4 Button Keypad

[Zegsy]

Hi All,

How can I implement a 4 button keypad for PIC16f627 to simulate Nigel Goodwin tutorial on 4x4 hex keypad.
Am trying my hands on the tutorial with a PIC kit I've got and it has just 4 buttons for input.

Thanks.

 

[Nigel Goodwin]

Hi All,

How can I implement a 4 button keypad for PIC16f627 to simulate Nigel Goodwin tutorial on 4x4 hex keypad.
Am trying my hands on the tutorial with a PIC kit I've got and it has just 4 buttons for input.

You don't, there's no need to multiplex four buttons, see tutorial two instead.

 

[parts-man73]

You could also connect all 4 switches to 1 ADC input - with resistors pulling each high. Each pull up resistor would have a different value, say 2k, 4k, 8k, 16K.

So when a switch is activated, it would know, not only that a switch is pressed, but it could tell which switch, by the ADC value. This could also tell if multiple switches are pressed simultaneously.

If you have 4 I/O pins available, Nigel's method would be easier to code.

Brian

 

[blueroomelectronics]

The 16f627 has no A/D.

 

[parts-man73]

Opps.... I didn't notice the target processor.