Is FMC on zedboard High Pin Count (HPC)?

[Leon18]

I am planning to buy FMC to gpio converter board for my zedboard. I found the board XM105 from AMD was probably the one I needed. However, I am not sure it is compatible with zedboard. Can anyone give me a confirmation? BTW, Is FMC on zedboard High Pin Count (HPC)?

Edited January 2 by Leon18

[zygot]

The Zedboard has an LPC FMC connector. You should review the schematics for the Zedboard and the XM105 to check for compatibility.

The FMC standard is designed so that LPC and HPC sockets are compatible; LPC just has fewer contact pins installed.

Be aware that most of the XM105 signals are single-ended only, even if they are differential on the carrier board. You do get a nice programmable external clock source with the XM105.

[artvvb]

Hi @Leon18,

You can find the user guide, schematics, etc, here: https://digilent.com/reference/programmable-logic/zedboard/start. As Zygot mentioned, it is a low-pin count connector.

Thanks,

Arthur

[zygot]

I've used the XM105 with the Genesys2 (HPC FMC) and the Nexys Video (LPC FMC). I don't know of a reason that the Zedboard couldn't use it as well; but you must do your own due diligence. Don't forget about Vadj when connecting FMC signals from a carrier board to anything.

[Leon18]

On 1/2/2024 at 2:37 PM, zygot said:

The Zedboard has an LPC FMC connector. You should review the schematics for the Zedboard and the XM105 to check for compatibility.

The FMC standard is designed so that LPC and HPC sockets are compatible; LPC just has fewer contact pins installed.

Be aware that most of the XM105 signals are single-ended only, even if they are differential on the carrier board. You do get a nice programmable external clock source with the XM105.

Schematics are not enough since I probably need PCB layout to check these two board FMC ports. Is this FMC male or female on XM105?  I couldn't find any picture for the FMC side of XM105 (AMD only provide photo of XM105 which the FMC can't be seen). Could you upload a picture of the FMC side photo for XM105?

Edited February 2 by Leon18

[zygot]

Leon18: "Schematics are not enough since I probably need PCB layout to check these two board FMC ports."

I'm not understanding what your qualms are. What do you need to check on the layout that the schematic won't show, other than if differential signals are laid out in a proper differential routing scheme? ( the XM105 only supports single-ended for most of it's signals ).

As I mentioned I've used the HPC HW-FMC-XM105-DEBUG board with both the LPC Nexys Video and HPC Genesys2 boards. The Differential Pmod Challenge projects that I published in Digilent's Project Vault provide some information. But I will say that no one should accept anything posted to a forum like this as absolute fact; trust and verify in the words of a past POTUS.

In general, interfaces like HSMC and FMC are carrier/mezzanine board oriented; with one gender assigned to the carrier and the mating version assigned to the mezzanine board. This doesn't mean that there aren't exceptions as some vendors just want to use the connectors and not follow the standards.

The Genesys2, Nexys Video and XM105 board (xtp078.pdf) schematics provides the connector part number. ADM/Xilinx also provides extra information like BOM, PCB information etc. It's up to you, the designer, to go to the connector manufacturer and get specific information. Don't be surprised to discover that for FMC and HSMC there are a lot of connector part number variants, some of which may be specialty parts for specific customers. This is to prevent customers from getting bored.

Regardless of whether or not an FPGA vendor adheres to a standard, it is up to the designer to go through all of pins and verify compatibility between a carrier board and an arbitrary mezzanine board. This is especially important for LVDS and clocking as various FPGA device families have different rules regarding clocking and IO pins. It's no uncommon for a mezzanine board vendor like Ti or ADI to use a pin for some purpose other than what the standard decrees. Also, the signal trace layout rules for pin pairs that might be differential or single_ended are not hard and fast. For a general purpose interface one might need the best possible signalling for one project, but just good enough for a different project. Generally FPGSA carrier board schematics provide not just interface connector pin assignments but IO bank assignments which might be just as important,

Just when I thought that I was done here, I remembered that most high density connectors come in a variety of heights. If you are designing your own board you need to pay attention to these things.
As an aside some newer FPGA boards use the FMC+ specification which is not backward compatible with the FMC connector mechanical dimensions. Edited February 2 by zygot