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
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.