hello all...
is that any information of keypad using the mplab write one...
i'm a newbie and no use this software before.
can anyone show me some easy code for the keypad.
because i don't know is that correct or not when i reseach from the website...

thx for helping

 

hi,
Look at this site:

http://www.winpicprog.co.uk/

Or here:

http://www.tundraware.com/Software/PIC/keypad/

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

if i using the IC 74C922 is that i can save a lot of time for write software??

 

how about using the IC74C922 ??
is that any problem when using the IC74C922 send data to the PIC16f877??

 

You can use the IC74C922 if you want. You don't need to because the PIC can do it all by itself as mentioned on the pages posted by Eric.

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ya i know.
but the thing i want is use the keypad combine with the PIC and get the output to control other thing.
is that i can use IC74C922 combine with the PIC then get the output from PIC?

 

Yes, you can do it either way - it all depends on which you prefer (and on what keypad you have).

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

hi,
A 74C922 can simplify your program.
Basically it scans a 4 * 4 keypad matrix, giving a output nibble 0 thru F [4bit]
also a another bit goes high to say a key has been pressed, use that for the Interrupt.

If you live in the UK, I'll send you one, FOC.

Attached Images

screenhunter7.jpg (46.4 KB, 66 views)

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

It's available here but this is one of my favourite PIC Tip & Tricks (there are many more on the Microchip site in the app notes section. There's a section on a 4x4 keypad in there.

Attached Files

PIC Tips n Tricks Hardware Techniques.pdf (488.5 KB, 84 views)

__________________
Bill
Smart Kits build Smart People
http://www.blueroomelectronics.com

 

I like the resistor keypad idea. Here the 74c922 costs more than the pic itself

 

Here too, and it's easy to do in software.

__________________
Bill
Smart Kits build Smart People
http://www.blueroomelectronics.com

 

thx a lot for all helping me in here.....

 

i have a quetion for the IC74C922....
is that i press the button '0' the output will become "PA=0,PB=0,PC=0,PD=0"
then i press the output '1' will become "PA=0,PB=0,PC=0,PD=1" and so on..>??

or is other else?

 

is this correct??

#include <p16f877.inc>
PortB equ 06h
out_put MACRO var
movwf PortB
bsf PortB, var
bsc PortB, var

movf h'0A', w
out_put 4
movf h'0B', w
out_put 3
movf h'0C', w
out_put 2
movf h'0D', w
out_put 1

ENDM
END
thx for helping

 

hi,
If you look at the TRUTH table as part of the 74C922 diagram I posted a few days ago, it will answer your question.

Summary:
the answer to this question is, for the #1 key, A=1,B=0,C=0,D=0,[you have reversed the pattern!],
also a pin goes high on the 74C922, [Data Available], while a key is pressed, use this to interrupt the PIC program.

If you 'OR' the 'A B C D' line input pattern with 30hex, it will give you ASCII '0', '1'... '9', :,:,<,=,>,?

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/