The NeoTrellis INT line occasionally getting stuck low issue.

[lfg6000]

Bug Report:

The NeoTrellis INT line occasionally getting stuck low issue.

Reproduce Case:

I created a very simple reproduce case that is documented below:

Setup:

• (1) ItsyBitsy M4
• (1) NeoTrellis Keypad
• (1) Adafruit example code: interrupt.ino from the Adafruit seesaw Library\examples\NeoTrellis\interrupt\interrupt.ino
  (this Adafruit example code polls the neotrellis INT line (there are no interrupts being used on the M4...the file name interrupt.ino is a bit confusing)
• this reproduce case is 100% Adafruit example code
• using visual code v1.68.1 / platformio v2.5

Pictures:

This bug report was originally posted on the adafruit forum which included some pictures
https://forums.adafruit.com/viewtopic.php?f=22&t=192463

Test:

• press a kypd button a few times with the loop() delay set to 2ms.
• press a kypd button a few times with the loop() delay set to 50ms.

Results:

1. when the delay() in loop() is 2 ms the INT line does Not get stuck low
2. when the delay() in loop() is 50 ms the INT line Does get stuck low occasionally (anything >= a 7 ms delay() will cause the INT line to occasionally get stuck low)

Conclusions:

1. the length of the delay() in loop() appears to adversely affect the neotrellis INT pin's behavior
2. any code in loop() that takes longer then 7 ms to run will cause this issue to appear
3. this seems like a bug in the neotrellis firmware (ATSAMD09D14A see saw firmware)
4. this is a very straight forward way to reproduce the issue for testing and debugging

Hope this is helpful,
Louie

p.s. i have 13 of these neotrellis boards.
p.s. there is a workaround...detect when the INT line is stuck low and call NeoTrellis.SWReset()
p.s. i think Adafruit is awesome. I am very happy Adafruit customer. Your sw libraries make building so easy.