a Timex Datalink 150 watch to sync from a few inches away. With an external LED, it is possible to sync your watch from several feet away.

An LED can be added tidily to the Teensy LC by soldering an LED cathode (short leg) to the ground pin near the PROG pin, then connecting the anode (long leg) to pin 13 with a resistor, as pictured below.

I discovered that the best performance is obtained by using white LEDs, but every color I tested worked without problems. The LED pictured above is a white 20mA/3-3.2V 14000mcd LED paired with a stiff ¼W 22Ω resistor.