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.
Steve
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.