NEWSRaspberry Pi Compute Module 4 (CM4) adds four Mini...

Raspberry Pi Compute Module 4 (CM4) adds four Mini PCIe slots


Waveshare’s latest IO carrier board is equipped with the Mini PCIe slot on the Raspberry Pi Compute Module 4.

Raspberry Pi Compute Module
(Image credit: Waveshare)

We’re big admirers of raspberry pi Compute Module 4 (CM4). The addition of the PCIe slot has opened the door to a myriad full of potential (which Jeff Geerling is currently exploring); however, what happens is the best option if you want to have, for, say, 4 PCIe slots? Happily, Waveshare has decided to do something about this as it releases the PCIe-Packet-Switch-4P, brought to our attention by CNX-Software, that uses an ASMedia ASM1184e PCIe switch to connect four devices to the CM4’s single-lane PCIe Gen 2 interface.

Raspberry pi compute module
(Image credit: Waveshare)

However, it’s unlikely to allow you to reach typical GPU speed and be limited further, as the Chinese-language Wikipedia that is part of the board claims that the bandwidth is 500Mbps. This seems not to have zero and could be a mistake.

This IO carrier board is 3.2in and 1.5 inches (82 39mm) and requires a 12v power source. It can be supplied via the PCIe bus or the DC Jack. If no 12v is found, a 5v power source is a viable alternative. Still, the board is accompanied by instructions that indicate that the 5v supply can be redirected into the 12v rail, and measures must be observed to assure proper operation of the board in these circumstances. Unfortunately, the manual does not provide any details on accomplishing this. However, we can keep what appears to be a “floppy drive” power connector which can support 5v and 12v on the bottom of the board.

The PCIe-Packet-Switch-4P is an add-on board that connects to a Compute Module 4 IO carrier board that already has a single Mini PCIe slot exposed. The board is inserted inside the Mini PCIe slot and is secured by brass standoffs. It’s also compatible with other Mini PCIe compatible carrier boards, such as the one on the Waveguide’s CM4 carrier card, which includes HDMI, Ethernet, USB ports, GPIO and three ribbon cables connectors.

Cards compatible with Raspberry Pi over PCIe include USB 3 controllers, SSDs, SATA interfaces, Ethernet controllers, and Creative’s Sound Blaster Extreme X-Fi sound card. In addition, pi maker and friend of Tom’s Hardware Pi cast Jeff Geerling maintains his list of all the cards he has tested on his website.

The Waveshare PCIe-Packet-Switch-4P currently sells in China for around $23. Unfortunately, it’s not available yet through the Waveshare English Store; however, we’re hoping it will eventually be made available for eager Raspberry Pi fans across the globe.


Aizaz khan
Aizaz khan
Aizaz was the first person to get a byline on his blog on technology from his home in Bannu in 2017. Then, he went on to a career in breaking things professionally at my electric sparks which is where he eventually took over the kit as a hardware editor. Today, as the senior editor of hardware for my electric sparks, he spends time reporting about the most recent developments in the hardware industry and technology. If he's not reporting on hardware or electronics, you'll see him trying to be as remote from the world of technology as possible through camping in the wild.


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