How many pins needed to generate I/O ports in 8051?
30
34
32
28
Find the contents of control word of the 8255 for the following configuration: All the ports of A, B and C are input ports (mode 1)
3FH
BFH
9FH
1FH
In 8255, bit addressability is a available with port
A
B
C
D
Why interface chips are necessary in a microcontroller based system?
To solve the speed problem
To synchronize the data transfer between the CPU and I/O device
To synchronize the data transfer between the CPU and the I/O device, as well as to resolve the speed problem
None of the mentioned
Which of the following can be associated with bouncing contacts?
Push button switches
Toggle Switches
Both push-button switches and toggle switches
Neither push-button switches not toggle switches
The term DIP in the phrase ‘DIP switch’ stands for
Double In-lane Package
Double In-line Package
Dual In-line Package
Dual In-lane Package
Find the control word of the 8255 for resetting BIT 4 of Port C
00001111
10001111
10001000
00001000
To get 2 displayed by a 7 segment display (common mode), what should be the combination of 8051 pins (P1.7 – P1.0)?
01111101
10111110
01011011
10100100
Which of the following is the correct combination to select port C in an 8255 chip?
CS = 0, A1 = 0, A0 = 0
CS = 0, A1 = 0, A0 = 1
CS = 0, A1 = 1, A0 =0
CS = 1. A1 = 0, A0 = 0
What is the function of watchdog timer?
The watchdog Timers is an external timer that resets the system if the system if the software fails to operate properly.
The watchdog Timers is an internal timer that sets the system if the system if the software fails to operate properly.
The watchdog Timers is an internal timer that resets the system if the system if the software fails to operate properly.
None of the mentioned
In 8051, timer 1 run can be controlled by
TR1
TF1
IE1
IT1
The delay produced by 8051 mode 1 timer with TH = FF and TL = 00, crystal frequency 11.0592MHz is
277.00 microsecond
277.76 microsecond
278.00 microsecond
278.76 microsecond
8051 counters in mode 2 are
8 bit
16 bit
12 bit
Size Programmable
Which register in an 8051 microcontroller contains the SMOD bit?
SBUF
TMOD
PCON
TCON
In 8051, the instruction “MOV IP, #00000101” sets priorities of interrupts as
RI + TI > TF1 > INT0 > TF0 > INT1
TF1 > RI + TI >INT0 > TF0 > INT1
INT0 > INT1 > TF0 > TF1 > RI + TI
INT1 > INT0 > TF1 > TF0 > RI + TI
In Timer counter register of 8051, Mode 1 uses
8-bit timer
16-bit timer
13-bit timer
32-bit timer
What is the default interrupt priority in 8051?
INT0 > TF0 > RI+TI >INT1 > TF1
INT0 > TF1 > RI+TI > INT0 > TF0
INT0 > TF0 > INT1 > TF1 > RI + TI
INT1 > TF1 > INT0 > TF0 > RI + TI
Which bits in the PCON register of an 8051 microcontroller corresponds to the idle and power down modes?
PCON.0 – Idle mode, PCON.1 – Power down mode
PCON.1 – Idle mode, PCON.0 – Power down mode
PCON.0 – Idle mode/power down mode
PCON.1 – Idle mode/power down mode
In serial control (SCON) register, SCON.5 is used to
Transmit interrupt flag
Receive interrupt flag
Used for multi-processor communication
Receive enable
In idle mode of power control register, which of the following is not true?
All of registers, port and internal RAM maintain their data
The ALE and PSEN output are held low
The internal CPU clock is gated off
Interrupt, Timer and serial port functions act normally
8 input DAC has
8 Discrete voltage levels
64 Discrete voltage levels
128 Discrete voltage levels
256 Discrete voltage levels
Which port is called a dedicated I/O port and which one is called a multi-functional I/O port in 8051?
Port 1 and port 3
Port 0 and port 2
Port 2 and port 3
Port 3 and port 1
How many SFRs related to timer/counter operation?
3
4
5
6
Which one is a temperature sensor?
LM35
LM45
LM30
LM65
In 8051 microcontroller, Timer operating in mode 0, the timer register size is
8 bit
13bit
18bit
64bit
In 8051 microcontroller, show the bit that is used to start/stop the timer/counter?
Timer overflow
Timer Run
Interrupt run
Interrupt enable
In the TMOD register which bit is used to indicate timer 0/counter0 operation?
GATE
C/T’
M1
M0
How many interrupts in 8051?
4
6
5
7
In the IP register, is it possible to give priority to all interruptions at a time?
Yes
No
Which one of the following SFR is used for serial communication?
PCON
TMOD
SMOD
TCON
In the 8051 microcontrollers, What will be the timer clock frequency if the crystal frequency is 12 MHZ?
1MHZ
12MHZ
34MHZ
2MHZ
The timer1 operating in mode3 what will be the value loaded in the TMOD register?
20H
30H
34H
56H
To enable external interrupt 1which value to be loaded in the IE register?
04H
05H
06H
07H
In ADC interface with 8051 which hexa address is used to read ADC output?
C000H
D000H
E000H
F000H
For stepper motor interface which port of 8051 used for the forwarding operator?
Port 0
Port 1
Port 2
Port 3
SFRs location in internal RAM is
70H TO 80H
80H to FFH
00H to 80H
00H to 70H
EA’ pin of 8051 is connected to VCC , the memory split up of program memory is,
64Kb of internal ROM,0Kb of external memory
0Kb of internal ROM,64Kb of external memory
4Kb of internal ROM,60Kb of external memory
4Kb of internal ROM,64Kb of external memory
8051 Timers in Mode 1 configuration rolls over when it goes from _____.
FF to 00
1FF to 000
1FFF to 0000
FFFF to 0000
Which of the following interrupts in 8051 has the lowest priority?
External interrupt 0
Timer 1 interrupt
Serial port interrupts
External interrupt 1
The asynchronous transmission always begins with _____.
Start bit
Stop bit
Parity bit
Sync bit
The ADC0848 is an ______ bit converter.
4
8
12
16
A stepper motor with a step angle of 15 degrees has ____ steps per revolution.
72
27
24
16
LM 34 and LM35 are examples of ______ sensors.
Pressure
Moisture
Temperature
Rain Drop
When the instruction MOV TMOD, #20H is executed, __________ is selected.
Mode 0 of Timer 0
Mode 1 of Timer 1
Mode 0 of Timer 2
Mode 2 of Timer 1
The number of address lines and data lines required for the 256K´4 SRAM chip is __________.
8, 4
18, 4
8, 8
18, 8
Which of the following interface is used for waveform generation using the 8051 microcontrollers?
ADC
DAC
ACD
CAD
Interpret the name of the processor that has both RISC and CISC features?
PIC controller
Pentium processor
ARM processor
SHARC processor
Choose the use of TMOD register among the following in 8051 controllers,
Contains status information
Timer/counter control register
Timer/counter modes of operation
Idle bit, power down a bit
Select how the resolution of an ADC depends on
Number of bits and maximum voltage range
Number of bits and input voltage range
Number of bits and minimum voltage range
Maximum and minimum voltage range
Each port line of a port can individually source a current of up to
0.2 mA
0.25 mA
0.5 mA
0.75 mA
The open-drain bidirectional (input or output) port with internal pullups is
Port 0
Port 1
Port 2
Port 3
If the EA (active low) signal is grounded then the execution
Directly start from main memory
Directly start from a 16-bit address in the main memory
Directly start from a 16-bit address in program memory
Directly start from RAM
When the port lines of a port are to be used as input lines then the value that must be written to the port address is
F0H
0FH
FFH
00H
The configuration in which each LED receives an operating current of 8mA from the power supply while the port lines sink the current on each port line is.
Common Port Configuration
Common Anode Configuration
Common Cathode Configuration
None of the Mentioned
The number of LEDs that can be connected to a port of 8051, if all are expected to glow simultaneously is
6
8
10
12
Which is true in interfacing 7 segment code display?
Transmitted by the second port
The display is selected by the third port
The display is selected by the second port
None of the mentioned
The number of scans of the complete 8 digit display that can be carried out in one second is
15
25
35
55
To convert its current output into a voltage, the DAC 0808 is connected with
Transistor (BJT) Externally
FET Externally
OPAMP Externally
OPAMP Internally
How many rows and columns are present in a 16*2 alphanumeric LCD?
rows=2, columns=32
rows=16, columns=2
crows=16, columns=16
rows=2, columns=16
How many data lines are there in a 16*2 alphanumeric LCD?
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