Digital systems – Definition of a transceiver What is a transceiver circuit in the context of shared digital data buses?

Difficulty: Easy

Correct Answer: a buffer that can operate in both directions

Explanation:


Introduction / Context:
Transceivers are widely used on shared data buses to allow bidirectional data movement while preventing contention. Understanding their role is essential for bus-oriented microprocessor and FPGA designs.


Given Data / Assumptions:

  • A single signal path may need to carry data in either direction at different times.
  • Control signals enable or disable driving the bus to avoid conflicts.


Concept / Approach:
Transceiver = transmitter + receiver in one device. It typically has direction control (DIR) and output enable (OE). When DIR selects A→B, the device drives from side A to side B; when toggled, it drives from B→A. OE places outputs in high-impedance when disabled, isolating the device from the bus.


Step-by-Step Solution:

Recognize the term: 'transceiver' implies bidirectional capability.Identify the option that states operation in both directions.Select the answer that explicitly mentions two-way buffering.


Verification / Alternative check:
Common TTL/CMOS parts such as 74xx245 are marketed as 'octal bus transceivers' and include DIR and OE pins; their datasheets confirm bidirectional buffering as the primary function.


Why Other Options Are Wrong:

  • a buffer that transfers data from input to output: One-direction only.
  • a buffer that transfers data from output to input: Also one-direction only (reversed).
  • blank option: Not applicable.


Common Pitfalls:

  • Confusing a simple buffer/line driver (unidirectional) with a transceiver (bidirectional).
  • Forgetting that high-impedance control is vital to prevent bus contention.


Final Answer:
a buffer that can operate in both directions

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