Realtek Ameba-D RTL872 D Series User Manual page 457

For some encoder, index output high in idle states. In this case, software can configure IDX_INV to suite different encoder. Fig 21-10 illustrates
inverse index pulse case.
PHA
PHB
IDX
Direction
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PC
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Index pulse
detection
RC
PHA
PHB
IDX
Direction
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PC
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Index pulse
detection
RC
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Ameba-D also supports auto-index mechanism, which means it can directly execute the index functions without any setting. This auto-index
mechanism is related with index phase. When the default phase is low, the index pulse detection is the rising edge in the positive direction. The
index pulse detection is the falling edge in the negative direction. When the default phase is high, the index pulse detection is the falling edge
in the positive direction. The index pulse detection is the rising edge in the negative direction.
User Manual
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Fig 21-9 IDX_INV = 0, position counter reset on (PHA, PHB) = (1, 0)
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Fig 21-10 IDX_INV = 1, position counter reset on (PHA, PHB) = (1, 0)
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Quadrature Decoder (Q-Decoder)
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© REALTEK 2019. All rights reserved.
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