Draft:CRUVI

CRUVI is an expansion bus interface designed to create an open ecosystem of function modules for high-performance peripheral connectivity. Its main focus is on supporting FPGA and FPGA SoC devices from all major manufacturers like Intel ®, Lattice, Microchip and Xilinx.

The word "CRUVI" is a combination of the Estonian word "KRUVI" for screw and the letter "C", which refers to the half of the hexagonal screw head. In this case, the "K" was replaced with "C" to emphasize the reference to the screw head.

Overview
The CRUVI open standard coexists between low speed, low pin-count like Pmod Interface devices and high-performance, high pin-count (HPC), 400 I/O FPGA Mezzanine Card (FMC) peripherals.

It can be used to build high performance prototypes, for system integration and testing to build complex systems from smaller building blocks to iterate quickly and reduce cost. Create custom test systems for production functional testing. It's a perfect platform for your next high-performance semiconductor evaluation boards and systems.

Interface bridging to or from other coexistence ecosystem is possible to do with peripheral modules or boards.

Three board-to-board connectors are specified: CRUVI-LS (Low Speed), CRUVI-HS (High Speed) and CRUVI-GT (Gigabit Transceiver) PCIe Gen 5.0 capable.

Peripheral CRUVI-HS and CRUVI-GT test board with loopback, scope or logic analyzer functions can verify the i.e. high speed connector performance or to be probed signals.

History of CRUVI specification
International contributors to define the open source CRUVI specification are Trenz Electronic GmbH, Arrow Electronics, Samtec, Flinders University, Synaptic Laboratories Ltd, Symbiotic EDA and MicroFPGA UG.

History of CRUVI open source specification – FREE to use Apache License 2.0

Carrier host board specification
Carrier board or host board delivers power supplies, IO voltage and controls the functions of peripheral modules.

Single, double or triple width modules are allowed and they have more mounting holes.

A triple size of space on carrier board (PCB template CR99201) is 67.72 x with LS and HS connectors. There are 3 slots named: AX, BY, and CZ. The mounting holes (1 to 6) for M2 screws are 2.2 mm (0.0866 inch) diameter and need SMD spacer for mechanically fixing.

It is recommended for all FPGA host boards with CRUVI slots provide LiteX platform support files.

Host and carrier boards are available with FPGA´s from Intel ® (TEI0050, TEI0185, CR00010, CR00100, CR00109), Lattice (TEL003, CR00103), Microchip (TEMB0005) and Xilinx (TEBF0707, CR00107).

Bridging adapter exists to convert signals from Pmod to CRUVI-LS (CR00025), from FMC to CRUVI-HS (CR00101, CR00111) and FMC to CRUVI-GT (CR00112).

Peripheral board specification
There are different single peripheral module possible, flexible and scalable by size LS, HS and GT connectors. Mounting holes are for M2 screws 2.2 mm diameter.

It is recommended to have EEPROM with I2C for identification of peripheral module with a specific address number.