ZBasic Forum

I have a need to occasionally attach a 4 X 4 matrix keypad to a project. I would like to just plug it in somehow and be able to detect when the keypad is connected. I would just as soon not run an 8+ wire bundle to the project and have been searching for a ready-made, relatively cheap solution to sending the key presses to the project. Does anyone know of a ready made keypad-to-serial (or something) thingy that could get the job done? I don't want to spend time coming up with a solution if at all possible. The distance would not be far - a couple of feet max. I am attaching to a zbasic driven app.

Any enlightenment will be appreciated.

Vic

Vic,

I scanned the net for a long time a while back to find a device that took a PC keyboard and painlessly converted it to a simple ASCII serial data stream. Multilabs makes this device ( http://www.multilabs.net ). While you can conceivably do this with a ZX-24, why bother with the complexity of reinventing this wheel? Sadly, this does not directly solve your problem for a 4x4 keypad, BUT I mention it since many on this forum may be in need of such a device.

However, this device (Google "ABTPRO ASCII Backpack Matrix Keypad Encoder" ) does seem to address your dilemma with a 16 key pad. I haven't tried it, so you may have to report back.

Happy programming.

Dennis

How about something like this. I just glanced quickly at it, but it's an 8 bit digital I/O with an I2C interface. It would only need 4 wires, and detecting it's presence would be easy - if it doesn't respond to it's address, it's not there. The website looks old though. I have no idea about availability.


-Don

I found this today.

I vaguely remember it from a project about 6 years ago.

Thanks for the other suggestions. I will take a close look at all of these and see which is best.

Any further suggestions will be appreciated too.

Vic

The LM8333 has an I2C interface and can handle lots of keys. It is not too expensive, but it is not a "ready to use" solution.

Of course this could be solved by a dedicated slave ZX running the keypad interface and then communicating to the master ZX.

The cost of this would be the cost of the ZX and a few pieces of support components. I would expect this to show you the upper limit of the cost you should expect to spend on a solution. So, the $29 interface mentioned here is starting to get close to the upper limit.

If you have the capability to deal with a raw Atmel microcontroller, then you could solve this for something approaching the cost of the LM8333, but have the flexibility to program it to your specific needs.

-Tony