Resistive sensor interfacing with controller

[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

 

[nbucska]

If the quantity is analog/multivalue quantity:

You need an interface circuit ( Voltage ref & op.amp )
and ADC. You may need additional pins to interface
to controller but these may be shared among more functions

If it is on/off ( e.g. one value = on, other = off)

Comparator with R-network.

More ? <nbucska@pcperipherals.com>

 

[ank]

to nbucska

Hi!
Is there are some sample schematics in the internet?

ank

 

[electricuwe]

You can use the sesor resistor together with a fixed resitor in a voltage divider connection and sense the voltage at the midpoint with an analog input of the controller. You will loose part of the available input range and resolution and you will need some additional calculations, but this will be a very costeffective approach.

 

[nbucska]

Need more data and FAX #. <nbucska@pcperipherals.com>

 

[melone]

What is the final application?

 

[cbarn24050]

Hi, what micro are u using, what type of port do u have free