Configuration Rate with multiple .bit files

All-

I am combining 2 .bit files into one .mcs for an XCF16P (XC3S1500-676 and XC3S1000-456). In both cases I've set the Configuration Rate parameterto 50. It takes 200 msec for DONE to go high -- that sounds too slow.

Can this be right? Which .bit file takes precedence? Is there something additional that needs to be set?

-Jeff

Reply to
Jeff Brower
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XCS1500 config is 5,214,784 bits XCS1000 config is 3,223,488 bits

( 5214784+3223488 bits ) / 50 MHz = 169ms (as a lower bound)

How much faster do you expect it to be?

Alan Nishioka

Reply to
Alan Nishioka

Alan-

Thanks for your reply.

The first FPGA has a PCI core. We were hoping to boot under 100 msec. Is there a way to go faster than 50 MHz without resorting to external clock + INIT gating circuitry?

-Jeff

Reply to
Jeff Brower

I don't know. This is one of the reasons I have always used external pci bridges. But I thought there was more time during pci config.

All I can think of is using two config proms or using parallel config mode.

Alan Nishioka

Reply to
Alan Nishioka

On that line, what about one of the 150Mbit Winbond SPI memories, and a small CPLD to turn it into parallel-config ?

-jg

Reply to
Jim Granville

oops, that should be 150Mbd, of course....

Reply to
Jim Granville

Alan-

I looked up the PCI 2.3 spec, time to first config access is 2^25 clocks, or about 250 msec at 133 MHz. We have customers though who prize fast turn-on time, so I'm always looking to get under that 100 msec mark.

2 config proms? I wish. The board is jammed -- 16 layers, blind vias, lots of things like 201s and 2x3 mm oscillators. Pic of the board is here:

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Parallel config maybe... need to think about that.

-Jeff

Reply to
Jeff Brower

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