UART Question & Answers July 26, 2021 By WatElectronics This article lists 100 UART MCQs for engineering students. All the UART Questions & Answers given below includes solution and link wherever possible to the relevant topic. A UART stands for Universal Asynchronous Receiver Transmitter. As the name suggests, it is an asynchronous type of communication protocol. When two devices need to communicate with each other, there need to be at least two connections between them, one is a transmission line and another one is a reception line for each device. A UART uses two wires between transmitter and receiver, and the UART frame consists of data, start/stop, and parity bits. The control, status, transmit, and receive registers are the UART registers. The control register contains settings for the UART, and the status register contains information about the UART state or condition. The Transmit Data Register Empty is a type of UART flag and the Serial Communication Status Register is a type of UART register. The UART is a widely used method, it uses only two wires, whereas the clock signal is not necessary. The disadvantages of a UART are it doesn’t support multiple slaves, and the data frame size is limited to a 9 bits max. In UART the data is transmitted in the form of bytes, its maximum speed is 115.2Kbps, and its data rate is 20Kbps. The transmitter section of a UART consists of a transmitter shift register and transmitter hold register. The Bluetooth modules, GPS units, microcontrollers, etc are the applications of a UART. 1). How many wires does UART use? One Two Three Four None Hint 2). The UART frame consists of ___________ bits Data Start/stop Parity All of the above None Hint 3). Which bit is used for error detection? Data Start/stop Parity All of the above None Hint 4). In which parity the number of 1’s must be even? Even Odd Both a and b None of the above None Hint 5). ____________ are the UART registers Control and status Receive Transmit All of the above None Hint 6). Which one of the following registers contains settings for the UART? Control Receive Transmit All of the above None Hint 7). Which one of the following registers contains information about the UART state or condition? Control Receive Transmit Status None Hint 8). The universal asynchronous receiver transmitter can be _____________ Simplex Full-duplex Half-duplex All of the above None Hint 9). In which parity the number of 1’s must be odd? Even Odd Both a and b None of the above None Hint 10). The number of bits sent every second is known as ________ rate Bit Byte Baud None of the above None Hint 11). The number of symbols sent every second is known as ________ rate Bit Byte Baud None of the above None Hint 12). Which one is a type of UART flag? TDRE RSR RDR None of the above None Hint 13). Which one is a type of UART register? TDRE RSR SCSR None of the above None Hint 14). What is the standard form of TDRE? Transmit Data Register Empty Transmit Data Rate Empty Transmit Data Register Enable None of the above None Hint 15). ____________ is an example for data communication equipment Modem Computer Terminal None of the above None Hint 16). What is the standard form of DTE? Data Transfer Equipment Data Terminal Equipment Data Transmit Equipment None of the above None Hint 17). What is the standard form of RDRF? Receiver Data Register Full Receiver Data Rate Full Register Data Receiver Full None of the above None Hint 18). ____________ is an example for data terminal equipment Terminal Computer Both a and b None of the above None Hint 19). What is the standard form of DCE? Data Communication Equipment Data Common Equipment Data Control Unit Equipment None of the above None Hint 20). What are the advantages of UART? Uses only two wires Widely used method Clock signal is not necessary All of the above None Hint 21). What is the standard form of RDR? Receiver Data Register Register Data Receiver Receiver Shift Register None of the above None Hint 22). What are the disadvantages of UART? Doesn’t support multiple slave Data frame size is limited to a 9 bits max Both a and b None of the above None Hint 23). What is the function of the UARTn_TXD signal? Serial data transmit-receive Clear to send handshaking signal Both a and b None of the above None Hint 24). The transmitter section of an UART consists of __________ Transmitter shift register Transmitter hold register Both a and b None of the above None Hint 25). What is the standard form of RSR? Receiver Data Register Register Shift Receiver Receive Shift Register None of the above None Hint UART MCQ's with Answers 26). What is the function of UARTn_RTX? Serial data receive Clear to send handshaking signal Both a and b None of the above None Hint 27). Which one of the following was used to enable or disable the interrupt request? IER IIR Both a and b None of the above None Hint 28). Which one of the following is a write-only register? FIFO control register Interrupt identification register Both a and b None of the above None Hint 29). What is the standard form of TDR? Transport Data Register Transmit Data Register Transmit Data Receiver None of the above None Hint 30). Which one of the following is a divisor latch? DLH DLL Both a and b None of the above None Hint 31). The baud rate of 8-bit UART is ___________ 1200bps 1500bps 9600bps None of the above None Hint 32). In 8-bit UART 1 byte is equal to ____________ bits Two Four Eight Sixteen None Hint 33). The bits transferred per second is _______ in 8-bit UART 1,000 5,098 8,192 6,789 None Hint 34). The data in a UART is detected by __________ Counter Clock Both a and b None of the above None Hint Read more about UART 35). What is the standard form of TSR? Transmit Shift Register Transport Status Register Transmit Status Receiver None of the above None Hint 36). The baud rate of 16 bit UART is ___________ 1200bps 1500bps 9600bps None of the above None Hint 37). In 16-bit UART 1 byte is equal to ____________ bits Two Four Eight Sixteen None Hint 38). The bits transferred per second is ______ in 16 bit UART 12,898 15,089 96,230 16,384 None Hint 39). Which register does UART contain? Clock Shift Both a and b None of the above None Hint 40). What is the standard form of SCCR? Serial Communication Control Register Serial Communication Common Register Serial Communication Register None of the above None Hint 41). _________ are the handshaking signals RI, DCD, CTS DSR, RTS DTR All of the above None Hint 42).The MSP430 family operates in _________ mode Synchronous Asynchronous Both a and b None of the above None Hint 43). What is the standard form of SCSR? Serial Communication Serial Register Serial Communication Status Register Serial Communication Register None of the above None Hint 44). The speed of the UART is ________ compare to USART Less High Very high None of the above None Hint 45). Which one of the following uses data signal for its functioning? UART USART Both a and b None of the above None Hint 46). In which one of the following the data is transmitted in the form of bytes? UART USART Both a and b None of the above None Hint 47). What is the standard form of UDR? UART Data Register USART Data Register USART Control Register None of the above None Hint 48). Which one of the following is an SPI register? SPDR SPCR SPSR All of the above None Hint 49). The transmitter type of LIN is ____________ Synchronous Asynchronous Both a and b None of the above None Hint 50). The data rate of a UART is __________ 10Kbps 20Kbps 40Kbps 50Kbps None Hint UART Interview Questions and Answers 51). The data rate of an SPI is __________ 10Mbps 25Mbps 40Mbps 50Kbps None Hint 52). Which one of the following scalability is low? UART SPI I2C None of the above None Hint 53). What is the standard form of USR? UART Serial Register UART Status Register USART Simple Register None of the above None Hint 54). The transmitter type of SPI is __________ Synchronous Asynchronous Both a and b None of the above None Hint 55). The data rate of I2C is ___________ 1Mbps 2Mbps 3Mbps 4Mbps None Hint 56). Which one of the following scalability is high? I2C UART SPI None of the above None Hint 57). What is the standard form of UBRR? UART Baud Rate Register USART Baud Rate Register USART Baud Register None of the above None Hint 58). The maximum speed of a UART is ___________ 115Kbps 1Kbps 115.2Kbps 1.2Kbps None Hint 59). The maximum speed of an SPI is ___________ 115Kbps 4Mbps 115.2Kbps 1.2Kbps None Hint 60). What is the standard form of UCR? UART Control Register USART Common Register USART Control Register None of the above None Hint 61). The transmitter type of I2C is _______ Synchronous Asynchronous Both a and b None of the above None Hint 62). The maximum speed of I2C is ___________ 15Kbps 4Mbps 115.2Kbps 1Mbps None Hint 63). The maximum distance of a UART is ___________ 10m 12m 15m 29m None Hint 64). In a UART, the maximum possible number of devices in a bus is ___________ Two Unlimited Four Eight None Hint 65). The associated protocol for serial interface RS-422 is ___________ UART I2C SPI None of the above None Hint 66). The master unit is ______ in UART Variable Fixed Variable or fixed None of the above None Hint 67). The maximum speed of RS-485 is ________ 15Kbps 4Mbps 115.2Kbps 1Mbps None Hint 68). The maximum distance of SPI is ___________ 0.1m 12m 15m 29m None Hint 69). In SPI, the maximum possible number of devices in a bus is ___________ Unlimited Two Eight Several None Hint 70). The master unit is ______ in USB 2.0 Variable Fixed Variable or fixed None of the above None Hint 71). The speed of USB is ______ 12M bit /sec 1M bit/sec 2M bytes/sec 4M bytes/sec None Hint 72). The speed of SCSI is ______ 160M bytes/sec 1M bytes/sec 2M bytes/sec 4M bytes/sec None Hint 73). The maximum distance of I2C is ____________ 1m 2m 0.5m 12m None Hint 74). In I2C, the maximum possible number of devices in a bus is _________ 6 4 16 127 None Hint 75). The maximum throughput of RS 232 is _____________ 20KB/sec 2KB/sec 28.8KB/sec 10KB/sec None Hint 76). The product availability of RS-232 is _____________ >500 <1000 >10,000 None of the above None Hint 77). The maximum distance of RS-485 is _________ 1.2km 15km 9km 10km None Hint 78). The maximum throughput of an Ethernet is _____________ 20KB/sec 125MB/sec 28.8KB/sec 10KB/sec None Hint 79). The maximum cable length of RS-232 is ___________ 1.2km 1.5km 9km 10km None Hint 80). The maximum cable length of USB is ______ 1.2km 1.5km 9km 30km None Hint UART MCQ's for Exams 81). What is the standard form of PCON? Power Control Power Control Receiver Power Control Register None of the above None Hint 82). How many lines does I2C use between multiple slaves and multiple masters? One Two Three Four None Hint 83). What is the standard form of UARTFR? UART Flag Register USART Flag Register UART Register None of the above None Hint 84). Which one of the following is a write-only register? FCR IIR Both a and b None of the above None Hint 85). The UART transmitter consists of ___________ FIFO module Shift register Hold register All of the above None Hint Read more about Shift Registers 86). An UART used for _______ access Mainframe Internet Both a and b None of the above None Hint 87). What is the standard form of MCR? Modem Control Register Modem Control Receiver Modem Common Register None of the above None Hint 88). __________ are the revision identification registers REVID1 REVID2 Both a and b None of the above None Hint 89). What is the standard form of MDR? Modem Definition Register Mode Definition Receiver Module Data Register None of the above None Hint 90). Which register contains the data to be transmitted? RBR THR FCR None of the above None Hint 91). Which register contains the data which is recently received? RBR THR FCR None of the above None Hint 92). Which register controls the universal asynchronous receiver transmitter frame formatting? RBR THR FCR LCR None Hint 93). What is the standard form of MSR? Modem Status Register Mode Simple Receiver Module Data Register None of the above None Hint 94). Which register is used to disable/enable the transmission? TER THR FCR LCR None Hint 95). Which one of the following registers is a least significant byte of a universal asynchronous receiver transmitter baud rate generator value? DLL DLM Both a and b None of the above None Hint 96). Which one of the following registers is a most significant byte of a universal asynchronous receiver transmitter baud rate generator value? DLL DLM Both a and b None of the above None Hint 97). What is the standard form of UDRE? UART Data Register Empty UART Data Register USART Data Register Empty None of the above None Hint 98). What are the applications of a UART? Bluetooth modules GPS units Microcontrollers All of the above None Hint 99). What is the standard form of DUDRE? Dual UART Data Register Empty Digital UART Data Register Empty Data UART Data Register Empty None of the above None Hint 100).The UART 16550A has ____________FIFO buffers 2-byte 4-byte 8-byte 16-byte None Hint Time's up
