I have been working on this problem for almost 2 wks. I have built a LED matrix, and have a USB keyboard that plugs into a USB Host device that does I2C to Arduino. This works fine on Uno/Mega,
it does not work on Due. I have confirmed that IDE is getting the right libraries for wire.h.
I’ve read that their where problems with wire.h I2C on the Due. I’m running the latest version of IDE
these should all be fixed. Also I have I2C connected to pins 20 and 21. Again the exact code will work
on Mega. Also, I have a new Due R3.
long_signboard_broken.ino (17.7 KB)