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Statement of Volatility for Cmod A7


Iceman2020

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Hi @Iceman2020,

...So I did. I have updated the original posting (direct link to post).

For my own personal curiosity, what are the Statements of Volatility needed for? The only non-volatile memory that users should typically interact with is the flash memory, but that can be easily over-written with a different board configuration or erased entirely, and messing with the EEPROM usually results in bricking the board such that it can't be recognized by the Xilinx software and can no longer be configured. If a known working configuration is needed, there are a number of examples including the out-of-box designs available on the Digilent GitHub (link).

Thanks,
JColvin

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On 8/17/2020 at 4:13 PM, JColvin said:

Hi @Iceman2020,

...So I did. I have updated the original posting (direct link to post).

For my own personal curiosity, what are the Statements of Volatility needed for? The only non-volatile memory that users should typically interact with is the flash memory, but that can be easily over-written with a different board configuration or erased entirely, and messing with the EEPROM usually results in bricking the board such that it can't be recognized by the Xilinx software and can no longer be configured. If a known working configuration is needed, there are a number of examples including the out-of-box designs available on the Digilent GitHub (link).

Thanks,
JColvin

Hi @JColvin, I need additional information. The USB controller circuit is a black box. So how exactly would the EEPROM be accessed by a user? Also, the doc references a Digilent API. Where is the API and can a user revert the EEPROM contents to factory default?

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On 9/9/2020 at 3:40 PM, Iceman2020 said:

Hi @JColvin, I need additional information. The USB controller circuit is a black box. So how exactly would the EEPROM be accessed by a user? Also, the doc references a Digilent API. Where is the API and can a user revert the EEPROM contents to factory default?

Hi @JColvin, the Xilinx 7-series product selection guide lists the distributed RAM as 400 kb for the XC7A35T. Also the last entry in the volatility statement still calls 1CSG326C instead of 1CPG236C. Can you please revise?

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Hi @Iceman2020,

You can access the EEPROM through an executable provided by Digilent staff on a case-by-case basis which has a "wizard" to reset the EEPROM back to factory defaults by properly selecting the correct connected board and board type via the USB connector. Digilent otherwise does not provide details on the USB controller (which would normally be present on the intentionally blank page of the board's schematic).

Alternatively, the EEPROM can be accessed via USB through other freely available 3rd party applications such as FT_PROG, though as hundreds of customers have learned, this can easily result in erasing or corrupting the embedded EEPROM such that the board is no longer detected or programmable by Xilinx software, usually turning the board into a paperweight.

I have gone through the two documents again, hopefully having corrected the errors related to the naming of the FPGA part and it's associated RAM values this time and not listing the values for a different Artix 7 IC.

Thank you,
JColvin

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