RS0, RS1 may be required for SFPs (not SFP+) with selectable speed, so I'd connect them as well to the FPGA. Greg
On 24 July 2016 at 22:31, j arl <joe.britton....@gmail.com> wrote: > Thanks Greg. That clears things up. Let's choose SFP+ electrical for the > layout. But to start we will use WhiteRabbit compatible SFP transceivers. > This clears the way for testing higher speed transceivers in the future. > > I'd like to update the IO count on the microTCA hardware spreadsheet to > accurately reflect the low-speed IO requirements of SFP+ support > -- see NOTE8 > . By my count it looks like 3 > LVTTL > IO per SFP. > > > I'm looking at the > SFF Specification ftp://ftp.seagate.com/sff/SFF-8431.PDF > > > "The SFP+ low speed electrical interface has several enhancements over > the classic SFP interface (INF-8074i), but the SFP+ host can be designed to > also support most legacy SFP modules. " > > > > low-speed IO to support for ARTIQ > > signal name > > function > > level > > routed to FPGA? > > Tx_Disable > > Transmitter Disable; Turns off transmitter laser output ; When Tx_Disable > is asserted low or grounded the module transmitter is operating normally. > > LVTTL > > yes > > SDA > > 2-wire Serial Interface Data Line, I2C > > LVTTL > > yes > > SCL > > 2-wire Serial Interface Clock, I2C > > LVTTL > > yes > > RS0 and RS1 > > Rate Select 0, optionally controls SFP+ module receiver. RS0 and RS1 are > module inputs and are pulled low to VeeT with > 30 kΩ resistors in the > module. RS0 optionally selects the optical receive signaling rate coverage. > RS1 optionally selects the optical transmit signaling rate coverage. The > host and module may choose to use either, both, or none of these functions. > > > > no > > MOD_ABS > > > > > > no > > Tx_Fault > > is a module output that when high, indicates that the module transmitter > has detected a fault condition related to laser operation or safety. If > Tx_Fault is not implemented, the Tx_Fault contact signal shall be held low > by the module and may be connected to Vee within the module. > > > > no > > Rx_los > > The Rx_LOS signal is intended as a preliminary indication to the host in > which the module is installed that the received signal strength is below > the specified range. If the Rx_LOS function is not implemented, or is > reported via the two-wire interface only, the Rx_LOS contact shall be held > low by the module and may be connected to Vee within the module. > > > > no > > > > > ------- > Joe Britton > Sensors and Electron Devices > Army Research Lab > 2800 Powder Mill Rd > Adelphi, MD 20783 > 301-394-3130 > joseph.w.britton5....@mail.mil > > On Sun, Jul 24, 2016 at 8:04 AM, Grzegorz Kasprowicz <kaspr...@gmail.com> > wrote: > >> >> >> 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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