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TMS320C6678: Compatible back-plane for PciE for C6678

Ronen Oscar
Intellectual 365 points

Part Number: TMS320C6678
Other Parts Discussed in Thread: TMDXEVMPCI

Hi all,

We are trying to use C6678 as Route Complex (RC) and we are looking for a compatible PciE back-plane.

Is there a specific back-plane that we should use ? We are using PciE Gen 2 2 Lane with 1 EP.

Or are there any general limitations we need to take into account?

Thanks in advance,

Ronen

  • 0
    TI__Guru**** 161600 points

    Hi Ronen,

    There is no specific back-plane recommendations.

    Everything that you need to follow when doing the PCIe desing on your board is described in the Hardware Desing Guide & Device Datasheet:
    www.ti.com/.../sprabi2c.pdf
    www.ti.com/.../tms320c6678.pdf
    You should also take into account the PCIE base specifications, see 6.6 Peripheral Component Interconnect Express (PCIe) in the Hardware Design Guide.
    There are no specific recommendations (or limitations) listed in these documents.
    I've also pinged the design team to elaborate if needed.

    Best Regards,
    Yordan

  • 0 in reply to Yordan Kovachev
    Intellectual 365 points
    Thanks Yordan!

    Do you have any example for a back-plane that worked for you (in case you used a back-plane for c6678).
    Because we tried a two kinds of back-planes with bad results - especially for the case that C6678 is Route complex.

    Best,
    Ronen
  • 0 in reply to Ronen Oscar
    TI__Mastermind 46460 points

    Ronen,

    Your question is a system design question.  There are many aspects of this that must be resolved to have a working system.  If you search E2E regarding C6678 and PCIe system debug, you will find many useful discussions.

    You mention that you want to use the C6678 as the PCIe Root Complex.  This also implies control for the reset to control enumeration and also potentially sourcing the PCIe clock.  PCIe also allows for independent clocks but this prevents use of spread spectrum clocking.  These need to be considered regarding the backplane.  There are also system boot concepts regarding power enabling based on system features and requirements that must be considered.

    Let's back up a step.  What are you trying to do with the PCIe?  Is it a data or control link?  What other processors exist in this system?  Why is the C6678 being considered as the Root Complex?  If the C6678 is being used as a co-processor, it is normally connected as a PCIe End Point.

    Are you trying to set up a prototype using off-the-shelf hardware?  The C6678 EVM is in the MicroTCA form factor.  You can purchase MicroTCA system backplanes with a controller that supports PCIe integration.  There are numerous E2E threads that discussion MicroTCA integration.

    You can also use the C6678 EVM with our PCIe adapter to plug it into an ATX computer backplane.  This adapter is the TMDXEVMPCI available at: www.ti.com/tool/tmdxevmpci There are E2E discussions that mention special concerns for controlling the reset and for properly configuring the clock.

    Our EVM manufacturer Advantech makes PCIe plug-in boards that plug into PCIe backplanes with either 4 or 8 C6678 DSPs.  Please see this link: www.advantech.com/products/pci-express-dsp-cards/sub_half-length_pcie_card1

    Tom

  • 0 in reply to Tom Johnson 16214
    Intellectual 365 points
    Hi Tom,

    Thanks for the answer!

    1 ) The DSP is used as host cpu and used as Root Complex.
    2) The DSP is connected through PCIe to FPGA. (The FPGA is the End Point)
    3) We are using the EVM6678 & FPGA EVM to integrate the PCIe.

    Can this backplane work www.onestopsystems.com/.../pcie-x8-10-expansion-backplane-184 ?


    Thanks in advance,
    Ronen
  • 0 in reply to Ronen Oscar
    TI__Mastermind 46460 points

    Ronen,

    I cannot provide a definitive recommendation for devices not sold by TI.

    From the information available at that link, I cannot tell if it will suffice.  I would need to see a schematic to see how it handles power distribution, reset control and clock distribution.  However, you do not need a backplane to integrate 2 EVMs over PCIe.  You can cable them directly.  What interface does the FPGA have for PCIe?  Is it a male or female PCIe edge-card or is it SMA connectors.  The TMDXEVMPCI provides a male edge connector for the C6678 EVM.  Alternately, the EVM has a standard AMC edge card interface for ATCA and MicroTCA integration.  Another option is use of the SMA-AMC Ultra 9000 from Silicon Turnkey Express silicontkx.com.  This breakout board provides access to the PCIe connections using SMA connectors which most FPGA EVMs also contain.

    You still need to resolve the reset control for enumeration and the PCIe clock distribution.  I am sure both EVMs have independent power sources.  You will need to provide a robust digital ground between the EVMs.  PCIe devices can operate on independent, narrow-band clocks.  This is supported in the C6678 EVM.  Is this also supported in the FPGA EVM?

    Tom