I need help with interfacing resistive sensor

[ank]

Hi!

I need help with interfacing resistive sensor to microcontroller. Sensor resistance changing between 100kohm to 2Megaohm. I must use only one pin on controller. That mean I need some kind of relay output circuit. But which kind of circuit give me good results.

Ank

 

[steve3108]

Ank:

What you need is a temperature transmitter. The device will take the sensor output and give you a control signal (i.e. 4-20ma or 0-10v) that the controller will recognize. Check out

http://www.kele.com.

They have transmitters for a variety of sensors and applications. I hope this helps.

Steve3108

 

[buzzp]

Do you have to display this temp? Or is some action required at a given temperature(and therefore given resistance)? If you just need to switch at a given temp then use a voltage divider biased with 5V and use the digital input on the microcontroller. This is not the most accurate method but it suits a lot of applications. If you need to know the exact temperature then the only way to do it is to float the signal on some reference voltage (depends on whether TC is positive or negative) and use a microcontroller with an AD converter or buy an AD IC.