Hooking up an analog foot pedal

Hi I'm trying to figure out how to hook up properly an analog foot pedal from Adafruit:


I have it going ground -> 10KOhm resistor -> analog input but changing the foot pedal does nothing. I also tried going directly ground to analog but it was no better. What am I missing here? When I check it with a meter, I'm showing 20KOhms that decrease as the pedal is pushed. So I know the device is working.

Please help.

Wrong connections. It should be one side to GDN, other side to analog input plus 10K resistor from analog input to 5V.


From [u]Adafruit[/u]:

When no pressure is placed on the pedal, you'll read about 20 KΩ. When pressed down all the way, you'll read about 1 KΩ, and the resistance change is linear with the motion. Connect one side to ground, then the other side to a 10K resistor pull-up to your microcontroller's logic voltage. Then read the divided analog voltage, like you would with a photo-cell or other 'resistive' type sensor.

The top of page 4 [u]here[/u] shows you how to wire a photocell (or other variable resistor) with a regular fixed-resistor in series to make a variable [u]voltage divider[/u].

Except, the junction of the two resistors can go directly to the Arduino's analog input (no amplifier required).

Note that although the variable resistor is linear a voltage divider depends on the ratio so the output voltage is not linear.

Or, there is probably a regular potentiometer inside so if you can easily get it apart you should be able to bring-out all 3 wires and you can use it just like the [u]Analog Read Serial Example[/u], and that will be linear.