Keyboard Interfacing with PIC 16F877 - MCQs with answers

Keyboard Interfacing with PIC 16F877 - MCQs with answers

1. What is the purpose of using Schmitt Trigger in the hardware circuit for key debouncing?

a. Noise Elimination
b. Improvement in Noise Immunity
c. Increase in Noise Figure
d. Reduction in Noise Temperature

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2.Which lines are driven low under the software control during interfacing HEX keyboard with PIC 16F877?

a. Scan Lines
b. Return Lines
c. Both a & b
d. None of the above

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3. Which keys are encoded for scan lines with '1101' value (RB1 low) condition ?

a. 0, 4, 8, C
b. 1, 5, 9 , D
c. 2, 6, A, E
d. 3, 7, B, F

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4. What value of 'B' should be loaded in the TRISB register if return lines (RB7 : RB4)and RB3:RB0 are supposed to be inputs and outputs respectively after the PORT B initialization?

a. 11000100
b. 11110011
c. 11110001
d. 11110000

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