Newbie question: Matrix scan order and diode orientation

Unfortunately there is no common place to find every information possible, Google is your best friend.

Pic A is the correct way to do.

Pic B will not work.
For example for Col5 pin, the signal will have to travel through 5 diodes, each time with an associated voltage drop. That translates to 5 x 0.6V = 3V, meaning that the rows will never see any high signal from this col.

2 Likes