• VITA 57.1 FMC form-factor height extender card
• Compatible with LPC (low-pin-count) and HPC (high-pin-count) boards
• High-Pin-Count (HPC) VITA 57.1 male connector
• HPC VITA 57.1 female connector
• Full 400-pin direct pass-through connectivity
• Flexible I/O voltage (VADJ) support
• Supports convenient use of non-standard carrier and mezzanine card outlines
• Stackable assembly
• Open-source hardware

The photos below show the bottom side with HPC mezzanine card connector (MC-HPC-10) and top side with HPC carrier card connector (CC-HPC-10).

• Extending board-to-board spacing for FPGA carrier and mezzanine cards
• Facilitating additional I/O expansion during prototyping
• Extending lifecycle of FPGA carrier card FMC connectors in test platforms
• Research and education with FPGAs

The FMC Height Extender is a passive PCB module designed to increase the vertical spacing between an FPGA carrier card and an FMC mezzanine module in compliance with ANSI/VITA 57.1 FPGA Mezzanine Card (FMC) Standard.
It provides a high-pin count (HPC) male connector on one side, and an HPC female connector on the other, routing all 400 pins directly through. This enables enhanced accessibility and flexibility during prototyping or testing of FMC I/O interfaces.
The module is fully compatible with both FMC LPC and HPC modules, ensuring maximum flexibility for all types of designs. In addition to its standard functionality, the height extender also supports the convenient use of non-standard compliant FMC cards. If a carrier card places components inside the forbidden regions defined by the FMC outline, or if a mezzanine module has a larger outline than standard FMC modules, the extender adds mechanical clearance. This allows engineers to combine otherwise incompatible carrier and mezzanine cards without redesigning hardware.

The FMC HPC Height Extender was developed for use in various applications:

Fig. 1: FMC HPC Height Extender

1. Prototyping Support
Use the extender to introduce space for auxiliary circuitry, custom cabling, or debugging access between an FPGA and FMC module.

2. Test Platform Extension
Ideal for testing setups where added clearance mitigates connector crowding or signal integrity issues.

3. Signal Inspection / Access
With increased height, engineers can insert test probes (e.g., oscilloscopes) or wiring between the FMC connectors for monitoring or rerouting signals.

4. Non-Standard FMC Card Integration

Carrier boards with non-compliant layouts:
The extender allows usage of carrier boards that place tall components in the otherwise restricted FMC keep-out zones.
Oversized mezzanine cards:
If an FMC mezzanine exceeds the standard outline dimensions, the extender provides the necessary clearance to fit above the carrier board safely.

The printed circuit board is open-source hardware! You can download the FMC HPC Height Extender Board schematics and PCB layout files in their latest revision from http://www.fmchub.com. The parts list (see tab. 2) is very simple, because it consists of only two parts.

Tab. 1: Parts list of the FMC Height Extender Board.

FMC connector	Samtec part no.	Molex part no.	Description
1. CC-HPC-10	ASP-134486-01	45971-4315	female, baseboard side, High-pin count (HPC), 400 I/O, tin-lead
2. MC-HPC-10	ASP-134488-01	45970-4315	male, mezzanine card side, High-pin count (HPC), 400 I/O, lead-free, 10 mm mated stack height

A description of the signals from the HPC and LPC connector can be found at https://fmchub.github.io/appendix/VITA57_FMC_HPC_LPC_SIGNALS_AND_PINOUT.html.

Pin Mapping:
All 400 pins (rows A-K, pins 1-40) are directly routed through, preserving signal integrity.

HPC Compatibility:
Provides full 400-pin connectivity.

LPC Compatibility:
Supports Low-Pin-Count (LPC) modules, which use a defined subset of the HPC pins. Unused pins remain unconnected when operating in LPC mode.

Voltage Support:
Compliant with carrier card VADJ voltage (1.2 V / 1.5 V / 2.5 V / 3.3 V).

PCB Design:
Passive pass-through with Via-in-Pad design (filled and capped vias) and no additional active components.

The board outline is defined by ANSI/VITA 57.1 standard for single width FMC modules. The board was designed with minimal outline, such that absolute board dimensions are 21.00 mm x 69 mm. Exact dimensions are given in figure 2.


Fig. 2: Mechanical drawing of the FMC HPC Height Extender Board.

Form Factor:
ANSI/VITA 57.1 single-width FMC module

Board Dimensions:
To match standard FMC size (21 mm × 69 mm)

Mounting Holes:
Plated, standard positions per VITA 57.1; no electrical connection

Clearance Provided:
10 mm mated stack height

Mounting Kit (included):
Two 10 mm spacers, two screws, and two nuts for secure mechanical attachment between carrier and mezzanine cards.