Is it possible to filter out certain (faulty) button inputs?

Clyde

Hi,

both of my DragonRise zero delay encoders (one more often than the other) have a glitch from time to time on only one button port that sometimes creates absurd values like 16552, 32767 or even negative numbers of type 2. Normal button presses have the type 1 value 1, so it came to my mind to somehow filter out all other values. Ideally, it should work system-wide so that neither ES nor its screensaver or any emulator registers these values.

Does anyone have an idea how to achieve this? Mind the different event type of the ghost inputs. edit: According to the joystick API documentation, type 1 means "button pressed/released" and type 2 means "joystick moved". So, I need a way to filter out joystick movements but let button presses through.

$ jstest --event /dev/input/js1
Driver version is 2.1.0.
Joystick (DragonRise Inc.   Generic   USB  Joystick  ) has 7 axes (X, Y, Z, Rx, Rz, Hat0X, Hat0Y)
and 12 buttons (Trigger, ThumbBtn, ThumbBtn2, TopBtn, TopBtn2, PinkieBtn, BaseBtn, BaseBtn2, BaseBtn3, BaseBtn4, BaseBtn5, BaseBtn6).
Testing ... (interrupt to exit)
Event: type 129, time 1247460, number 0, value 0
Event: type 129, time 1247460, number 1, value 0
Event: type 129, time 1247460, number 2, value 0
# rest of initialisation lines removed
Event: type 2, time 1451440, number 2, value 32767 # here be dragons
Event: type 2, time 1451450, number 2, value 0                                                                                                                                                                                                        
Event: type 2, time 1617270, number 2, value 16552 # here be dragons                                                                                                                                                                                                 
Event: type 2, time 1617280, number 2, value 0     
Event: type 1, time 2826590, number 2, value 1 # normal button press                                                                                                                                                                                                       
Event: type 1, time 2826710, number 2, value 0

edit: Oh, and it's neither the button nor the cable, I changed all of them and the effect remained on port 2 of the decoder.

Thanks in advance
Clyde

mediamogul

@clyde

Are the joysticks analog? It sounds like an overly sensitive deadzone problem.

Clyde

@mediamogul No, the joysticks have digital microswitches. I noticed an error in my reasoning: The buttons have nothing to do with the problems, as their ports are generating type 1 events. Only the joystick ports on the decoder board (four for each joystick, one per microswitch) generate type 2 events.

That said, the joysticks' microswitches are connected to the ports for axis number 0+1, whereas the ghost inputs only come from axis number 2, which nothing is connected to.

I tried to set the dead zones of axis 2 on both joysticks to its whole range of -32767 to 32767, hoping that would lead to the driver ignoring them alltogether. After that, jstest doesn't show any input from them anymore, but the screensaver still recognizes some input in irregular intervals and quits back to ES.

$ jscal -s 7,1,0,127,127,4227201,4194176,1,0,127,127,4227201,4194176,1,10,-32767,32767,2147483647,2147483647,1,0,127,127,2147483647,2147483647,1,0,127,127,2147483647,2147483647,1,0,0,0,2147483647,2147483647,1,0,0,0,2147483647,2147483647 /dev/input/js0
$ jscal -s 7,1,0,127,127,4227201,4194176,1,0,127,127,4227201,4194176,1,10,-32767,32767,2147483647,2147483647,1,0,127,127,2147483647,2147483647,1,0,127,127,2147483647,2147483647,1,0,0,0,2147483647,2147483647,1,0,0,0,2147483647,2147483647 /dev/input/js1

The part for axis 2 is 1,10,-32767,32767,2147483647,2147483647, see jscal's manpage for more information.

I got this idea after some research, from these two sites:

https://ubuntuforums.org/showthread.php?t=1079284 (a similar problem to mine)
https://blog.gimx.fr/joystick-calibration-in-gnulinux/ (it explains the working of jscal -s in some more detail)