I've a problem with my Arduino Micro and the Keypad library.
The circuit works great if you press only one button per time.
The problem is when you press more than one. Diodes are already there.
Here's the schematic of the circuit:
As you can see, when one of the inputs of the AND port will go down, then the transistor will close the circuit between row and colum.
I can share the code if you need.
Thank you in advance.