Hi Guys,
Id like to interface a microcontroller directly to the keypad of a mobile phone.
The mobile phone is dedicated to the project, and is disassembled so that the
keypad contacts can be directly soldered to.

Since the phone has a matrix keypad, I can't just use simple transistor switches to
complete the button connections, as the transistors won't share a common ground.

I'm looking for ideas on how do do this without using the Nokia FBUS/MBUS protocol.
Cheers, Art.

 

You could use bilateral analog switches to connect the matrix points.

 

Thanks, I think that will do it:
http://www.jaycar.com.au/productVie...d2=&pageNumber=&priceMin=&priceMax=&SUBCATID=