Bus access conflicts In a shared bus system, what condition arises when two or more sources attempt to drive the same bus lines at the same time?

Introduction / Context:Shared buses require arbitration to prevent multiple drivers from asserting conflicting logic levels simultaneously. When arbitration fails or is absent, electrical conflict occurs, risking data corruption and hardware damage.

Given Data / Assumptions:

• Multiple potential bus masters or devices can drive the bus.
• Tri-state buffers or open-collector/open-drain schemes are used to allow sharing.
• Arbitration/enable control should ensure only one active driver at a time.

Concept / Approach:“Bus contention” describes the event where more than one driver actively drives the bus. This can cause excessive currents (e.g., one device drives HIGH, another drives LOW), noise, and logic errors.

Step-by-Step Solution:Identify conflict scenario → simultaneous drivers.Name the condition → bus contention.Relate mitigations → arbitration logic, proper enable timing, pull-ups for open-collector.

Verification / Alternative check:Hardware debug often reveals contention by observing abnormal current draw and distorted waveforms; logic analyzers show overlapping drive windows.

Why Other Options Are Wrong:

• Direct memory access: a controlled transfer method, not a fault.
• Bus interruption: vague; not the standard term.
• PPI: stands for programmable peripheral interface, unrelated to the fault.

Common Pitfalls:Forgetting to tri-state outputs during reset or handover; incorrect chip-enable timing.

Final Answer:Bus contention