Arduino2Max Force Sensitive Resistor - where is the issue?

Hi Arduinoers

I am trying to solve a what I'm sure is a very basic Arduino2Max problem. I have a force sensitive resistor connected, via a breadboard, to an Arduino BT w/AT Mega 328. I had spent a lot of time just getting the program loaded onto the Arduino, but seem to have finally managed that now. I have uploaded the arduino2max.pde file to the arduino . All I would like to do is read data from Analog port 0, and have this displayed on the standard max patch.

Can anybody see where I am going wrong? I believe that the set up of the breadboard is correct, but if you would be so kind to double check then that would be fantastic - this really isn't my area of expertise. I am not sure at what stage of the project the problem is occuring - it could be that the breadboard is fine, but interfacing with max via bluetooth is the issue.

I am using a 10k ohm resistor. I also changed the last line of the programming code to Serial.write(32); as it Arduino could not understand 'BYTE', although I am not sure what the best value to put in here would be. The max patch has the serial reader linked to ARDUINOBT-Bluetoothseri and the correct port has been selected. I am at my wits end as I'm sure it's a small issue that I am overlooking!

Also worth a look - this is the circuit that I am trying to follow: http://www.ladyada.net/learn/sensors/fsr.html (the part titled analog voltage reading method).

I have tried attaching an image of the breadboard but it wont upload for some reason - perhaps if someone could tell me how to do this, then it can shed light on the breadboard set up I have going on.

Again, any help would be massively appreciated.

Thanks for your time

Armagideontime

Here is a link to the image shack photo:

http://img24.imageshack.us/img24/646/photo1rxp.jpg

I have the 9v terminal connected to the left leg of the FSR. the right leg is connected to a 10 kOhm resistor, which is connected to ground. the right leg is also connected to analog ).

I have the 9v terminal connected to the left leg of the FSR.

The 9V terminal of what?

the right leg is connected to a 10 kOhm resistor, which is connected to ground.

Why do you have another resistor? Use a meter to measure the resistance across the outside legs. Measure the resistance between one outside leg and the middle leg as you apply pressure. The outside resistance should not change. The middle to outside resistance should.

the right leg is also connected to analog ).

The FSR should be like a potentiometer. One outside leg is connected to a voltage source. The other is connected to ground. The middle pin is connected to the analog pin.

PaulS, thanks very much for lending your ears - it really is appreciated.

Firstly, a massive error in that original post: I had meant to say 5V instead of 9V, as in the 5V terminal from the Arduino BT supplied from the battery pack.

I was using another resistor as I was following the other tutorial (link above)... however, without having a full grasp on the circuits perhaps this is not the best tutorial to follow. The FSR I am using is this: http://www.coolcomponents.co.uk/catalog/force-sensitive-resistor-square-p-566.html ... As far as I'm aware this only has two legs. So now I am very confused!! All i am trying to achieve is a max patch (I'm using the standard Arduino2Max max patch) that reads an analog value from the Arduino, representative of the pressure exerted on the FSR. thus far no luck!!

Any further thoughts/ideas would be excellent.

Thanks a bunch

Armagideontime

OK. That is not a potentiometer style resistor. You do need a second resistor. One leg of the FSR connects to 5V. The other leg connects to another resistor and to the analog pin. The other end of the resistor connects to ground.

  • ---> FSR --->*---> R -->- GND

Run a wire from the junction (*) to the analog pin.