Best posts made by y4CdW42Ol8

Hello All,
Everything is working… The problem was that the Arduino DUE puts out SCL and SDA on pins 21 & 20, respectively.
Thank you.

Problem Solved! When compiling, you must select Processor: ATmega 328 (3.3v, 8Mhz). Then the Serial Monitor will be fine at 9600 baud with the 3.3v Pro Mini.