[PIC] keypad with pic 16f877

[MARWEN007]

hi I have a keyboard as I can see below seek to program the buttons with microcontrollers 16f877 the problem that I had two common on the keyboard (pin5 and pin6) I do not know how I will do to make the two buttons (b1 and b2) are a different action (b3 and b4) as progarmme with mikroC I am looking for a simpler method to all the buttons soyont readable by the 16f877 example boutton each lED is light a

 

[AdityaRajNayak]

Hi,

It seems difficult to handle the 4 switches i.e B1, B2, B3, B4 (assuming the image shows push button switches) through 2 pins of the PIC.

However this problem can be resolved can be attemepted by following 2 ways:

Approach 1:
Either use on off switch instead of push button switch, in that case based upon binary combinations possible for 6 pins i.e 2^6 combinations would be possible using on/off status of each push button switch.

like

Pin 1(B1 on/off)	Pin 2(B1 on/off)	Pin 3(B1 on/off)	Pin 4(B1 on/off)	Pin 5(B1 on/off)	Pin 6(B1 on/off)	Pattern
on	off	off	off	off	off	1
off	on	off	off	off	off	2
off	off	on	off	off	off	3

Based upon the binary code, the action can be taken in code logic.

Approach 2:
Through ADC channels.
The on off switches can be arranged with a mesh resistors.
Based upon the switch on off conditions new resistirs shall be introduced into the circuit their by reduding/ increasing the effective analog voltage available at ADC channel.
A simple example has been suggested below:



Hope this is helpful..:smile: