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... | @@ -47,7 +47,7 @@ provides: |
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### SFP assemblies
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### SFP assemblies
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There are 8 SFP assemblies, each of them including:
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There are 8 SFP assemblies, each of them having:
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- an SFP socket
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- an SFP socket
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- 2 status LEDs
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- 2 status LEDs
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... | @@ -60,6 +60,25 @@ assemly: |
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![](/uploads/cc5629df917a89d78e3e399484d8b05c/mini_backplane_sfp_assembly.jpg)
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![](/uploads/cc5629df917a89d78e3e399484d8b05c/mini_backplane_sfp_assembly.jpg)
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The calibration buffers are placed very close to the SFP connector pins
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to avoid making stubs. The outputs of the buffers are connected together
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between two adjacent SFPs (e.g. SFP0 + SFP1, SFP2 + SFP3, ...) to avoid
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excessively long stubs on the feedback trace. Since the buffer outputs
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are tri-stated, it makes a nice and cheap multiplexer suitable for the
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calibration of the PHY asymmetry.
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All the digital lines (except for the SFP builtin I2C memory) are
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controlled by an 8-bit I2C GPIO expander (PCF9534):
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- P0: Link LED
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- P1: Status LED
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- P2: SFP Tx disable
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- P3: SFP Tx fault
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- P4: Calibration feedback enable for TX path
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- P5: Calibration feedback enable for RX path
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- P6: SFP loss-of-signal
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- P7: SFP detect
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### Files
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### Files
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