Counter: Identifying Count Type from Waveform
Hardware debugging often requires identifying the architecture of an undocumented counter by observing its state transitions on a logic analyzer. Each counter topology produces a distinct bit-change signature across its clock cycles.
The waveform trace below captures eight consecutive clock cycles of a synchronous 3-bit counter. The outputs are captured as Q2, Q1, and Q0, where Q2 is the most significant bit.
| Clock Cycle | Q2 | Q1 | Q0 | | ----------- | ---- | ---- | ---- | | 0 | 0 | 0 | 0 | | 1 | 0 | 0 | 1 | | 2 | 0 | 1 | 1 | | 3 | 0 | 1 | 0 | | 4 | 1 | 1 | 0 | | 5 | 1 | 1 | 1 | | 6 | 1 | 0 | 1 | | 7 | 1 | 0 | 0 | | 8 | 0 | 0 | 0 |
Analyze the state transitions to determine the counter topology. Identify the diagnostic criteria that rule out alternative architectures.
Constraints
- The counter is fully synchronous and triggered on the rising edge of the clock.
- The sequence repeats infinitely after Cycle 8.
- Read the state as a 3-bit vector
Q2 Q1 Q0.
Topics
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