How would I go about interfacing an arduino with an old joystick from a wheelchair?

I have obtained a joystick module from an electric wheelchair.  The board says DYNAMIC CONTROLS (C) Mar 2011 GPC80830 REV E.  On the underside of the board, there seems to be test pads labeled the following: +5, MOSI, SCK, MISO, RST.  Slightly to the right of +5 is a test pad that says 0V.  Below are pads labeled SBL and SBH.  Slightly more to the right of 0V is a pad labeled SB+D.  Finally, furthest to the right are test pads BCN, BC, and BCP.  On the top side of the board there is an ATMEGA8A AU 1114 Micro-controller and an empty 5 pin through hole connector.

Also soldered onto the board is a joystick that consists of a coil and 4 smaller coils soldered to the board in a + configuration around it (Some sort of EMF sensors?), a weird 4 pin connector and a 3 pin programming port resembling an XLR connector.

Any ideas?

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gpotvin (author) 4 years ago
Here is a basic drawing of the underside of the board from memory. I will post a picture later. Hopefully this will suffice for now.
The 5 pin through hole is for in circuit programming of the Atmega8.

If you know how to reprogram Atmega8 with Arduino you can.

gpotvin (author)  Josehf Murchison4 years ago
Its already programmed but the question is can I do anything with the program on the board and if not, then what can I do?
Do you want to read the program on the IC and adjust the program on the IC?

If you do, it can be done, it is not legal in most places, copy right protection and the IC is built to prevent you from doing just that in circuit, but it is not impossible. To do it you will need to remove the IC from the circuit board or disconnect the IC on the board and Hack into its files.

Once you hack into the files you can copy the files however they should be hex files, unless you can write in hex you will have to convert them to C++ or Arduino, make the adjustments and reprogram the IC.

Easier to erase and reprogram the IC with your own program.

From your description the IC is built for in board programming so that erasing the programming and reprogramming should be quite easy.

The other thing you can do is connect up the circuit and see what it does.

gpotvin (author)  Josehf Murchison4 years ago
Wasn't planning on using it for anything commercial, so technically it's not copyright violation. I might take a look at the program just to find out how it works. It might shed some light on the subject. The issue is that it's a straight 5 pin header without labels. I wouldn't know which pins to hook up to the ISP.
This is an arduino sight that may be able to help you:

You can get the datasheets here just put Atmega8A in the search box:

gpotvin (author)  Josehf Murchison4 years ago
So basically there is no easy way to utilize this piece without dissecting the program on the chip...
I think Arduino can read it, I mostly work with pal and Pic the programming is basicly the same, when it comes to Arduino I'm new I got my Arduino just to play.
rickharris4 years ago
Your going to need to supply the joy stick with + 5 volts and ground (0 volts) and measure a few things.

gpotvin (author)  rickharris4 years ago
I tried that on the multimeter. Did not produce any discernible output. Maybe some kind of serial interface (besides +5 and ground) for the test pads?
Pictures would helpful.
gpotvin (author)  mpilchfamily4 years ago
basic diagram posted