Design Gateway AB20-U2PCI Adapter Board
Design Gateway AB20-U2PCI Adapter Board converts a 16-lane PCI Express interface into four 4-lane PCI U.2 interfaces. The Design Gateway AB20-U2PCI board is compatible with standard Intel (Altera) or AMD (Xilinx) FPGA evaluation boards, allowing evaluation of NVMe IP-Core operations and developing prototypes. The board features four U.2 connectors on the component side for up to four 2.5" U.2 SSDs, and a 16-lane PCIe connector on the solder side. Lanes 3-0, 7-4, 11-8, and 15-12 connect to SSDs at CN1, CN2, CN3, and CN4, respectively. It includes a low-jitter clock generator, reset circuitry, and a 6-pin PCIe auxiliary power supply for the adapter and SSDs. A mechanical support frame secures the U.2 SSDs.
Features
- Expansion adapter board for U.2 SSD with 16-lane PCI Express support
- Read/write access between FPGA and U.2 SSD in PCIe Gen5, confirmed in actual device operation
- Up to four U.2 SSDs under 15mm in height size can be installed simultaneously
- Power is supplied at +12V from a standard external 6-pin PCIe auxiliary power supply
- Power supply to the adapter and U.2 SSD can be controlled ON/OFF with a switch
- PCIe standard 100MHz low-jitter clock source mounted on the adapter
- Supplies 100MHz differential clock signals of the same phase to PCIe and four SSDs
- Reset is selectable between PCIe-SSD direct connection and reset output on the adapter board via jumper socket
Applications
- Data storage
- Networking
- Development for any FPGA-based application
AB20-U2PCI adapter with support frame
Adapter outline
The adapter board with support frame size is 166mm x 60mm x 85mm (WxHxD). The component side and the solder side of the board are shown in the images below.
adapter board component side
adapter board solder side
Power Supply
This adapter's power is supplied by +12V from a 6-pin type PCIe auxiliary power supply. The power switch controls the supply of the adapter and the installed SSD. The power-on status can be checked with the LED next to the power connector. The +12V power supply is used to generate a +3.3V power supply with a regulator inside the adapter, but +3.3V power is not supplied to U.2 SSD or the +3.3V power pin of the PCIe connector. So, a +3.3V power supply to the connected FPGA board via a PCIe connector is impossible.
Access Indicator LED
There is an SSD access LED near each U.2 connector, which emits light when the respective U.2 connector pin P11 (ACTIVITY# signal) is at a low level.
Reset circuit
The adapter contains a reset IC that generates reset signals for PCIe and U.2, a reset switch for manually generating a reset signal, and 2x2 jumper headers for selecting each reset system. The reset IC constantly monitors the voltage level of the +3.3V power supply and outputs a low active reset signal when the voltage level falls below approximately 3.0V. It also generates a reset signal pulse of about 100ms when the reset switch is pressed.
The reset signal connection can be set by inserting a socket into the 2x2 4-pin header JP1. The factory default socket settings are the connections between 1 and 4 and between 2 and 3.
Short between 1 and 4: Connects the reset IC output to reset all 4 U.2 SSDs (Pin# E5).
Short between 2 and 3: Connect the reset IC output to the PCI Express reset (Pin# A11).
Short between 1-2: Connects PCI Express reset (Pin#A11) to all four U.2 SSD resets (Pin#E5).
