CET Embedded Systems & Programming 3 — Questions and Answers
Question 1: Which serial communication protocol uses separate MOSI, MISO, SCLK, and chip-select lines?
- I2C
- UART
- SPI (Correct answer)
- CAN
Correct answer: SPI
SPI (Serial Peripheral Interface) uses four dedicated lines: MOSI, MISO, SCLK, and one CS line per slave device.
Question 2: In I2C communication, what is the function of pull-up resistors on the SDA and SCL lines?
- They provide termination to prevent signal reflections
- They pull the open-drain lines high when no device is driving them low (Correct answer)
- They limit current into the slave device
- They filter high-frequency noise from the bus
Correct answer: They pull the open-drain lines high when no device is driving them low
I2C uses open-drain outputs, so pull-up resistors are required to return the bus to a logic-high idle state when no device is asserting it low.
Question 3: What does 'baud rate' specify in a UART configuration?
- The number of data bits per frame
- The number of symbol transitions per second on the line (Correct answer)
- The voltage swing of the signal
- The parity check interval
Correct answer: The number of symbol transitions per second on the line
Baud rate is the number of signaling events (symbols) per second; in UART with binary signaling, it equals the bit rate.
Question 4: In SPI, which device generates the clock signal (SCLK)?
- Any device that has data to send
- The slave device currently being addressed
- The master device exclusively (Correct answer)
- The device that last sent a start condition
Correct answer: The master device exclusively
In SPI, only the master generates the clock; slaves synchronize data transmission and reception to this clock.
Question 5: What is the maximum number of devices addressable on a standard I2C bus using 7-bit addressing?
- 64
- 128
- 112 (Correct answer)
- 256
Correct answer: 112
7-bit addressing provides 128 possible addresses, but 16 are reserved, leaving 112 usable addresses for slave devices.
Question 6: CAN bus is most commonly used in which application domain?
- Consumer audio equipment
- Automotive and industrial control networks (Correct answer)
- High-speed PC peripherals
- Wireless sensor networks
Correct answer: Automotive and industrial control networks
CAN (Controller Area Network) was designed for automotive ECU networks and is widely used in industrial automation due to its noise immunity and multi-master support.
Question 7: In UART framing, what is the purpose of the stop bit?
- To signal that a parity error has occurred
- To mark the beginning of a new data byte
- To signal the end of a data frame and allow receiver re-synchronization (Correct answer)
- To indicate that the transmitter is ready for the next byte
Correct answer: To signal the end of a data frame and allow receiver re-synchronization
The stop bit (logic HIGH) terminates each frame, giving the receiver time to process the byte before the next start bit (logic LOW) arrives.
CET Embedded Systems & Programming 3
Which serial communication protocol uses separate MOSI, MISO, SCLK, and chip-select lines?