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Visitor
Visitor
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Registered: ‎07-23-2018

SPI Flash Boot

Hi

I am using custom board FPGA (XC7A35T) and SPI flash device for booting (S25FL127SABMFI101)

Here FPGA is bootlading from SPI flash mode.

The question is, After programming the SPI flash, how to reset internaly or any other option in HW/SW instead manually using the Program pin to reset the FPGA.

This board has only FPGA no other external controller present to reset the device.

Thanks in advance

Sruthi

 

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Registered: ‎07-23-2019

Re: SPI Flash Boot

 

I suppose what you have is a JTAG pod, you program the flash and then you want the FPGA to boot that config, right?

Well, I think the only ways are:

- The PROG_B pin, either with a button press or whatever circuitry pulls it down momentarily

- Power cycle

I've noticed sometimes booting doesn't happen if the JTAG pod is on, I always take it out 

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Visitor
Visitor
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Registered: ‎07-23-2018

Re: SPI Flash Boot

Yes you are right, I am using JTAG pod and boot from SPI flash.

As you mentioned , I would like to go with the "PROG_B pin, circuitry pulls it down momentarily" option. 

Could you please provide any reference/example design which pulls down circuit momentrally the program pin ?

Thanks

Sruthi

 

 

 

 

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Moderator
Moderator
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Registered: ‎06-05-2013

Re: SPI Flash Boot

You can use ICAP to trigger reconfiguration via IPROG command. Check the following post https://forums.xilinx.com/t5/FPGA-Configuration/Full-reprogrammation-in-HDL-equivalent-to-PROG-B/td-p/764387

-Harshit
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214 Views
Registered: ‎07-23-2019

Re: SPI Flash Boot

@sruthi_s1 

These little hw bits I thing fall out of this forum, but anything from the good old 555 (do they still make it?) to a tiny microcontroller in SOT23, or even a witty circuit with discrete BJTs will do... it's all very custom and up to you, I feel