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WorksheetsMPMC MCQ 8051 APPS
Total questions: 30
Worksheet time: 30mins
In the attached circuit, K1 and K8 are closed where K1 is LSB. Other keys are open. The input value read in Port 1 is
FFH
18H
81H
00H
In the attached circuit, all keys are open. The input value read in Port 1 is
FFH
18H
81H
00H
In the attached program, the microcontroller,
Waits for a key to be pressed
Waits for a key to be released
Clears the accumulator
Waits for a delay to be over
Consider the following statements:
1) LCALL can call a subroutine anywhere within the 2K memory page.
2) ACALL can call a subroutine within 128 bytes memory space.
Both statements are true.
Both statements are false
First statement is true, second statement is false
First statement is false, second statement is true.
Consider the following statements: The advantage in
organising keys of a keyboard in matrix form are,
1) It reduces the number of port pins required.
2) Only input pins will be required.
Both statements are true.
Both statements are false
First statement is true, second statement is false
First statement is false, second statement is true.
DPTR=3000H; A = 05H; What is the content of the accumulator after execution of the instruction
MOVC , @A+DPTR
30H
05H
00H
May not be any of the above
DPTR=3000H; A = 05H; PC=2000H; What is the content of the accumulator after execution of the instruction
MOVC , @A+PC
30H
05H
20H
May not be any of the above
In the attached circuit for a matrix keyboard interfaced with 8051, P1=F0H; If Key1 is pressed, the content of P2 is
FFH;
0CH;
FCH
00H;
In the attached circuit for a matrix keyboard interfaced with 8051, P1=00H; If Key 7 is pressed, the content of P2 is
FFH;
0CH;
F7H
00H;
In the attached circuit for a matrix keyboard interfaced with 8051, the lookup table contains
the decimal numbers 00 to 15
the hexadecimal numbers 0 to F
the ascii code of the numbers 0 to F
None of the above
In keyboard routine, debouncing is done since
Key values take time to stabilise
to match processor time with keypress time
to reduce memory requirement
None of the above
In the attached LED driver, what is the BCD input?
0000
0001
1111
None of the above
In the attached LED driver, to display 9 in the LED, what is the input?
0001
1001
1111
0000
In the attached, stepper motor driver, what is the purpose of the resistance?
Reduce time constant L/R
Increase stepping rate
Get more torque
All of the other options
In the 8051 based washing machine control, which of these is not an input?
Level sensor
Stepper motor supply
Wash program select
Load select
In the 8051 based washing machine control, which of these is not an output?
Machine ON indication
Stepper motor supply
Water inlet valve control
Load select
In the 8051 based washing machine control, which of these operations requires the operation of stepper motors?
Soak
Spin
Agitate
Fill
Load cell operation is based on
Thermo couple effect
Piezo resistive effect
Miller effect
None of the above
In washing machine control, during washing,
Only agitator rotates
Only wash basket rotates
Agitator and Wash basket rotate in opposite directions
Agitator and Wash basket rotate in same direction
Which of the following cannot be used for position sensing in a servo motor?
Potentiometer
Thumbwheel switch
Encoder
Resolver
Which of the following motors can be used for precise position control?
Induction motor
Synchronous motor
DC motor
Servo motor
8255 has how many ports?
1
2
3
4
In 8255, Port B cannot operate in which of the following modes?
Mode 0
Mode 1
Mode 2
All of the above
Which of these is not a handshaking signal in 8255?
IBF
OBF
ACK
RD
IN 8255, bits of which port can be manipulated through the control register?
Port A
Port B
Port C
None of the above
In 8255, which register is selected when A0=1, A1=1 and chip is selected?
Port A
Port B
Port C
Control register
In 8255, PC7 has to be made 1. The value to be written in to the control register is
18
10
FF
0F
IN 8255, Group A comprises
Port A and Port C lower
Port A and Port C upper
Port A and Port B
Port B and Port C lower
8255 has
28 pins
40 pins
64 pins
None of the above
IN 8255, Group B comprises
Port A and Port C lower
Port A and Port C upper
Port A and Port B
Port B and Port C lower
