Help connecting old phone keypad.

I'm wanting to connect an old 3x4 phone keyboard to an Arduino as buttons and I need some help. All the stuff I've read online talks about having pins C1-C3 and R1-R4 but mine doesn't have that. Luckily the pins are labeled though. Link to picture: http://imgur.com/gallery/azXOG7Y

louisliv: I'm wanting to connect an old 3x4 phone keyboard to an Arduino as buttons and I need some help. All the stuff I've read online talks about having pins C1-C3 and R1-R4 but mine doesn't have that. Luckily the pins are labeled though. Link to picture: http://imgur.com/gallery/azXOG7Y

There is NO keypad, old or new, in that photo.

Paul

No, but there is a picture of the wires and how they're labeled (ie Mute, GND, DTMF, VDD, HKS, R1, X1, X0, and P0). I understand what Mute, GND, and VDD are. I'm just looking for some clarification on what the other wires are so I can eventually hook them into the pins in an Arduino board and use the keypad as inputs.

The row/columns reference is to the actual keypad arrangement. The keypad is decoded row by column via a dtmf decoder chip (there's a lot of those devices and what they actually do with the signal depends on the telco jurisdiction). In an case, the output from that device is the modulated DTMF signal, fed to "DTMF" on the pcb in your picture.

What comes next depends on what your use case is. If you wish to use the keypad wiring output to drive arduino inputs, then you'll need arduino logic to decode the row/column signalling from the keypad, and you'll need to disconnect the keypad wiring loom (not the ribbon cable in your picture) and connect to the arduino.

If you wish to connect the DTMF signal to the arduino and decode it, then you'd need to build logic to do that in the arduino, which I would not recommend (I've been a telco engineer for 25 of my 45 years career).

You can acquire a DTMF decoder on a chip, (device varies again on jurisdiction). You can usually match the decoder with the encoder on the pcb. Use the encoder chip part code to find it's matching decoder. This device will generally output a four bit binary coded decimal for the number 0-9, and BCD A,B,C,D (for a 16 key keypad) or A & B for a 12 key (standard telephone) keypad. * and # would be A, B respectively. That could be directed to the arduino either as 4 bit BCD and interpreted according to your use case, or you could multiplex the 4 lines to produce a serial binary code via a shift register.

All this is probably simpler than it sounds, but I thought a fuller explanation would get you going. It's going to be a fun piece of work and I'm happy to answer any questions along the way. I've built these things in the past, although we didn't have arduinos at that time so used period microprocessors - principles don't change.