描述

Problem Description:

Is the CRC generated dynamically, and how is it stored and reported

during a CRC readback?

解决方案

This question concerns the reliability of the 4000XL devices. Specifically, how

susceptable is the device is to CRC errors during readback or configuration in

hostile environments? For information on Single Event Upsets, there are a number

of white-papers on support.xilinx.com which discuss this for the 4000/XL devices.

CRC generation:

The CRC signature is generated dynamically from the readback/configuration

stream. However, for readback, if your design has LUT RAMs for example, and

since RAM contents change, the readback CRC will not necessarily match the

configuration CRC. After a CRC signature is generated in the LFSR, it is shifted

out of the LFSR. So, there is no other register to hold the signature. This

reduces the probability of an error by not having a second storage register to

which the CRC is copied.