Button Matrix or DIN?

[wackazong]

Hello,

I found the C Example for a Button Matrix concept for MIOS. I have the same task, I need to scan at least 128 buttons (256 max) quickly with one core. Now I started wondering:

What are the advantages/disadvantages of that button matrix in comparison to using standard DINs for 128 Buttons (means 4 fully equipped DIN modules) regarding

- speed/performance

- accuracy (missed button presses)

- memory usage (on the same PIC, I want to do some I2C communication as well, if possible)

I looked around in the forums and in the wiki, but did not find much... There is the 16x16 matrix that QBAS developed, but I did not find a comparison to the old system of using chained DINs.

Thanks, ALEXander.

Thanks!

ALEXander.

[stryd_one]

- speed/performance

Fast enough :) You can change the update speed so it's up to you.

- accuracy (missed button presses)

Only if you press them really fast! See above.

- memory usage (on the same PIC, I want to do some I2C communication as well, if possible)

A slight increase but nothing that should stop the rest of your app from fitting.

Go with the matrix.

[wackazong]

Well, on second thoughts I think I will go with the "normal" solution nevertheless, because i can modularize it better.

With the normal input solution, i can put one or two 74hc165 on one pcb, together with buttons and leds, and interconnect them with just a couple of wires. for the matrix, I would need more wires.

Best, ALEXander.