Keyboard Interfacing MCQ’s

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This set of Microcontroller Multiple Choice Questions & Answers (MCQs) focuses on “Keyboard Interfacing”.

1. To see if any key is pressed, all rows are grounded.
a) true
b) false
c) can’t be said
d) depends on the conditions

2. Identify the row and the column for the following case when for the row D3-D0= 1110 and for the column D3-D0= 1101
a) first row and second column
b) first row and third column
c) second row and first column
d) second row and second column

3. In reading the columns of a keyboard matrix, when no key is pressed then all the pins show?
a) 0
b) 1
c) F
d) 7

4. What are the actual steps that are followed in identifying any key that is being pressed?
a) wait for the debounce time
b) identify the key that is pressed
c) initially no key should be pressed
d) all of the mentioned

5. The key detection and the key identification are two different procedures?
a) true
b) false
c) depends on the circumstances
d) difficult to tell

6. If the pins of the keyboard are used as an interrupt, then these pins will cause an interrupt of what type?
a) External hardware interrupt
b) Timer interrupt
c) TI/RI interrupt
d) None of the mentioned

7. To identify that the key is present in which row and the column
a) we ground the bits of the row one by one
b) we ground the bits of the column one by one
c) we connect the bits of the row to the logic level 1 one by one
d) we can connect the columns to the logic level 1 one by one

8. What is described by the following command?
KCODE0<<1
a) load KCODE0 with 0
b) rotate the contents of the KCODE0 register to the right
c) rotate the contents of the KCODE0 register to the left
d) none of the mentioned

9. What will happen if the two keys of the keyboard are pressed at a time?
a) both the keys will be displayed on the screen
b) the key which is being actually pressed(for more then 20microseconds) will be displayed
c) the key that is pressed first will be displayed
d) none of the mentioned

10. Why initially all keys are considered open before detecting the key pressed?
a) to make the task easy
b) to remove the errors caused by other pressing keys during detection
c) to remove the flow problems
d) none of the mentioned

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