Analog KeyPad

[kalpakchiev]

One pin analog keypad.

Any comments or proposals are welcomed.

Proteus design included

Best regards

[ipek]

dear kalpakchiev
not find 4bit bcd or binary output port 
best reagards..

[yahoo]

This solution is good but you have to keep in mind that you cannot use it for 2 or more simultaneously pressed keys and in battery operated units with floating power supply.

[kalpakchiev]

This solution is good but you have to keep in mind that you cannot use it for 2 or more simultaneously pressed keys and in battery operated units with floating power supply.

Your note is very appropriate. 2 or more simultaneously pressed keys can not be recognized. For battery operation can be added a routine like this:

if sample > 900 and sample < 1015 then
        LCDOUT $FE, $80,"   Low battery  "
        KeyPressed=255
endif

dear kalpakchiev
not find 4bit bcd or binary output port 
best reagards..

Having KeyPressed value it is easy to add an lookup table and set 4 I/O to corresponding BCD code.
 
Best regards

[jenniferkim]

I like it. It looks pretty good but let me remind you, it can't be used at the same time for more than one keys . you have to consider the battery operated units with floating power supply.