On 19 July 2016 at 17:47, j arl <joe.britton....@gmail.com> wrote: > Greg, Others, Thinking about using SFP+ on new hardware (Sayma, > Metlino). If SFP+ is backward compatible with SFP, m-labs could > attempt DRTIO using SFP+ transceivers and fall back to > WhiteRabbit-approved SFP as backup [1]. Please confirm the following. > > SFP+ supports higher bandwidth (16 Gb/s) than does SFP (4.25 Gb/s) > Yes
> > SFP+ is mechanically backward compatible with SFP. That is, SFP > transceivers can be plugged into SFP+ cages and fit properly. [0] > yes, The only difference between SFP and SFP+ is that SFP+ have I2C interface while SFP mode is selected by MODDEF pins. Once you connect these MODDEF pin to the FPGA, it doesn't matter if you plug SFP or SFP+ But in most cases you don't have to use this interface and simply leave pullups. I2C is useful in case of multi-speed SFPs or when you need to detect certain transceiver type - each SFP has small EEPROM inside. > > SFP+ is electrically backward compatible with SFP. That is, SFP > transceivers can be plugged into SFP+ cages and work properly. > yes > > Note that ARTIQ does care about deterministic propagation delay across > the transceivers. But the delay can be different from the WR standard > delay. -Joe > > [0] > http://www.molex.com/molex/products/family?key=sfp_and_sfp_interconnect_solutions&channel=products&chanName=family&pageTitle=Introduction > [1] http://www.ohwr.org/projects/white-rabbit/wiki/SFP > > ------- > Joe Britton > Sensors and Electron Devices > Army Research Lab > 2800 Powder Mill Rd > Adelphi, MD 20783 > 301-394-3130 > joseph.w.britton5....@mail.mil >
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