> 8x8 matrix. This would likely be the least hardware intensive method.
> The downside is that handling all the scanning and debouncing states
> might be a bit intensive. I suppose I could simplify it by just
> treating it like 4 independant 4x4 matricies. I've never done a matrix
> this large, it's a bit daunting.
> 
> Massive shift register. It would be easy to shift in 64 bits.
> Debouncing might be an issue though. At the very least this might
> simplify some of the board layout. Undecided on this one.

For ease of programming a SR chain seems top for me. You might want to
look at SRs that have a delayed output, to avoid clock skew problems.
You will need a pull-up for each switch. But an 8x8 matrix is only a
little bit more work. But you will need a diode on each switch to be
able to detect multiple key presses correctly.

For debouncing: just take care that you scan slower than the longest
devounce time (50ms is a good upper limit if the switches do not
document this). So with a 20 Hz scan frequency you can forget about
bouncing.

Wouter van Ooijen

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