keypad

blink13

i have been wanting to make an electical lock using an old fone keypad but, im not sure how, ive takin the keypad out of the fone and the port for it, but i cant tell wich button is wich string of metal on the plastic band that goes fromt eh keypad to the port

Paul Baker

If you have a multimeter (if not you should get one), you can determine the keypad organization. Keypads are organized in matrix format like this:

               
                  |      |      |  
                 .-.    .-.    .-. 
               -( 1 )--( 2 )--( 3 )
                 >-<    >-<    >-<  
               -( 4 )--( 5 )--( 6 )
                 >-<    >-<    >-< 
               -( 7 )--( 8 )--( 9 )
                 >-<    >-<    >-< 
               -( * )--( 0 )--( # )
                 `-'    `-'    `-' 

so there are·3 column lines and 4 row lines, when a key is pressed the row and column corresponding to the key is electrically connected. By using a multimeter and testing which lines are connected when you press the button you can determine which wire is which. Then find an NV article or helpfile which has example code.

Post Edited (Paul Baker) : 4/21/2005 2:39:48 AM GMT

blink13

ok, i figured out how, i probably didn't think of this last night because i stabbed myself in the hand with a skrewdriver and was in alot of pain, im gonna run a old program fomWHAT IS A MICROCONTROLLER to determan the key order.

blink13

no that didn't work im almost posetive this keyboard has doesn't work cause it is from the 1960's

Forrest

Did you use a multimeter to determine which keys are connect to each pin on the connector? This is the first thing you need to do because you can't write a program to read the keys until you determine how they are wired. Another alternative is to puchase a keypad that includes a wiring diagram - such as this one www.parallax.com/detail.asp?product_id=27944

If you search the web, you can find less expensive alternatives. I recently picked up a project case with a 15 button keypad from Radio Shack a few days ago for $4.99 - P/N 270-215. This was a discontinued item - which is why the price was so low. I was able to connect the keypad to a BS2 using a circuit similar to the one listed in Nuts & Volts #22 (which you can download from Parallax) and I modified the program to read the keypad.

blink13

yes i used a multimiter, do you think buying a memkey and a 4x4 matrix keypad from parallax

Paul Baker

Here is cheap source, or just find another junker phone.

blink13

oh tnx cause my alternative was a 20$ allied keyboard

SK8 4 U

Try Digikey...they have lots of stuff like that.

Joe

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