Atmel STK502 - Manual (Page 17)

Using the STK502 Top Module
STK502 User Guide 2-11
2528A–AVR–11/02
2.7 Sensor Figure 2-16. NTC-thermistor
STK502 includes a two screw-terminal block where a sensor can be connected. The
STK502 kit is shipped with a NTC-thermistor attached to this screw-terminal. A NTC-
thermistor is characterised by the fact that when the temperature goes down the resis-
tance goes up. Using a voltage divider and reading the voltage over the thermistor
through the ADC-channels on ATmega169, the temperature can be calculated. Applica-
tion note “AVR064: STK502 – A Temperature Monitoring System with LCD Output”
describes the details of the application.
2.7.1 Sensor Switches Two switches on the STK502 are used to connect the sensor to the ADC-channels on
the ATmega169 as shown in Figure 2-17.
Figure 2-17. Temperature sensor switches