The MAXQ3100 microcontroller includes an on-chip temperature sensor, rewriteable EEPROM memory, and an LCD controller capable of direct driving up to 160 display segments. This article describes how to use the MAXQ3100 evaluation kit board along with the Rowley CrossWorks development system to create a temperature logging application in ANSI C. CrossWorks includes the capability to interface between C routines and native MAXQ’ assembly code, which allows the application to take advantage of built-in functions included in the MAXQ3100 utility ROM.