Question

To identify that which key is being pressed, we need to:

(a) ground all the pins of the port at a time

(b) ground pins of the port one at a time

(c) connect all the pins of the port to the main supply at a time

(d) none of the mentioned

I got this question during an online interview.

Question is from Keyboard Interfacing in division 8051 Microcontroller of Microcontroller

Answer 1

Right option is (b) ground pins of the port one at a time

The explanation is: To detect that which key is being pressed, we need to ground the pins one by one.