Richard, I just took a look at your code; WOW! Well Commented!!
I'll have to spend a bit on Google to figure out how you stitched that all together :)
I put my rig together in '15, but converted it to VFO in 2019 as a learning project.
The programming is pretty basic; VFO, frequency step (10K, 1K, 100hz) ,and the Arduino monitors the straight key which keys the Fourty-9er,
, Ron WB9YZU