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Programming FPGAs with FLASH

Hi there,

currently I am designing an FPGA board, featuring two Xilinx Virtex-4 FPGAs. It should be possible to program them with onboard Xilinx Platform FLASH PROMs as well as via JTAG with the IMPACT software. For ease of use and debugging all components should be part of one coherent JTAG chain.

Now I'd like to know HOW to connect two FPGAs and two Platform FLASH devices in one JTAG chain so that each FPGA can be programmed through the associated FLASH? How is the identification done (i.e. which FLASH is associated with which FPGA?!)?

Thanks alot in advance...

Regards

Toni

Reply to
Toni Merwec
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Hi.

I've done this several times in the past.

Tie all the TCK and TMS signals in parallel. Tie each TDI to the next TDO. In your case it would be wise to tie the TDO signal from the Flash to the TDI of its FPGA, then tie the TDO signal of that FPGA to the TDI signal of the next Flash, etc. The JTAG connector will have the first flash TDI on a pin and the 2nd FPGA TDO as a pin.

Impact will recognize the chain and show icons for each device. You select the flash you want to download your config file to, and Impact will write to that memory, only.

Make sure you have the proper version of Impact and the proper version of the JTAG programming cable. Impact is very picky about cables and software versions.

Hope this helps, Tom P.

Reply to
tlbs101

The FPGA's serial configuration busses should be connected in series if you use one FLASH device. You let Impact create a bitstream with 2 FPGA designs. Load this bitstream into the flash rom and you're ready to load the FPGA's. If you want to use 2 flash devices, connect the TDO and TDI from the flash devices in series. Impact will see the 2 devices in series and you can assign a file to each of them.

BTW, if you have some sort of microcontroller on your board, it might be easier / more convenient / cheaper to load the FPGAs from flash connected to the microcontroller.

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Reply to
Nico Coesel

The devices should be displayed by their physical location in the chain. So you daisy chain the TDI/TDO pins in the physical position you want them to be displayed on screen. That's all you can really do if you have more than one of the same device on the chain.

Dave.

Reply to
David L. Jones

"tlbs101" schrieb im Newsbeitrag news: snipped-for-privacy@22g2000hsm.googlegroups.com...

Okay, thank you very much. I've done it that way now. But one more question: What about the DO pins from the PROMs to the FPGA. In the Platform Flash In-System Programmable Configuration PROMs data sheet ds123.pdf (page 18) it is recommended to tie the DO outputs of both PROMs together and connect the FPGAs in series. I don't see any reason to do it this way. What I would have done normally (without having read the user guide) is having the DO of one PROM connected to one FPGA (DIN) and the other DO of the second PROM to the the other DIN of the remaining FPGA. What is the reason not to do so, i.e. is there any reason? Any help is highly appreciated!

Regards

Toni

Reply to
Toni Merwec

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