4x4keypad code of pic16f877 in C language needed

[osha]

it is important

hi
i want 4x4keypad code of pic16f877 without using encoder in interface
please with c languge i ask about it more time in forum there is no any on give me perfect answer .
any way thanks for any help

 

[kalyanram]

Re: it is important

Hi Osha,
Don't worry here is the solution to your problem.
1) Firstly take a voltmeter and determine the coded sequence of the keyborad you have for each key now you know the hex code for each key. Now save these values in a lookup table.
2) Now for each key test the values with the mask set against a port where you ahve interface the keyborad with say 30ms dealy for debounce.
3) if this values is still available at the port accept it or reject it.

There is another way to this that will eliminate the sofware loops and dealys for you that would be by building a "chatter-free ciruit" at keyboard interface. For this you need a latch which detects the level transition in voltage when a key is pressed for you you just have to read the value straight from the port.

~Kalyan.

 

[thuvu]

Re: it is important

How about this

 

[osha]

Re: it is important

i think this solution(measure coded value if i have encoder) or what?


and ican't understand 2nd solution ,how?

for 2nd answer this code for avr iwant code for pic 16f877

please more detail,thanks.

 

[thuvu]

Re: it is important

I can only give you info about AVR. But if you Google I think you can find a lot of info.