The FMC of Xilinx FPGA is short for FPGA Mezzanine Card. FMC is divided into two parts: processing engine (carrier card) and I/O engine (FMC module). The carrier card and the module are connected by connectors. The connector on the carrier card usually uses a female socket, and the connector on the module usually uses a male socket. Designers can reuse a single carrier card (including one or more FPGAs and an appropriate number of FPGAs). and types of FMC connectors and boards) as the basis for many different markets and applications. At the same time, with the new higher performance and more powerful FPGA products, designers can easily upgrade to new carrier cards while ensuring full compatibility with existing FMC modules.

The FMC standard defines two sizes of single width (69mm*76.5mm) and double width (139mm*76.5mm). Single-width modules support a single connector to the carrier card. Mainly targeted for applications requiring higher bandwidth, more front panel space, or larger PCB area, the double-width modules support up to two connectors. Available in two sizes, the FMC standard provides more flexibility to fine-tune the board based on space, I/O requirements, or both.

Once the size is selected, the board designer has to choose between two different connectors to interface the FMC standard to the FPGA on the carrier card: a low pin count with 160 pins (LPC: Low Pin Count Connector with 160pins) connector, and the other is a high pin count (HPC: High Pin Count Connector with 400pins) connector with 400 pins. Both connectors support single-ended and differential signaling rates up to 2Gb/s, and signaling rates up to 10Gb/s to the FPGA serial connector.

In addition to 68 user-defined single-ended signals or 34 user-defined differential pairs, the LPC connector provides a serial transceiver pair, clock, JTAG interface, and a base Intelligent Platform Management Interface (IPMI) command interface. Select the supported I2C interface. The HPC connector provides 160 user-defined single-ended signals or 80 user-defined differential pairs, 10 serial transceiver pairs, and more clocks.

Both HPC and LPC connectors use the same mechanical connector, the only difference is which signals are actually ported, so cards that use the LPC connector can also be plugged into the HPC, and with proper design, the HPC card can also be plugged into the LPC. Can provide many derived functions.

For detailed specifications, please refer to the relevant standards:

ANSI/VITA 57.1 - Revised2019 FMC: FPGA Mezzanine Cards Base Standard

ANSI/VITA 57.4 - Revised2018 FMC+: FPGA Mezzanine Cards Base Standard - Next Generation

The above is a brief introduction to the FMC for Xilinx FPGA, I hope it can help you reference.