IPIF interface not fast enough

I've a project with a powerpc and some userperipherals (connected through ipif at the plb bus). The plb bus is running at 100 MHz and the powerpc is running at 200 MHz. In a virtex2pro vp30 device (speed grade

5) this design is giving no problems with building (all timing constraints are met).

Now I changed the design to use it in a virtex4fx60 (speed grade 10). The plb bus frequency is increased to 125 MHz and the powerpc to 250 MHz. Now I get timing errors. Is this unexpected? (I mean it's only an increase of 25 percent, but the used device is a virtex 4; I was expecting that this small frequency change shouldn't give any problems for a virtex 4).

Does anyone have experience with running the plb bus at 125 MHz and using the ipif interface?

TIA, Frank

Reply to
Frank van Eijkelenburg
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The last EDK I worked with was 3.2, and I was using a Virtex 2 Pro, but "back then" it said in the documentation (the PDF you get when you open the documentation in the graphical editor) that the maximum frequency for the PLB is 100MHz, so I never even tried going faster.

Don't know where the restriction comes from, though, i.e. if it has something to do with the FPGA fabric not being fast enough (in that case a V4 should be better) or the CoreConnect-IP...

cu, Sean

Reply to
Sean Durkin

Documentation for PLB bus indicates a frequency between 141 MHz and 194 MHz (for a virtex 2 pro -7). Documentation for the IPIF interface indicates a frequency between 101 MHz (using all services) and 189 MHz (for a virtex 2 pro -6). This is documentation that belongs to edk 7.1. Since the used ipif interfaces in my design won't use special services (only burst support is used), I expect it shouldn't be any problem?!


Reply to
Frank van Eijkelenburg

The speed of the PLB bus is highly dependent on the number of devices attached to it. I have a V2P50 -5 with a PLB SDRAM, PLB EMAC, PLB to OPB Bridge and a PLB IPIF. I have extensively floorplanned with PlanAhead and I can just barely run at 100MHz.

Joe Samson (jsamson@)
Pixel Velocity
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Reply to
Joseph Samson

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