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Visitor nahmed
Visitor
481 Views
Registered: ‎01-15-2019

XAPP058: Reading the state of the chip on the JTAG chain

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Hello everyone,

I was reading through XAPP058 and was wondering apart from programming an FPGA and CPLD using an microcontroller, is it possible to read out the state and info of a chip in the JTAG chain as well?

Thanks for the help

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Xilinx Employee
Xilinx Employee
478 Views
Registered: ‎06-21-2018

Re: XAPP058: Reading the state of the chip on the JTAG chain

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Hi Nahmed,

Yes. It seems like you just need to create an SVF that does that and execute it.

Thanks,
Andres

 

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Xilinx Employee
Xilinx Employee
479 Views
Registered: ‎06-21-2018

Re: XAPP058: Reading the state of the chip on the JTAG chain

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Hi Nahmed,

Yes. It seems like you just need to create an SVF that does that and execute it.

Thanks,
Andres

 

Visitor nahmed
Visitor
437 Views
Registered: ‎01-15-2019

Re: XAPP058: Reading the state of the chip on the JTAG chain

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Hi Andreas,

Thanks for the prompt reply.

Just a followup question. Does the provided sample C code have the capability to handle that commnad or do we need to develop our own code for that purpose?

Thanks

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Xilinx Employee
Xilinx Employee
424 Views
Registered: ‎08-10-2008

Re: XAPP058: Reading the state of the chip on the JTAG chain

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You don't need to modify the C code. All the commands are included in the SVF file. The C code just plays this SVF file. 

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Xilinx Employee
Xilinx Employee
384 Views
Registered: ‎06-21-2018

Re: XAPP058: Reading the state of the chip on the JTAG chain

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Along the same lines of what @iguo mentioned, you can play the SVF files on iMPACT first, in order to make sure they work as expected.

Let us know if you need further help.

Thanks,

Andres

Visitor nahmed
Visitor
337 Views
Registered: ‎01-15-2019

Re: XAPP058: Reading the state of the chip on the JTAG chain

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Thanks for the help.

 

Just a related question. Would the data/configuration read back from the chip be in a file format that can readily be used to program another chip with the exact same configuration or do we need to tweak it a bit?

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Xilinx Employee
Xilinx Employee
324 Views
Registered: ‎06-21-2018

Re: XAPP058: Reading the state of the chip on the JTAG chain

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Hi Nahmed,

Are you trying to read back an FPGA and use that to program another one? I'd recommend using the bit file, provided that you have it.

What device are you trying to read back? Not all the FPGAs allow this.

Thanks,
Andres

 

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Visitor nahmed
Visitor
317 Views
Registered: ‎01-15-2019

Re: XAPP058: Reading the state of the chip on the JTAG chain

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I am trying to read back XC2C256 CoolRunner-II CPLD. But yes, i am trying to read back the CPLD and then use it to program another CPLD.

 

Thanks

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Xilinx Employee
Xilinx Employee
309 Views
Registered: ‎06-21-2018

Re: XAPP058: Reading the state of the chip on the JTAG chain

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Hi,

You should be able to read back the Jedec file, if it's not protected, and program it into another XC2C256.

Thanks,

Andres