·I have not used this forum before, I trust I'm in the right place.
I could not find any information on a 12 Button Keypad and would like to know if anyone has Prop code to work with a 3K12T203 — STORM INTERFACE — Keypads.
I remember a couple other threads of people asking questions related to matrix keypads. You can use a search.parallax.com to search the forum to find those threads.
How will you be attaching to the keypad? Will you use pullup or pulldown resistors? For the Prop Blade PCB I did a matrix that was 3 "rows" by five "columns". I was reading DIP switches and tactile switches. The row and columns were attached to I/O, 8 total I/O. The columns also had a pullup resistor on them of 10K ohm. The rows are set to be inputs (high impedance). The row that you want to read is then set to a low output (0V DC). The column inputs are read. Note that the inputs will be 1 when they are not pressed and 0 when they are pressed. Then the row output is changed back to an input and the next row is done.
I was reading 308 circuits they had a simple circuit for reading 4 x 3 matrix pads with only 4 IO. It used diodes connected diagonally. I found the book in google books - Here's the link
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Welcome Frank, There's yet another way to read a matrix keypad with minimal pins. It uses resistor dividers between the rows and columns so each key press results in a different analog voltage. I posted a drawing somewhere in this forum but can't find it (search is difficult in this forum IMHO). The circuit may be more useful in uControllers with built-in A/D's, propeller has none but can do delta-sigma A/D with a handful of extra parts, but the pin count would probably not rival the diode method mentioned by Nick when using propeller.
Comments
There is code in the Object Exchange for a 4x4, perhaps it could be easily adapted?
obex.parallax.com/objects/279/
OBC
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I remember a couple other threads of people asking questions related to matrix keypads. You can use a search.parallax.com to search the forum to find those threads.
How will you be attaching to the keypad? Will you use pullup or pulldown resistors? For the Prop Blade PCB I did a matrix that was 3 "rows" by five "columns". I was reading DIP switches and tactile switches. The row and columns were attached to I/O, 8 total I/O. The columns also had a pullup resistor on them of 10K ohm. The rows are set to be inputs (high impedance). The row that you want to read is then set to a low output (0V DC). The column inputs are read. Note that the inputs will be 1 when they are not pressed and 0 when they are pressed. Then the row output is changed back to an input and the next row is done.
The object is here and should be adaptable to what you are doing: http://obex.parallax.com/objects/341/
I clicked over to Digikey to see more details about the part. That part looks very beefy and good for industrial use, what are designing?
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Timothy D. Swieter, E.I.
www.brilldea.com·- Prop Blade, LED Painter, RGB LEDs, uOLED-IOC, eProto fo SunSPOT, BitScope
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www.tdswieter.com
Here's a link to some info about the Storm Interface keypad, including a link to a datasheet.
http://www.storm-interface.com/product_attachments/3000Series.pdf
It looks like a regular 4 X 3 matrix style keypad.
Here's a link to a site that has some generic information about reading and using matrix style keypads.
http://www.elexp.com/t_keypad.htm
Good Luck
B-
Post Edited (Brian218) : 7/30/2008 6:49:50 AM GMT
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Concentrate on understanding the problem, not applying the tool
David