Connect pcam-5c to Zybo Z7 and Zedborad

[RggBer]

Hi Digilent team,

   I try to connect pcam-5c to Zybo Z7 by its J2 and use MIPI csi-2 rx subsystem IP core provided by xilinx. Refer to Zybo-Z7-Master.xdc, the dphy_xxxx_lp_n/p signals are defined as HSUL_12 IO standard. HSUL_12 is typically considered as single ended IO, why these are _n/p definitions in XDC file which usually considered as diff signal type.

  The same question to connect FMC Pcam Adapter to Zedboard by its FMC. Does level shift IC on FMC Pcam Adapter affect IO definition to lp_n/p signals?

[zygot]

Sometimes, the IOSTANDARD constraints in master .xdc files is confusing.

If you look at the schematic for the ZYBO-Z7 you will see that the Mipi connector signals are connected to IO bank 35 which has a Vccio of 3.3V. Looking at Xilinx literature for compatible IOSTANDARD settings for Bank 35 shows that TMDS-33 is the only differential possibility for such a design. So what's going on here?

Being curious about this is well founded. The ZYBO-Z7 Reference Manual references XAPP894 as the rational for the ZYBO-Z7 Mipi interface design. I suggest that you read that document, though it probably won't answer all of your questions. You can also refer to the Xilinx Series SelectIO Reference Manual for more information.

I think that this is one of those features that deserves more detailed design documentation than Digilent normally provides. Potential users of the board should be asking for a list of qualified Mipi Csi-2 sensors that are guaranteed to work, in all modes, with this board. The same question would be appropriate for the PMOD pcam-5c product. Potential buyers should be given enough information to make an intelligent purchase choice. It may be that having one sensor option is OK; it may be that it isn't.

The reference manual also makes it clear that in order to use the pcam-5c an limited time evaluation license for Xilinx IP is required. This also may or may not be a problem for users. I'd prefer that such hardware come with free vendor created IP. Other people will likely have a different opinion.

Edited January 14, 2023 by zygot