LCD + keyboard matrix minimal I/O

[Jerson]

I was thinking if the 4 collom outputs could not be shared with D4-D7 from the lcd

I think you are on the right track. I see no problem if you use the LCD with 6 ports. Of these, you may use the 4 data lines as row outputs to the keyboard and use the RS line of the lcd switched to input to be a column when you scan the keyboard. You will need just one more line to make it a 4x2 matrix. Obviously, you will need to do a bit of juggling in the code to change modes when needed.

So, I think you can get by with a 6+1 lines to acheive what you want and NO ADC stuff is used yet.

Jerson