@paulcrawfordgm turned the W1209 Data Logging Thermostat into a cooling controller with a serial interface:

The project started here on HaD, continued with an STM8 eForth issue, and was completed in TG9541/W1209 issue #22.

Paul achieved the following:

• coping with a non-standard W1209 board variant (Nuvoton chip, 5K NTC pull-up)
• set-up of Travis-CI for Paul's fork of the TG9541/W1209 repo
• changed control.fs from heating to cooling
• menu adapted and simplified, logger.fs removed
• serial interface for temperature data with counter and CRC-16

The process of problem resolution and the Forth learning process worth reading!