Driving a keypad

Hoon

I have a Data Entry terminal which I would like to automate some data entry using the BS2.

The terminal is driven by a keypad in a·4x5 matrix.· To operate the keypad, the bs2 needs to connect one of the 4 column pins to one of the 5 row pins to simulate a button press.

The BS2 and keypad are isolated from each other (i.e. not sharing the same +ve, gnd) so I'm guessing some kind of relay solution is needed to close the pins but I'm not sure how I can acheive a·"one to many" relay relationship without setting up 20 (4x5) relays.

Does anyone have any ideas or maybe a better solution?

·

Mike Green

What you're suggesting (20 relays) is pretty much the only solution that would keep the Stamp and the data entry terminal isolated from each other and would not require you to delve into the internals of the data entry terminal. Reed relays would be the smallest, fastest, simplest way to do it.

Optocouplers could be substituted for relays, but would require you to figure out how the keypad is used internally since the polarity of the wiring would be significant.