IOT Multiple Choice Questions on “USART Protocol”.
1. What is the protocol used by USART?
a) RS232
b) RS232C
c) RS485
d) RS422
Answer: b
Clarification: RS232C is a long established standard (“c” is the current version) that describes the physical interface and protocol for relatively low speed serial data communication between computers and relates devices.
2. USART provides a synchronous mode that is not in UART?
a) True
b) False
Answer: a
Clarification: Unlike a UART, USART offers the option of synchronous mode. In the program to program communication, the synchronous mode requires that each end of an exchange respond in turn without initiating a new communication.
3. Which of the following needs a clock?
a) Only Asynchronous
b) Only synchronous
c) Both synchronous and Asynchronous
d) Sometimes Synchronous
Answer: b
Clarification: Synchronous mode requires both data and clock. Asynchronous mode requires only data.
4. During receiving operation what does URXD have?
a) Positive edge
b) Negative edge
c) Level edge
d) Either raising or falling edge
Answer: a
Clarification: The receive operation is initiated by the receipt of a valid start bit. It consists of a negative edge at URXD, followed by the taking of majority vote from three samples, where 2 of the samples must be zero.
5. What is the timing of X?
a) 1/32 to 1/64 times of BRCKL
b) 1/42 to 1/63 times of BRCKL
c) 1/32 to 1/63 times of BRCKL
d) 1/32 to 1/56 times of BRCKL
Answer: c
Clarification: The timing of x is 1/32 to 1/63 of BRCLK, but at least BRCLK, depending on the division on the division rate of the baud rate generation.
6. The secondary implementation uses a fixed second clock divided which is divided by ______________
a) 4
b) 8
c) 32
d) 16
Answer: d
Clarification: The standard implementation uses a prescalar from any clock source and a fixed second clock divider which is usually a divided by 16.
7. The USART module supports ________ multiprocessor communication modes when the asynchronous mode is used.
a) one
b) two
c) three
d) five
Answer: b
Clarification: These formats can be used to transfer information between many microcomputers on the same serial link. Information is transferred as a block of frames from a particular source to one or more destinations.
8. How many asynchronous multiprocessor protocols are present?
a) 4
b) 3
c) 2
d) 5
Answer: c
Clarification: Both asynchronous multiprocessor protocols, the idel line and the address bit microprocessor mode allow efficient data transfer between multiple communication systems.
9. Which bit in control register defines the address bit or idle line multiprocessor protocol mode?
a) MM
b) URXWIE
c) URXIE
d) RXWake
Answer: a
Clarification: The MM bit in control register defines the address bit or idle line multiprocessor protocol mode. Both formats use the wake up on transmitting, using the address feature function (TWWake bit), and on activating the RXWake bit.
10. In idle line multiprocessor mode, a precise idle period can be generated to create efficient address character identifiers.
a) True
b) False
Answer: a
Clarification: In idle line multiprocessor mode, a precise idle period can be generated to create efficient address character identifiers.
11. In synchronous operation characters must be provided on time if not ______ error occurs.
a) Overrun error
b) Underrun error
c) Framing error
d) Parity error
Answer: b
Clarification: USART in synchronous operation characters must be provided on time until a frame is complete, if the controlling processor does not do so, this is an underrun error, and transmission of the frame is aborted.
12. HDLC stands for ___________
a) High level Data Link Control
b) High level Data Level Control
c) High level Data Link Coordinator
d) High level Data Link Commutator
Answer: a
Clarification: ISO standard high level data link control synchronous link layer protocols, which were with synchronous voice frequency modems.
13. SDLC stands for ___________
a) Synchronous Data Link Control
b) Synchronous Data Level Control
c) Synchronous Data Level Coordinator
d) Synchronous Data Link Coordinator
Answer: a
Clarification: Synchronous Data Link Control synchronous link layer protocols, which were with synchronous voice frequency modems. These protocols were designed to make the best use of bandwidth when modems were analog devices.
14. STR stands for___________
a) Synchronous Transmit Rate
b) Synchronous Target Rate
c) Synchronous Target Receive
d) Synchronous Transmit Receive
Answer: d
Clarification: Synchronous Transmit Receive, which were with synchronous voice frequency modems. These protocols were designed to make the best use of bandwidth when modems were analog devices.
15. BSC stands for ____________
a) Binary Service Communication
b) Bandwidth Synchronous Communication
c) Binary Synchronous Communication
d) Bandwidth Service Communication
Answer: c
Clarification: Binary Synchronous Communication, which were with synchronous voice frequency modems. These protocols were designed to make the best use of bandwidth when modems were analog devices.