Hi, newcomer here. Glad I found this awesome board.
Because of stick drift in my 1697 controller model I replaced the stick pots with hall effect replacements.
https://www.ebay.com/itm/355351310821I noticed that new sticks are now slightly off-center. But what's even worse: The controller reports full axis value when the stick is only deflected about 50% of max travel. I guess this is due to factory calibration of previous pot values which are stored in the microcontroller (MKL26Z256VMC4).
I measured in-circuit range of the hall effect "wiper pin": 0.2V - 1.7V. According to my measurements the stick range should be somewhere at 0.4V - 1.4V. for -100% .. 100%. 0.9V for center position.
I wanted to do a new calibration, but I don't know how. I cannot use the XBOX Accessories App, neither upgrade the firmware because the upgrade always fails, but the app says "upgrade required". The launch option with firmware downgrade also doesn't work. I guess the controller still has its original firmware. I never updated it.
Can you confirm this wiper pin voltage range (0.4V .. 1.4V) for the standard pots?
Do you know any possibility to calibrate the new range (0.2V .. 1.7V)?
Do you have the test point designators for the JTAG interface of the MKL26? I would give it a try to reverse engineer the firmware and see where calibration values are stored in memory. Maybe the chip is not protected.
If the MKL26 is protected the only possibility I see is adjusting the wiper range using an opamp voltage translation mod. Or maybe there is a possibility for a side-channel JTAG attack.
