Q3. A keypad with 20 keys (arranged in 5 rows x 4 columns) is to be interfaced to an 8051 micro-controller. - Draw the diagram showing the interface using P1 (LSB) for columns and P2 (LSB) for rows. - Write necessary assembly language routines to: - De bounce the key pressed and key released - Identify the pressed key and find the code with C=1