How to interface key pad with less number of MCU Pins ?

[kapila]

Hi All ,

I am making some application using 8 pin microcontroller. I want to make some hardware to enter 4 digit number , which is goint to interface with
the microcontroller. I have not enough microcontroler pins , to connect 10 switches ( to feed digit 0 - to 9 ). Because for reduce the cost and space , I must use 8 pin MCU. Can any body tell me , is there any easy way to do this using 1 or 2 microcontroller pins ?

Thanks,
Kapila

[Magneto]

Hi Friend ,

You can easily do this by one MCU pin , if your MCU have some ADC pins. then you have to make some hardware using voltage deviding resistors ,
which apply unique voltage on a ADC pin . when pressing each of the numeric switches ( 0 to 9 ).

Then you have to decode the voltage values into nemeric key values ,in the Microcontroller program ?

Good Luck