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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If you don't consider a PIC a portable computing device, then what do you consider it?
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Well in this application I would consider it an ADC with an master I2C output.
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
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...