Reading Small changes in voltages

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi everyone,
I am having a problem interfacing an arduino with a motorcycle gear position sensor. The sensor acts like a potentiometer outputting different voltages at different gears.

The problem is that the differences in values between different gears are TINY. the difference at 5v between the first couple of gears is only .001(5V vs. 4.999) and then the other gears are only like .005 difference. So the problem is that the analogRead() simply reads all of the voltages as 1023.

Any ideas on how to deal with a problem like this?

Thank you,
M3Shark

2

not borken, but i think it is actually supposed to be giving out resistance values not voltage. In different gears the resistance changes as follows:

Gear 1- 563 ohms
2-825 ohms
3- 1500 ohms
4 - 2700 ohms
5 - 6700 ohms
6 - 15000 ohms

but i don't know how to go about reading a resistance value with a analogRead(), call. I know i cant read resistance directly, but how do i go about reading it.

Thank you for your help.

3

but i don't know how to go about reading a resistance value

Use a pull up resistor.

Wire one of the wires from your sensor to ground and the other to the analogue input. Then put a resistor from the analogue input to +5V. make the resistor something between 10K and 20K. You should then have good reading to play with.