ECE 331 Preparation Exercise 10 Solutions
Please refer to Module 9 course notes to answer the following questions.
1. Describe the difference between parallel and serial communications.
Parallel will transmit multiple bits of data at the same time but requires one signal/wire
per bit.
Serial will transmit only 1 bit of data at a time, placing data words/packets on a single line
in a time-sequence manner, and only requires a single data signal/wire.
2. Describe and contrast synchronous vs. asynchronous serial communications.
Synchronous uses a clock to regulate and indicate the timing of a serial bit sequence.
Asynchronous relies on preset timing protocol to determine the timing of a serial bit
sequence. It does not require a clock and thus can be implemented with fewer
signals/wires, but requires negotiation of timing protocol between receiver and
transmitter and can be more prone to errors than synchronous protocols.
3. Discuss the impact, or limitations, of choosing a serial communication standard with a shared receive
and transmit line.
A shared Rx/Tx line minimizes the number of signals/wires needed but eliminates the
opportunity to simultaneously transmit and receive.
4. What term defines the bit rate for asynchronous communications like UART?
baud
5. If a communication hardware block has a FIFO buffer, what does that mean?
Data will be stored and retrieved from the buffer in a first-in, first-out manner, which is
like standing in line to buy a ticket; the first one in line is the first one to finish and
exit the line.
6. Is the following serial communication protocol synchronous or asynchronous?
a) UART?
asynchronous
b) SSI
synchronous
c) I2C
synchronous
7. Sketch the TxD data signal for a UART port transmitting 0xC5. Assume a low start bit and a high
stop bit and no parity bit. Scale your sketch (y-axis) from low (0) to high (1).
