32 lines
1 KiB
Markdown
32 lines
1 KiB
Markdown
---
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title: Meet the Quadrature Encoder
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summary: Learn what the A and B channels are and why their phase offset lets you count motion.
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chapter: Reading Encoder Signals
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order: 1
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tags:
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- encoders
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- motors
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- feedback
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estimated_minutes: 8
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---
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# Meet the Quadrature Encoder
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A quadrature encoder gives you two square-wave signals, usually called `A` and `B`.
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Those signals toggle as the shaft turns. The important detail is that they do not toggle at the same time. One channel leads the other by a quarter of a cycle, which is where the name quadrature comes from.
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That phase offset gives you two useful facts:
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1. You can count edges to measure motion.
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2. You can compare which signal leads to determine direction.
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## What you should observe
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- Slow rotation produces clean transitions you can inspect with a logic analyzer.
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- Reversing the shaft swaps which channel leads.
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- More pulses per revolution means finer position measurement.
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## Checkpoint
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Capture both channels while rotating the shaft by hand and confirm that one channel leads the other.
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