XCFxxP Plaform Flash Device Questions

Hi,

Was wondering if anyone has used the XCFxxP devices with revision selection controlled via the internal REVSEL bits rather than the external REVSEL pins?

I'm assuming the REVSEL bits are, once programmed, persistent (non-volatile), yes? Is it possible to re-write the REVSEL bits without having to download a new bitstream as well?

Finally, can anyone see a problem with the FPGA bit-bashing the JTAG on the PROMs to re-program both bitstreams and REVSEL bit settings? And what about the FPGA sending the CONFIG command to the PROM to initiate a re-configuration of itself?

TIA Regards,

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Mark McDougall, Engineer
Virtual Logic Pty Ltd, 
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Mark McDougall
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I haven't used any of the revsel features, so I can't answer that part, but I have used the config command to re-config an fpga (where I forgot to connect the prog line) and it works just fine.

But I think it would be better to use the prog line to initiate re-config.

Alan Nishioka

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Alan Nishioka

CONFIG was sent from/via the FPGA itself?

Momentarily forgot about that option - thanks!

Regards,

--
Mark McDougall, Engineer
Virtual Logic Pty Ltd, 
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Mark McDougall

Where did you read that REVSEL are non-volatile??

To my knowledge the XCFxxP can not be used to implement safe multiboot triggered by the FPGA without using external non-volatile logic kludge

- Xilinx has some appnotes using coolrunner to control the REVSEL and reboot

Antti

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Antti

Yes. I always connect the jtag lines back to io lines for true field programability. Usually, I rely on power cycling to reload the configuration. But this app required reconfig without user intervention. So I wrote a little state machine to send the jtag config command to the prom.

I also considered sending the jtag sequence to the fpga to toggle the prog pin, but I figured config was easier.

But in my next design, I am going to connect the prog pin to an io line.

Alan Nishioka

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Alan Nishioka

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