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Observer rpmiller
Registered: ‎10-17-2017

QSPI flash programming- with a second FPGA


I'm developing a design that is based on the Zynq xc7z100 FPGA.  I'm designing it to boot from QSPI flash just like the zc706 dev board.  I'm also planning on using JTAG and the platform II cable for development.  For the final design, however, I plan on having a second FPGA on board.  This FPGA provides my interface to the outside world and I want to be able to update the Zynq's QSPI memory.  Initially I was thinking of controlling the JTAG to the Zynq and updating the QSPI that way.  I haven't found a lot of detail about this so if someone could point me in the right direction.  I want to be able to do this the first time - that is no program loaded by the Zynq.  Maybe it would be better to give the second FPGA access to the QSPI bus directly.  I'm not sure about this one.  I also thought that I could just connect 2 sets of QSPI chips to the second FPGA and select between them - then connect the Zynq QSPI interface to the second FPGA instead of the QSPI directly.


Any advice or pointers is greatly appreciated.  This is my first Zynq design and this particular aspect isn't really covered by the reference designs.


Thanks again,


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Xilinx Employee
Xilinx Employee
Registered: ‎10-11-2011

Re: QSPI flash programming- with a second FPGA

Driving the JTAG lines to (for example) run an SVF that programs the QSPI is doable but NOT an easy task.

I think MUXing the QSPI with either discrete component or the FPGA itself it's definitely easier.

Just remember that you need to be able to (at least) run the QSPI at ~15MHz from zynq-7000 if you want to be able to boot from it.

Sorry we don't have example designs for this but it's a corner case that we don't usually considered.


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