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Sfp-experimenter » History » Version 4

laforge, 03/05/2019 01:55 PM

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h1. sfp-experimenter
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The Osmocom SFP experimenter board a small circuit board for experiments with (usually fiber optical) transceivers in SFP form factor.
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You can use it for e.g.
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# transmitting your own signals / waveforms (not restricted to Ethernet or CPRI) over fiber optics. This is e.g. useful if you need galvanic isolation between digital circuits, or need long-distance transmission
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# attach some I2C adapter to the I2C pins of the SFP module in order to re-program it
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# The SFP transceivers exhibit a symmetric/differencial interface for Rx and Tx. The sfp-experimenter board contains an on-board differential transmitter and receiver so you can transmit/receive normal single-ended signals.
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If you're interested in transmitting differential signals, please see the [[sfp-breakout]] board instead. It's like the SFP experimenter board, but contains no differential transmitter + receivers.
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h2. Schematics / Design files
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The schematics / design files are kept in git at https://git.osmocom.org/osmo-small-hardware/tree/sfp-breakout
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You can see the design discussion in #3314 and notes from board-bringup at #3523
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h2. Photos
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!sfp-experimenter.jpg!
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h2. Availability
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h2. Errata
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h3. sfp-experimenter v1
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h4. R6 pull-down re-work
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there was a need to place a bias resistor from RD_N to ground (pin4 on ic2) or the whole board would not work. ic2 has internal 100ohm prom pin3 to pin4 and pullups of ~300k to vcc. 100k pulldown on one leg pushes it into the proper operating range. due to the 100ohm its not neccessary to have more than one pulldown.
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!sfp-experimenter-r6-rework.jpg!
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