Upper Key Limit?

[degroof]

Not submitting as a bug (I've already written a workaround). Just curious...

I ran into an issue where the keypad library was working fine for a 6×10 matrix (i.e. 6 rows, 10 columns) but started giving phantom key codes for a 5×15 matrix. The symptoms were as follows:

• I would press a key and get a keypress event for that key.
• This would be immediately followed by 2 keypress events for a completely different key.

From what I can tell, this appeared to be due to something akin to a buffer overflow issue.

Is it possible there's an upper limit on the number of keys the library can scan? It seemed like the limit was somewhere between 60 and 75. I'm guessing 64.

Hardware: Adafruit Feather M0 Bluefruit LE (ATSAMD21G18).

[deHarro]

Hello @degroof !
Can you please elaborate upon your workaround?
I'm on implementing a 128 key matrix as control panel for turnouts at my model railroad.
Thanks!
Harald

[degroof]

I ended up writing my own scanner. Arduino source code is available here: https://www.printables.com/model/960905-bluetooth-membrane-keyboard-65-style/files

[deHarro]

Thanks for the fast response!
I'll try to dig into, but I think, it's over engineered for my application.
I have to detect switch states (not dynamically keys as at a keyboard for typing).
There are other comments on this library stating that increasing MAPSIZE would do the trick. I'll try that first.
Thanks anyway!