UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

cancel
Showing results for 
Search instead for 
Did you mean: 
Highlighted
Visitor ivictbor
Visitor
9,902 Views
Registered: ‎03-27-2014

Can't config FPGA from flash after power OFF and ON

Hi, I have 2 devices with the same schematic, which use xc3s500. First device configures perfectly after power off and on.

And second configures normal only after programming in impact(I selected option "automaticly load fpga with flash contents after programming" ), but fails after power off and on. M3M2M3 for both devices is 001.

I captured flash spi signals for both divices:

 

So in right diagram FPGA generates 0xFF MOSI byte, and I think this is the issue, but why? And how can it be that device configured from flash sucesessfully after programming in impact but fails after power off/on? Thanks.

 

Tags (4)
0 Kudos
8 Replies
Historian
Historian
9,887 Views
Registered: ‎02-25-2008

Re: Can't config FPGA from flash after power OFF and ON

Do you have a power-supply/reset supervisor chip driving the FPGA's PROGRAM_B line?

----------------------------Yes, I do this for a living.
0 Kudos
Visitor ivictbor
Visitor
9,883 Views
Registered: ‎03-27-2014

Re: Can't config FPGA from flash after power OFF and ON

PROG_B Line is unnconected (open) for both devices

0 Kudos
Historian
Historian
9,881 Views
Registered: ‎02-25-2008

Re: Can't config FPGA from flash after power OFF and ON


@ivictbor wrote:

PROG_B Line is unnconected (open) for both devices


Well, you need to make sure that PROGRAM_B is held low until after all power supplies have stabilized. You do that with a reset supervisor.

----------------------------Yes, I do this for a living.
0 Kudos
Visitor ivictbor
Visitor
9,877 Views
Registered: ‎03-27-2014

Re: Can't config FPGA from flash after power OFF and ON

Many thanks! I will try to manualy drive this pin. 

0 Kudos
Historian
Historian
9,864 Views
Registered: ‎02-25-2008

Re: Can't config FPGA from flash after power OFF and ON


@ivictbor wrote:

Many thanks! I will try to manualy drive this pin. 


The reason I recommend the reset supervisor is that your power-on/off sequence is making the supply rails come up weirdly and as such the FPGA's internal configuration-start logic gets confused. A reset supervisor ensures that you don't start configuration until well after all supplies are settled.

----------------------------Yes, I do this for a living.
0 Kudos
Visitor ivictbor
Visitor
9,843 Views
Registered: ‎03-27-2014

Re: Can't config FPGA from flash after power OFF and ON

I connected PROG_B to GND for 1 second, after minutes of power supply(I think all supplies are settled), and then disconnected it, but unfortunately behevior is same: first MOSI byte is FF. Thank you for attempt to help.

0 Kudos
Historian
Historian
9,785 Views
Registered: ‎02-25-2008

Re: Can't config FPGA from flash after power OFF and ON


@ivictbor wrote:

I connected PROG_B to GND for 1 second, after minutes of power supply(I think all supplies are settled), and then disconnected it, but unfortunately behevior is same: first MOSI byte is FF. Thank you for attempt to help.


Are you sure the configuration memory is not blank?

----------------------------Yes, I do this for a living.
0 Kudos
Visitor ivictbor
Visitor
9,671 Views
Registered: ‎03-27-2014

Re: Can't config FPGA from flash after power OFF and ON

After programming in IMPACT blank check says that it is not blank. Verify say that it is ok. And at once after programming configures normal, but after power On it is not work.

In first message I showed diagrams of flash spi signals, as you see first MOSI byte (generated from FPGA SPI Master interface) uncorrect, so content of flash irrelevant for this problem.

0 Kudos