This set of Embedded Systems Multiple Choice Questions & Answers (MCQs) focuses on “UART”.
1. What does UART stand for?
a) universal asynchronous receiver transmitter
b) unique asynchronous receiver transmitter
c) universal address receiver transmitter
d) unique address receiver transmitter
Explanation: The UART or universal asynchronous receiver transmitter is used for the data transmission at a predefined speed or baud rate.
2. How is data detected in a UART?
d) first bit
Explanation: The data can be detected by the local clock reference which is generated from the baud rate generator.
3. Which of the signal is set to one, if no data is transmitted?
Explanation: The TXD signal goes to logic one when no data is transmitted. When data transmit, it sets to logic zero.
4. What rate can define the timing in the UART?
a) bit rate
b) baud rate
c) speed rate
d) voltage rate
Explanation: The timing is defined by the baud rate in which both the transmitter and receiver are used. The baud rate is supplied by the counter or an external timer called baud rate generator which generates a clock signal.
5. How is the baud rate supplied?
a) baud rate voltage
b) external timer
d) internal timer
Explanation: The baud rate is supplied by the counter or an external timer called baud rate generator which generates a clock signal.
6. Which is the most commonly used UART?
Explanation: The Intel 8253, 8254 and 8259 are timers whereas Intel 8250 is a UART which is commonly used.
7. Which company developed 16450?
c) National semiconductor
Explanation: The Intel 8250 is replaced by the 16450 and 16550 which are developed by the National Semiconductors. 16450 is a chip which can combine all the PC’s input output devices into a single piece of silicon.
8. What does ADS indicate in 8250 UART?
a) address signal
b) address terminal signal
c) address strobe signal
d) address generating signal
Explanation: The ADS is address strobe signal and is working as active low in 8250 UART. The ADS signal is used to latch the address and chip select signals while processor access.
9. Which of the following signals are active low in the 8250 UART?
Explanation: The BAUDOUT signal is active low whereas DDIS, INTR and MR are active high in the 8250 UART. BAUDOUT is the clock signal from the transmitter part of the UART. DDIS signal goes low when the CPU is reading data from the UART. INTR is the interrupt pin. MR is the master reset pin.
10. Which of the signal can control bus arbitration logic in 8250?
Explanation: DDIS signal goes low when the CPU is reading data from the UART and it also controls the bus arbitration logic.
Sanfoundry Global Education & Learning Series – Embedded System.
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