December 2010

Doc ID 17836 Rev 1

1/24

AN3260

Application note

Building a thermometer

using the STM8S-DISCOVERY

Application overview

This application demonstrates how to build a simple thermometer based on the STM8S-

DISCOVERY and the LM235 precision temperature sensor. The STM8S105C6T6

microcontroller reads the temperature values and transmits them through the UART

interface. The temperature values are then displayed on a terminal window (possibly based

on Windows HyperTerminal) of a PC connected to the UART through an RS232 cable.

Once the STM8S-DISCOVERY is powered up through an USB cable connected to the host

PC, an informative message is displayed on the terminal window and the user is prompted

to enter minimum and maximum temperature thresholds.

The current temperature is displayed on the terminal window every minute together with a

warning message when the temperature is out of range.

The minimum and maximum values of the temperature over one-hour period are recorded in

the MCU data EEPROM once per hour. They can be displayed any time by pressing a

pushbutton.

Even if it is built on an STM8S105C6T6, the STM8S-DISCOVERY can be used to evaluate

the main features of all STM8S microcontrollers.

Reference documents

I

STM8S-DISCOVERY evaluation board user manual (UM0817).

I

Developing and debugging your STM8S-DISCOVERY application code user manual

(UM0834).

I

LM235 precision temperature sensor datasheet

I

ST232C 5 V powered multi-channel RS-232 driver and receiver datasheet

www.st.com