IOT Multiple Choice Questions on “UART Protocol”.
1. GPS module like SIM900/800 uses which protocol?
a) UART protocol
b) USART protocol
c) SPI protocol
d) I2C protocol
Answer: a
Clarification: GSM/GPS modules like SIM900/800 uses UART communication for accepting AT commands that are used to control them and gather the replies.
2. Finger print sensor uses which interface?
a) USART protocol
b) UART protocol
c) SPI protocol
d) I2C protocol
Answer: b
Clarification: Projects that use RFID modules can be built with modules that have a UART interface. This even applies to some finger print sensors.
3. RS232 is used for long range wired communication.
a) True
b) False
Answer: a
Clarification: For long range communications we can convert UART protocol using an external IC to RS232 or RS485, the latter of which can be used for wired communication @100 kbits/sec up to 1.2km.
4. UART is similar to _________
a) SPI protocol
b) I2C protocol
c) HTTP protocol
d) MQTT protocol
Answer: b
Clarification: UART(Universal Asynchronous Receiver/Transmitter) is a small, efficient communication device, similar to I2C.
5. What does UART contain?
a) Parallel register
b) Shift register
c) Clock
d) Parallel shift register
Answer: b
Clarification: UART contains a shift register, which is the fundamental method of conversion between serial and parallel forms.
6. Communication in UART is ___________
a) Only simple
b) Only duplex
c) Only full duplex
d) Simplex, half duplex, full duplex
Answer: d
Clarification: Communication may be simplex(in one direction only no provision for the receiving device to send data back to the transmission device), full duplex(both devices send and receive data at the same time), half duplex(devices takes turns transmitting and receiving).
7. Start bit of UART is logic high.
a) True
b) False
Answer: b
Clarification: The start bit is logical low. The start bit signals the receiver that a new character is coming.
8. Which error occurs when the receiver can’t process the character?
a) Overrun error
b) Underrun error
c) Framing error
d) Break condition
Answer: a
Clarification: An over run error occur when the receiver cannot process the character that just came in before the next one arrives. If the CPU or DMA controller does not service the UART quickly enough and the buffer become full, an over run will occur, and incoming will be lost.
9. What is WD1402A?
a) SPI
b) USART
c) SPIUART
d) I2C
Answer: c
Clarification: WD1402A is the first single chip UART on general sale. Introduced about 1971. Compatible chip included the Fairchild TR1402A and the general instruments AY-5-1013.
10. What is the speed of the 8250 UART?
a) 4800bits/sec
b) 1200bits/sec
c) 12000bit/sec
d) 9600bits/sec
Answer: d
Clarification: The 8250 UART has one character buffer for the receiver and the transmitter each, which meant that communications software performed poorly at speed above 9600bits/sec, especially it operating under a multitasking system or if handling interrupts from disk controllers.
11. Which error occurs when UART transmitter has completed sending a character and the transmit buffer is empty?
a) Overrun error
b) Underrun error
c) Framing error
d) Break condition
Answer: b
Clarification: An Under run error occurs when UART transmitter has completed sending a character and the transmit buffer is empty. In asynchronous mode this is treated as an indication that no data remains to be transmitted.
12. Which error occurs when the designated start and stop bits are not found?
a) Overrun error
b) Underrun error
c) Framing error
d) Break condition
Answer: c
Clarification: A framing error occurs when the designated start and stop bits are not found. If the data line is not in the expected state when the stop bit is expected, a framing error will occur.
13. Which error occurs when the parity of the number of 1 bit disagrees with that specified by the parity bit?
a) Overrun error
b) Underrun error
c) Framing error
d) Parity error
Answer: d
Clarification: A parity error occurs when the parity of the number of 1 bit disagrees with that specified by the parity bit. Using parity is optional, so this error will only occur if parity checking has been enabled.
14. A __________ occurs when the receiver input is at the space level.
a) Overrun error
b) Underrun error
c) Framing error
d) Break condition
Answer: d
Clarification: A break condition occurs when the receiver input is at the space level for longer than some duration of time, typically, for more than a character time.
15. The term break derives from ___________ signaling.
a) Current loop
b) Voltage loop
c) Power loop
d) Current and Power loop
Answer: a
Clarification: The term break derives from current loop signaling, which was the traditional signaling used for teletypewriters.