Hello,
I recently buy a carrier board te0701 with a te0710 module.
I am trying to connect and route my signals to a FMC card.
However I find something weird with B2B connectors between signals name/number/polarity (see attached screenshot)
For exemple, if I understand correctly, FMC_LA11 on carrier board TE0701 becomes B34_L17 on TE0710 module.
In addition polarity is inverted too, P become N and N become P.
So I tried to invert my FPGA output in my constrant file but as expected Vivado tells me "[Vivado 12-1411] Cannot set LOC property of ports, the positive port (P-side) 'signalname_p' of a differential pair cannot be placed on a negative package pin 'L5' (IOBS)."
I will try to invert my signals before OBUFDS in my design.
My question is, have I correctly understand B2B pins connection ? FMC_LA11_P connected to B34_L17_N and FMC_LA11_N connected to B34_L17_P, for example ?
Anybody know why some pins have their polarity inverted ?
Thank you
Hello,
In some differential pairs have P and N can be swapped, the reason is PCB routing constraints. In this case signal should be inverted before/after OBUFDS/IBUFDS.
Best regards
Oleksandr Kiyenko
Ok thank you to confirme this, I will do that :)