This $99 Raspberry Pi CM4 Board Can Put Your Idle PC Parts To Good Use
If you're not someone who does a lot of experimenting with single-board computers, when you hear "Raspberry Pi" you probably think of a little circuit board with some chips, ringed in I/O ports. There's another form of Raspberry Pi, though. The Raspberry Pi Compute Modules are functionally identical to their equivalent standard Raspberry Pi products, but with minimal connectivity. That allows them to be much smaller and thinner than the standard Raspberry Pi boards.
Of course, you're probably wondering what the point is if you can't hook anything up to it. The point is that the compute modules include a specialized bus intended for connection to a "carrier board" that provides all the I/O for the Pi's SoC. The Raspberry Pi Compute Module 4 (CM4) is the latest version, and it comes in 32 different variants depending on whether you want on-board Wi-Fi, eMMC storage, and how much memory you need. While earlier Pi Compute Modules used a SO-DIMM form factor, the CM4 uses a pair of 100-pin mezzanine connectors.
Raspberry Pi Trading Ltd—the folks who make these things—already sells its own standard I/O carrier board for the CM4 that includes a pair of HDMI ports, an Ethernet connection, two USB 2.0 ports, a micro-SD slot, a four-pin fan connector, and a pile of miscellaneous other connections. Included in that "other" are a PCIe 2.0 x1 slot (like on the Quartz64) and a connector for Raspberry Pi "hats," which are specialized expansion boards that would normally sit atop the standard Raspberry Pi 4.
Well, Axzez felt like it could do one better and is now taking orders for its own carrier board design, known as the Interceptor. Just like the official model, the Pi CM4 snaps into the mezzanine connectors in the middle, and then the Interceptor provides all of the I/O. In this case you get not-one-but-FOUR Gigabit Ethernet connections, five SATA-III ports, four USB 2.0 ports, four three-pin fan connectors, two HDMI 2.0 connectors, an an RS-485 high-speed serial port.
Unfortunately, the Interceptor misses out on the 40-pin GPIO connector normally found on the Raspberry Pi, but it does include a pair of 40-pin FFC connectors for "future expansion." Axzez hasn't elaborated what sort of expansion that would be, but it's not hard to imagine GPIO being one such option. If this is exactly what you're looking for in a CM4 carrier board, hit up the Axzez site to place an order for the $99 part.