Measuring resistance using analog breakout

[Mike Betts]

Originally Posted by ajd

Our team is interested in using sensors that change the resistance of a wire based on an input. We read the datasheet for the Analog Breakout and it included instructions for reading a potentiometer, which has three wires, so that there is a constant resistance between the +5V and GND and a variable resistance between both (+5V and SIG) and (SIG and GND). But what if a sensor only has two wires, and simply adjusts the resistance between them? Do we wire +5V to SIG through the resistor, or SIG to GND, or something more complicated?

Thanks.

There are several passive circuits such as resistance bridges and the aforementioned voltage dividers. There are also active circuits that can be used.

For resistance dividers, you have to be a little careful choosing resistance values based on the power rating of the sensor, input resistance of the analog module, et cetera.

Before you start implementing anything, why don't you post the part number you looking to use. This will allow the EEs out there to make specific recommendations.

I'll be tied up at the WPI regional for the next few days but I'm certain that someone will make a recommendation for you.

Mike

[ajd]

Thank you all very much for the information and help! I think now that we understand the basic concept of what needs to be done, I can work with a mentor on my time to figure out the math. (If anyone's curious, we're trying to implement a simple light sensor from a photocell for purely academic/learning purposes.)

Thanks!