Hi,
im an sending with an Virtex4-FX 8b10b encoded data at 1.25Gbps. It is working fine in simulation, but the implementation sends incorrect data. (checked with a scope at the MGT output)
Apparently 6-bit sub-characters with no disparity are sent inverted: D.03 is sent as D.28 D.05 is sent as D.26 D.06 is sent as D.25 etc.
As far as I can tell all other charecters (e.g. those with negative of positive disparity) are sent correctly. The MGTs are configured for normal automatic 8b10b encoding. I am only controlling the data pins and txcharisk.
Has anybody seen this before? Any ideas what could cause this? Instable clocks? Incorrect CONFIG STEPPING? Timing Errors?
Thx for your help,
Kolja Sulimma