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-   -   Configuration Rate with multiple .bit files (http://www.fpgacentral.com/group/showthread.php?t=58305)

Jeff Brower 04-10-2006 11:11 PM

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


Alan Nishioka 04-11-2006 12:09 AM

Re: Configuration Rate with multiple .bit files
 
Jeff Brower wrote:
> 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.


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


Jeff Brower 04-11-2006 01:27 AM

Re: Configuration Rate with multiple .bit files
 
Alan-

Thanks for your reply.

> 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?


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


Alan Nishioka 04-11-2006 03:17 AM

Re: Configuration Rate with multiple .bit files
 
Jeff Brower wrote:
> 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?


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


Jim Granville 04-11-2006 04:06 AM

Re: Configuration Rate with multiple .bit files
 
Alan Nishioka wrote:
> Jeff Brower wrote:
>
>>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?

>
>
> 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.


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

-jg


Jim Granville 04-11-2006 04:07 AM

Re: Configuration Rate with multiple .bit files
 
Jim Granville wrote:

> Alan Nishioka wrote:
>
>> Jeff Brower wrote:
>>
>>> 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?

>>
>>
>>
>> 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.

>
>
> On that line, what about one of the 150Mbit Winbond SPI memories, and

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


Jeff Brower 04-11-2006 06:31 AM

Re: Configuration Rate with multiple .bit files
 
Alan-

> 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.


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.

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


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:

http://www.signalogic.com/sigc5561_ptmc.htm

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

-Jeff



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