PCIe3.0 to Dual M.2 HAT for Raspberry Pi 5 with ASMedia ASM2806 PCIe 3.0 Switch by Seeed Studio

 Raspberry Pi users have seen different HAT+ boards with multiple M.2 sockets, like the Geekworm X1004 HAT+, Pineboards HatDrive! AI, and HatDrive! Dual, which each have two sockets, or the Geekworm X1011 with four sockets. At first glance, Seeed Studio’s PCIe3.0 to Dual M.2 HAT+ for Raspberry Pi 5 may seem like these older options. However, it stands out because it uses the ASMedia ASM2806 PCIe 3.0 switch, which supports up to 8GT/s shared bandwidth from the Raspberry Pi 5’s PCIe Gen3 x1 interface, while the older boards use the ASM1182e or ASM1184e PCIe Gen2 x1 switches, which max out at 5GT/s shared bandwidth.

The board is mainly designed for the Raspberry Pi 5, but other single-board computers (SBCs) like the Radxa ROCK 5C, ROCK 5C Lite, and Pine64 Quartz64 Zero also have a PCIe FFC connector. However, these boards use PCIe 2.1 x1, so they can't fully take advantage of the faster speeds of the ASM2806 chip.

Key Features and Specifications:

Compatible SBCs: Designed for the Raspberry Pi 5 and other SBCs with a PCIe FFC connector, such as the Kakip board.

M.2 Slots:

• Dual M.2 M-PCIe slots with PCIe 3.0 x1.
• Supports M.2 2230, 2242, 2260, and 2280 modules (e.g., SSDs, AI accelerators).

PCIe Switch:

• Features the ASMedia ASM2806 PCIe 3.0 switch chip.
• Offers PCIe Gen3 x2 upstream (limited to x1 in this design) and four PCIe 3.1 lanes downstream (two lanes used).
• Provides a combined bandwidth of 8 GT/s.

Host Interface:

• Connects via the Raspberry Pi 5 PCIe FFC connector.
• Includes a 50mm S-shaped FPC cable that avoids obstructing the microSD card slot.

Power Supply:

• 5V/3A supplied through the Raspberry Pi 5.
• Additional power:
• 5V/2A via pogo pins.
• 5V/1A via the PCIe connector.

Form Factor:

• Compliant with the Raspberry Pi HAT+ dimensions.

The company has pointed out that there may be compatibility issues with some NVMe SSDs, but if the ASM2806 switch works correctly, there shouldn't be major differences compared to other M.2 PCIe HAT+ boards. They suggest using specific NVMe SSD models, including Foresee 128GB, 256GB, and 512GB, as well as Kioxia 1TB and 2TB, which are all Seeed Studio-branded.

The HAT doesn't fit the official Raspberry Pi 5 case, so Seeed Studio has created a custom 3D-printed case for it. They've shared the STEP file online so anyone can print their own version. On wiki, you'll find clear setup instructions and benchmarks that show how well SSDs perform. The tests highlight the benefits of using PCIe Gen3 instead of Gen2, especially for AI tasks using the Hailo-8 AI accelerator.

The Seeed Studio PCIe 3.0 to Dual M.2 HAT+ is a useful upgrade for Raspberry Pi 5, offering faster speeds, but it’s limited by the PCIe Gen3 x1 bandwidth. More powerful SBCs, like those with the Rockchip RK3588, can support faster PCIe Gen3 x4 speeds. The Seeed Studio PCIe 3.0 to Dual M.2 HAT+ is priced at $45 on the company’s website. It’s the first expansion board using the ASM2806 chip for Raspberry Pi 5, with more options, like the RPI5 PCIe Hub, coming soon. Overall, it boosts performance for Raspberry Pi users wanting better speed and functionality.