i ordered the free samples for the x/y controller. 1 week later i got mail. a personal letter, and 2 touchpad like things.
As an inexpensive and customized substitute for the traditional finger-actuated laptop mouse pad, the XY pad is used in varied applications. Though most companies can meet their position sensing needs with a one-directional sensor in the Soft Pot potentiometer, some demand dual-axis feed-back, and the XY Pad does just that.
Based on resistive carbon technology, the XY Pad feels and acts like a mouse pad, giving an operator the ability to track position feedback according to the motion of his/her finger.
The XY Pad produces two simultaneous and contiuously variable analog outputs. One output represents the X position and the other represents the Y position. As you move from one position to another, a different set of XY analog values is produced.
if it puts out an analog voltage for both axis (which i think is the case), it can be used as a potmeter/joystick ;D, you just have to make it in the 0 to 5V range for midibox applications if it isn’t allready ,and connect it to a AIN module.
do you have a datasheet of the pad, to see what voltages it outputs, how to connect it etc? they don’t have technical specs on the website yet.
nope, no specs they just send me 2 of those touchpads and information wich is also located at their website. i also tried to messure the resistance with my multimeter. if i touch it, there is a resistance wich increases when i move my finger into a direction.
i’ve requested a sample of the x/y pad and the softpot. i havent done any tests or readings with them, but from the papers they send, they seem to me to be like “normal” potentiometers. they dont send any voltages. but they can be used as regular pot’s connected to AIN modules, but they dont save positions. i’m going to do the tests and let you guy know the results.
i’m planing to use them on 2 diferent projects, one is an electro theremin , were i’ll use the softpot (a ribbon controller for the frequency) and the other on a Filter module to control the resonance and frequency ( x/y pad).
I’ve tested the Softpot, and they extremelly cool for making a ribbon controller! they have 100Kohms and 6’ long (26cm). The X/Y Pad … thats another story… since they dont have a datasheet (at least i couldnt find one on theyr website, but i’m requesting the pinout of the pad) i cant figure the way it works… they sended me some flyers talking about the x/y pad and there was a pic with the simbols of 2 variable resistors and 2 pushbuttons, but since there are 7 pins and no pinout i couldnt (yet) figure it out… i’m going to request the datasheet or pinout to the seller.
For use with midibox… the softpot doesnt seem very good…since its always off until you touch the pot, then according to the place you press it gives you a resistance. If you touch the beggining it reads 0 ohms and the end 100kohms, if you slide your finger the readings go up and down, just like a ribbon controller. I’m not going to use it on the midibox project, but instead i’m going to build an electrotheremin using the ribbon controller to control the pitch and a simple pot for the volume.
I don’t have my notebook in front of me at the moment, but I managed to get the touchpad working on the bench. Seems to have less resistance than the softpot’s (which are VERY cool) and also seems that there are two “buttons” under the pad itself, which explains the extra leads. I contacted a sales rep about the softpots, ~9$ each for an order of 100, price drops quite a bit around 500, 2.50$ (US) if I remember correctly. With the proper drivers and some good visual feedback these could make a slick replacement for MF’s.
The main problem using the softpots is the position memory, that doesnt exists… with a fader you have a mark telling you were the resistence is… with this one, theres no such thing. perhaps theres a way (software) that memorize the value in the PIC and when its touched again it changes…but without visual indication (a led bargraph would help telling you the position) is going to be a hell…
if we could get a way to show the position in a led bargraph would be sweet… imagine a fader without knob and a bargraph showing the place were the knob would be
regards
p.s. moogah…when you have the pinout let me know to compare, i’ve been able to find the switches but seems that the resistance of my pad is about 2Kohms… did you get thoses readings?
very nice. i also figured the same out, the xypad act like 2 pots. isnt it possible, to do that ‘save position’ stuff via software ? maybe, it always saves the last value, then you touch the pad, the pot gets active, and sends a new resistance to change the value.
For the softpots I was thinking of software that ignores the absolute position and only listens the the change in signal, so that If you slide up it increments the value, sliding down decrements the value, reguardless of where you touch the pot.
wow, that would be great. my asm skills are too bad to think about doing something like this myself for now. hope you get it and publish the code. thanks in advance man.
Well… I’ve never coded .asm… but I am rather cocky about code in general. I will DEF publish anything I come up with for the MIDIBOX in general, I’ve got some sequencer grooves from some funky breaks I’d like to add to the sequencer, along with a full seq app specialized for 808/909 style drum programming I’d like to realize on a MIOS base.
The spectra pad consists of 2 resistors, each of imp about 1KOhm. You can build a simple voltage divider - the only con is that You need more than 5V as the input (my PSU delivers 5 and 12V)
                 Â
   Vin–???---------?-----------Vout
        R1-pad   ?
                  ?R2
                  |
                  |
                 Gnd
Vout=Vin[R2/(R1+R2)]
Assuming Vin=12V, R1=1K and Vout=5V You get R2=450Ohm
You will need 2 of those circuits for x and y axis.
But I’m not sure if this will work (loaded voltage divider - Thevenin’s theorem???), waiting to have some spare time to check if it works in practice.
It seems that it won’t be so easy… In fact You don’t get diffrent resistance values for x and y. Peel off the adhesive paper from the pad and You will see why… There are 2 ‘sheets’ of that carbon resistive material placed one over the other, each with 2 connectors on the opposite side. Pressing in some point makes the 2 sheets touch each other.
When You connect a multimeter, You will get values from “upper-left” connectors and “lower-right” connectors. Connecting one sheet (ex. upper and lower pin) makes the multimeter show 0,5 KOhm - impedance of one ‘sheet’.
When connected pins are lower and left, in this corner You get 0,5KOhm. Diagonal is the line of constant impedance equal 1KOhm. In the upper-right corner of the pad You get 1,5Kohm.
The other connector behaves simmilar.
The idea with voltage divider may work, but additional impedance buffer may be needed.
I’ve received the samples from SpectraSymbol : very nice piece of hardware !
I’ve connected it to the AIN : it works great to transmit values from 0 to 127 but it flickers a lot around 64 when you don’t touch it :'(. I have many oher devices attached to other AIN pins (pitch bend, modulation wheel and two joysticks) and none of them flickers that way. ???
Do you have any idea ?
Thanx for help, I’d really appreciate to use this as a ribbon controler for my midibox …
they just send me 2 of those touchpads and information wich is also located at their website. i also tried to messure the resistance with my multimeter. if i touch it, there is a resistance wich increases when i move my finger into a direction.
