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creating a joystick (oh joy)
I have, getting tired of searching for 3d joysticks that use serial instead of USB, decided to build my own 3d joystick and I was wondering if anyone has a recommendation for high quality potentiometers. I'm aware that they become uncalibrated over use and I'm looking for something easy to reset and reasonably reliable. One thing I'm considering is mounting a normal joystick to a swiveling surface and attaching one potentiometer to that.
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Re: creating a joystick (oh joy)
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paying around $10 for a very nice Bourns unit if you want. The most significant problem for building a joystick is the mechanical lingage. This is where most of your effort would be focused. Have you considered buying a USB joystick and then gutting the electronics? All you would need to do is find one that uses 100K pots internally, custom wire them to suitable inputs on the OI and then you would be done. Any centering adjustments could be handled by putting a lower resistance pot in series. Alternatively, you could use a switch input to the OI to command the RC to read the pots and use that value for "center," taking one more adjustment that can get messed up out of the equation. Eugene |
Re: creating a joystick (oh joy)
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Re: creating a joystick (oh joy)
the problem is i really want to use a 3d joystick.
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Re: creating a joystick (oh joy)
Well, if you can get quadrature output, or a analog voltage, you could use a PIC and an SPI digi-pot. The SPI protocol is simple enough to bit-bang, and there is 8-bits of resolution, which lines up nicely with the OI.
Of course with that, you could start getting into look-up tables allready on-board the joystick, on-board mixing, and all kinds of fancy stuff... Got a kiwi drive? use the PIC to mix your 2 joysticks, and send the desired motor values to the RC, which can still use PID or whatver kind of control you use. I may develop a simple PIC based converter this summer, if I do I'll make the source code available for use, and sell pre-programmed pics with the code on it. Though if you want to get fancy, it might be neat to use the force-feedback on a sidewinder for something. Maybe a stick shaker or somthing if the CG is in a bad position, (robot about to tip...) or make it more stiff going forward if it detects that the wheels are slipping, (I.E. you are shoving something) |
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Many alternative joystick solutions are being posted in this thread, you might try looking there. |
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Good luck. EDIT: That Q&A answer really suprises me...I guess you'll just have to go by whatever FIRST says next year. |
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Re: creating a joystick (oh joy)
If you don't consider a PIC a portable computing device, then what do you consider it? You can move it around (it's not bolted to the floor or anything, so it's portable), and it computes stuff. It isn't one in the traditional sense of the word, but in terms of FIRST, it may be iffy. This is one of the issues where it's the intent of the law vs the wording of the law. Try to understand what they want to avoid and see if what you're doing opens up the possibility.
Gotta ask: what are they worried about with a logic driver of some sort connected between the joystick and the oi? Sparks |
Re: creating a joystick (oh joy)
I also believe a PIC is a portable computing device, I'm not sure what else you classify it as, so in that sense, it wouldn't be legal. However if somebody can point out a way to classify it that's not a portable computing device, then I suppose it'd be legal in a loophole sense.
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Re: creating a joystick (oh joy)
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Well I was thinking some more, if you got tricky, you could partially bias on a FET to get the varying resistance. But that would have to be tuned to each individual FET, not just for one type, since each one would be slightly different.
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I guess if you had to you could use a parallel ADC, a parallel in serial out shift register, a 555, a spi digi-pot, and some more logic, but a PIC would be so much easier. Just a pic and a digi-pot. Wait a minute, you might be able to get away with just a parallel ADC. With various resistors on the output. Let me do some thinking about that and get back to you all. EDIT: I got it :D Take an 8-bit or greater ADC, provide it with whatever it needs to keep spitting out values, put an octal inverter on its outputs (the 8 MSBs if it is > 8 bit) and have the octal inverter outputs hooked to the gates of some small MOSFETs. Have it so when that particular mosfet is on, the total resistance of the mosfet and the resistors on it is equal to what is in the calculator spreadsheet I attached. 10k-90k is a reasonable range for one of the CH flightsticks right? if not you can change it to whatever is you like. The calculator accounts for a pull up resistor of the same value of the maximum pot value. You might be able to get away without the mosfet stage if you are using a inverter with CMOS outputs, but I'm not sure. It would be nice if we could get someone that would pre-make these and be able to sell them to everyone. Just a little box thing that goes on the end of the joystick cord. Wouldn't be that hard, just get some PCBs made up by www.olimex.com, get the the DAC's and the other components and solder it up. Is Andy Mark up to expanding into electronics? ;) EDIT 2: bah, I dont think I have that spreadsheet right. I need to work on it some more... |
Re: creating a joystick (oh joy)
Gotta say it again:
What is the intent of the rule, and is what you are planning on doing opening up the possibility of what the rule excludes occuring? Personally, I have absolutely no idea what the intent is. Any thoughts? Sparks |
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