NP-41 Emulator (may be)

[Chris Chung]

(03-09-2016 02:56 AM)sa-penguin Wrote:  That keypad looks wonderful...
At the risk of derailing your work in progress, would you consider selling just the keypad?

If made as a USB style keyboard, I could probably plug it into my Nexus 7 Android, and use / make my own calculator app.
I could even arrange screen & pad independently, in portrait / landscape mode, as I see fit.

I assume you mean the keys PCB. It is not intelligent, more of just a physical matrix of keys and battery holder. There will be a lot of work to implement your idea.

An easy way is to pair w/ some known solutions that employs an MCU that has USB capabilities.

My keypad design, however, is not the common rows x columns layout. To save GPIO pins, they have additional multiplexing.

I am using 10 pins for the keys, w/ R x C layout, the most I can do is 5 x 5 or 25 keys.
Instead, I scan my 10 pins like so.

pin 0 scans w/ 1 2 3 4 5 6 7 8 9
pin 1 scans w/ 2 3 4 5 6 7 8 9
pin 2 scans w/ 3 4 5 6 7 8 9
pin 3 scans w/ 4 5 6 7 8 9
.... etc, this setup allows me to scan 45 keys.

If you like to try use this PCB, I can send one to you on shipping cost. Another idea is to install Fritzing and with my design file, you can add a ProMicro, or similar device (< $4) for a more complete solution.