The Osmocom SFP experimenter board a small circuit board for experiments with (usually fiber optical) transceivers in SFP form factor.

You can use it for e.g.
  1. 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
  2. attach some I2C adapter to the I2C pins of the SFP module in order to re-program it
  3. 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.

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.

Schematics / Design files

The schematics / design files are kept in git at

You can see the design discussion in #3314 and notes from board-bringup at #3523



As this is an Open Source Hardware design, you can simply go ahead and build the boards yourself using the design files we released.

Assembled boards are made available via the sysmocom webshop


sfp-experimenter v2

None known so far.

sfp-experimenter v1

R6 pull-down re-work

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.

Files (7)
sfp-experimenter-r6-rework.jpg View sfp-experimenter-r6-rework.jpg 80.9 KB laforge, 10/07/2018 06:49 AM
sfp-experimenter.jpg View sfp-experimenter.jpg 189 KB laforge, 10/07/2018 06:49 AM
sfp-experimenter.pdf View sfp-experimenter.pdf 45.1 KB sfp-experimenter.pdf v1 schematic mschramm, 01/08/2019 03:48 PM
P3050287_1600.jpg View P3050287_1600.jpg 853 KB laforge, 03/14/2019 08:06 PM
P3050290_1600.jpg View P3050290_1600.jpg 877 KB laforge, 03/14/2019 08:06 PM
P3050292_1600.jpg View P3050292_1600.jpg 765 KB laforge, 03/14/2019 08:06 PM
P3050294_1600.jpg View P3050294_1600.jpg 587 KB laforge, 03/14/2019 08:06 PM

Updated by laforge almost 2 years ago · 7 revisions

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