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Author Topic: I need to convert PWM analog out to TRUE analogOut  (Read 2666 times)
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I'm trying to make an interface that controls the right thumbstick on an XBOX controller. I'm pretty sure they are analog and not PWM so now i need to figure out how to either get the PC to output true analog voltage or get a micro controller like my duemillanove to do it. I don't want to go out buying electrical components to make a home made circuit. there should be an off the shelf solution.
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yea, i measured it. 1.75 is center 2.20 is one extreme and i can't remember the other. can a digital pot be computer controlled (or controlled by a micro controller) off the shelf?
« Last Edit: September 23, 2010, 02:11:54 pm by David82 » Logged

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if its an XBOX 1 controller its around 5k
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Yes. You will need to know what resistance the thumb controller is, so you can get a digital pot of approximately the same value.
I need to disassemble the controller to make this mod no matter what. I have no idea how to find the resistance of the thumb stick though. it gets a max of 3v of power from 2 AA batteries and 1.75v is center. do you know the resistance based off of that info?
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Using a diode, capacitor and resistor sure seems easier to me than ordering a digital pot and waiting for it to ship to you.  You can probably do it with $3 of components from Radio Shack.
that sounds good too. i don't think radio shack has capacitors or diodes anymore though. what should I look for specifically?
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This 5K, 256 POS, SPI controlled digital pot looks like it's what I should use: http://parts.digikey.com/1/parts/483863-ic-pot-dgtl-5k-256pos-sot23-8-ad5160brjz5-r2.html

Here's a arduino tutorial for one similar: http://www.arduino.cc/en/Tutorial/SPIDigitalPot

the values for this pot are going to be changing very rapidly and very often. is the SPI interface still a good way to go?
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Uh oh, it looks like it might be 10K according to this: http://www.sparkfun.com/commerce/product_info.php?products_id=9032

so then this would be what to get: http://netsemi.com/p-246496-digital-potentiometer-ics-256-step-spi-10kohm.aspx
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there is not only 1 type of thumbstick in the world, yes playstations 1 & 2 use10k pots, the microsoft XB1 controllers use 5k (I have one sitting on my bench right now from a 100% microsoft controller)

then to put a twist in all this my logitech XB1 controller uses 100k, SO go get a multimeter and measure it cause if its 3rd party it could be anything, afterall they are just connected to a microcontroller inside the controller (fact on the microsoft design controller its a very small ATmega chip)
« Last Edit: September 23, 2010, 09:21:02 pm by Osgeld » Logged


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that sucks that everyone knows the resistance levels for everything except the XBOX360 POT. I'm pretty sure it is 10K since the guy in one of the tutorials replaced his with the 10K pot from sparkfun.
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if you can measure voltage ... why cant you measure the resistance?

(and "some guy" did it does not mean it was correct)
« Last Edit: September 23, 2010, 11:24:27 pm by Osgeld » Logged


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i don't know how. i see it on the multimeter. i guess i put it on 20K since that is the closest setting to 10K but then what? do you measure it the same way you would voltage? or so you do it with the board powered off where by it uses the multimeter power? who knows...
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i guess i put it on 20K since that is the closest setting to 10K

yes

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you do it with the board powered off where by it uses the multimeter power?

yes

there are 3 pins put a probe on the outer 2

If I was messing with it I would go with Richards suggestion, the pot is just acting as a voltage divider, you can take a pwm signal, run it though a low pass filter made out of a couple passive parts (that yes radio shack sells at your local mall) and just stick it where the middle pin is and the controller would be none the wiser
« Last Edit: September 24, 2010, 12:12:21 am by Osgeld » Logged


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ok so where do the 2 leads go? in the attached picture mark 1 and to are the pot leads. if i had to guess the red lead on the voltmeter would go on either 1 or 2 and the other lead from the voltmeter would go on ground.. or maybe positive?
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read my last post I edited it
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If I was messing with it I would go with Richards suggestion, the pot is just acting as a voltage divider, you can take a pwm signal, run it though a low pass filter made out of a couple passive parts (that yes radio shack sells at your local mall) and just stick it where the middle pin is and the controller would be none the wiser

OK, i can do that if you can give me much more specific instructions. in the pic at the bottom, labels 1 and 2 are where the voltage changes as you move the stick. If you could draw out a wiring diagram with the parts labeled I should be good to go.
« Last Edit: September 24, 2010, 08:53:05 am by David82 » Logged

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