This set of Microprocessor Multiple Choice Questions & Answers (MCQs) focuses on “Serial Communication Unit”.
1. The serial communication is
a) cheaper communication
b) requires less number of conductors
c) slow process of communication
d) all of the mentioned
View Answer
Explanation: The serial communication requires less number of conductors and thus it is cheaper. It is slow as the bits are transmitted one by one along with start, stop and parity bits.
2. The serial communication is used for
a) short distance communication
b) long distance communication
c) short and long distance communication
d) communication for a certain range of distance
View Answer
Explanation: Serial communication is more popular for communication over longer distances as it requires less number of conductors.
3. The mcs 51 architecture supports
a) serial transmission and reception
b) simultaneous transmission and reception
c) transmission and reception of data using serial communication interface
d) all of the mentioned
View Answer
Explanation: The mcs 51 architecture supports simultaneous transmission and reception of binary data byte by byte i.e. full duplex mode of communication. It supports serial transmission and reception of data using standard serial communication interface and baud rates.
4. The number of bits transmitted or received per second is defined as
a) transmission rate
b) reception rate
c) transceiver rate
d) baud rate
View Answer
Explanation: Here, baud rate can be defined as the number of bits transmitted or received per second.
5. The task of converting the byte into serial form and transmitting it bit by bit along with start, stop and parity bits is carried out by
a) reception unit
b) serial communication unit
c) transmission unit
d) all of the mentioned
View Answer
Explanation: the serial communication unit consists of transmission unit and reception unit. The task of converting the byte into serial form and transmitting it bit by bit along with start, stop and parity bits is carried out by transmission unit.
6. The transmission unit does not require assistance from processor if once a byte for transmission is written to
a) SCON register
b) SBUF register
c) SFR address
d) Any of the mentioned
View Answer
Explanation: once a byte for transmission is written to the serial buffer(SBUF) register, the transmission unit does not require assistance from a processor.
7. The common unit shared by the receiver unit and transmission unit of serial communication unit is
a) SCON(Serial Port Control) Register
b) SBUF(Serial Buffer) register
c) 8-bit serial data interface
d) All of the mentioned
View Answer
Explanation: The transmission unit and receiver unit both are controlled by using a common SCON(Serial Port Control) Register. Also both units share a common serial buffer(SBUF) register which is a common 8-bit serial data interface.
8. During serial reception, the buffer that receives serial bits and converts to a byte is
a) receive buffer 0
b) receive buffer 1
c) receive buffer 2
d) none
View Answer
Explanation: During serial reception, the receive buffer 1 receives serial bits and converts to a byte, it then transfers the received parallel byte in receive buffer 2.
9. If SM0=1, SM1=0, then the transceiver selected is
a) 8-bit synchronous
b) 9-bit synchronous
c) 8-bit asynchronous
d) 9-bit asynchronous
View Answer
Explanation: If SM0=1, SM1=0, then the 9-bit asynchronous transceiver is selected.
10. If the microcontroller is expected to communicate in a multiprocessor system, then the required condition is
a) SM0 is set
b) SM1 is set
c) SM2 is set
d) REN is set
View Answer
Explanation: The bit, SM2 is set if the microcontroller is expected to communicate in a multiprocessor system.
11. In mode 2, the baud rate depends only on
a) SMOD bit
b) SCON bit
c) Oscillator clock frequency
d) SMOD bit and oscillator clock frequency
View Answer
Explanation: In mode 2, the baud rate depends only on SMOD bit and oscillator clock frequency.
12. The mode that offers the most secured parity enabled data communication at lower baud rates is
a) mode 2
b) mode 1
c) mode 0
d) all of the mentioned
View Answer
Explanation: The mode 3 offers the most secured parity enabled data communication at lower baud rates of mode 1.
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