144 switches?

[Bill-D]

Hi all.

First project. Looking to send switch info over ble to a phone app. Switch would be a large keypad (custom built) with 12 rows and 12 columns. So 144 individual locations could be depressed. Im thinking rather than 144 switches, i go XY grid format. So a 12x12 grid. When seone depresses a key, it creates a closed circuit on a single row and single column. The coordinates are then in XY like in the game of battleship.

I have the arduino 101. How would I connect all 24 inputs? Or am I trying tl ise this hardware in a manner it is not intended for.

Thoughts?

[Grumpy_Mike]

How would I connect all 24 inputs?

Use two serial in parallel out shift registers and two parallel in serial out ones.

You will need a diode at each matrix intersection if you want to stop it all falling in bits when two or more switches are pressed.

Or am I trying tl ise this hardware in a manner it is not intended for.

This is a very conventional use of a matrix.

[Bill-D]

Great. Ty much.

[LarryD]

Crossroads was thinking of a 16X16 once:

Would you want to push more than one switch at a time?

[LarryD]

Here is an 8X8 I made up a while ago:

[Bill-D]

Larry, that's awesome. Thanks for the schematics. Do you happen to have a cleaner version? The image seems to be low res and is hard to read. No worries if you dont.

I would likely only need one "button" i.e. a single row contact and a single column contact per depression.

[LarryD]

Attached is a high res PDF you can download.
See image:

Root_1.pdf (36.3 KB)

[LarryD]

You may not want the top left-hand components:

[LarryD]

Here is a PDF version without the top left-hand leds:

EDIT:
Also attached keypad sketch .ino

Root_1.pdf (32.3 KB)

_64_ASCII_Keypad_Interrupt.ino (8.8 KB)

[CrossRoads]

Got it all layed out too.

[Bill-D]

Wow, thanks so much guys. Great to see such helpful people out there. Haven't played with electronics at this level since the NAVY and that was over 20 years ago. Cobwebs like crazy. Thanks again.