Digital Communications

Question 1

We need to provide slave address for UART communication protocol.

True
False

Answer 1

False

UART communication, there is no concept of a “slave address” as you would find in protocols like I2C or SPI. UART is a point-to-point communication protocol, and it typically involves only two devices: a transmitter and a receiver.

Question 2

Which one of the following can convert a lower-case alphabet to an upper-case alphabet (e.g. ‘a’ –> ‘A’)

lower_alphabet = upper_alphabet + 0x32;

lower_alphabet = upper_alphabet - 0x20;

upper_alphabet = lower_alphabet - 20;

upper_alphabet = lower_alphabet - 0x20;

Answer 2

upper_alphabet = lower_alphabet - 0x20;

Question 3

Which digital communication protocol is asynchronous?

I2C

UART

All of them.

SPI

Answer 3

UART
UART communication does not rely on a shared clock signal as synchronous protocols like I2C and SPI do. Instead, it uses start and stop bits to frame each data byte, making it asynchronous.

Each data byte is sent individually with its start and stop bits, and there is no need for both the transmitter and receiver to be synchronised to a common clock signal.

This asynchronicity provides flexibility in UART communication but requires both parties to agree on the data rate or baud rate to ensure proper communication

Question 4

How is data transmitted onto the serial console?

One byte at a time

One sentence at a time

One word at a time

One string at a time

Answer 4

One byte at a time

Question 5

Half-duplex transmission between unit A and unit B is where:

Unit A sends half of the data, then unit B sends the other half

Only Unit A can transmit, Unit B can only receive

Units A and B take turns to transmit

Units A and B transmit at the same time

Answer 5

Units A and B take turns to transmit

Question 6

A synchronous communications link has a separate clock wire:

True
False

Answer 6

True

In a synchronous communication link, there is typically a separate clock wire that carries the clock signal. This clock signal is used to synchronise the timing of data transmission between the sender (transmitter) and the receiver. Synchronous communication is characterised by a shared clock signal that ensures that both the sender and receiver are operating in harmony, allowing for precise timing and coordination of data transfer.

In contrast, asynchronous communication, such as in UART, does not rely on a shared clock signal but uses start and stop bits to frame data bytes, making it less dependent on precise synchronisation.

Question 7

Which one of the following can convert a upper-case alphabet to an lower-case alphabet (e.g. ‘A’ –> ‘a’)

lower_alphabet = upper_alphabet + 0x20;

lower_alphabet = upper_alphabet + 0x32;

upper_alphabet = lower_alphabet - 20;

upper_alphabet = lower_alphabet + 0x20;

Answer 7

lower_alphabet = upper_alphabet + 0x20;

Question 8

A 7-bit ascii data is transmitted with 1 start bit, 1 stop bit and 1 parity bit at a baud rate of 9600. How fast is the 7-bit ascii data being transmitted?

0.115 ms

1.042 ms

0.104 ms

1.146 ms

Answer 8

1.042 ms

7+1+1+1=10 bits.

T= 9600/10​ = 0.00104167 seconds

To convert this to milliseconds

T=0.00104167×1000=1.04167 milliseconds

Question 9

In EIA/RS-232, what indicates that a character is about to be transmitted

Transmit indicator wire

The chip select (CS) line

The header is transmitted first

A start bit

Answer 9

A start bit

Question 10

Which of the following statement is true?

An example of a asynchronous communication is Rendezvous and an synchronous communication is Message Queue.

An example of a synchronous communication is Rendezvous and an asynchronous communication is Message Queue.

Both Rendezvous and Message Queue are examples of asynchronous communication.

Both Rendezvous and Message Queue are examples of synchronous communication.

Answer 10

An example of a synchronous communication is Rendezvous and an asynchronous communication is Message Queue.

Question 11

A MSP432 receive “10001011” which consist of 7 data bits and 1 parity bit. If the message is received correctly, the transmission is configured as even parity.

True
False

Answer 11

True

Question 12

Using a single parity bit when transmitting a 7-bit character over EIA/RS-232, you can:

Indicate to the transmitter that it must re-send the character

Detect when 1 or 3 bits are received in error

Correct an error of 1 bit in the received character

Detect when 2 or 4 bits are received in error

Answer 12

Detect when 1 or 3 bits are received in error

Question 13

An SPI master can only have one slave

True
False

Answer 13

False

Question 14

The I2C protocol has separate wires for transmit and receive (called MOSI and MISO)

True
False

Answer 14

False

I2C is a two-wire communication protocol that enables multiple devices to communicate over the same bus using these two lines. The devices on the bus take turns transmitting and receiving data as needed, and there is no strict separation of transmit and receive lines as seen in protocols like SPI.