Maker Mehdi has shown off an initial prototype of a carrier board designed to turn a Raspberry Pi Compute Module 4 into a low-cost, high-performance network attached storage (NAS) device — and has released all the design files for anyone to build their own.
Released late last year, the Raspberry Pi Compute Module 4 brings the same technology as powers the popular Raspberry Pi 4 Model B single-board computer (SBC) family and puts it on a system-on-module (SOM). Available at a low cost and with surprising compute performance plus a user-accessible PCI Express Gen. 2 lane, it's no surprise to find a range of projects built around the module — including Mehdi's NAS carrier.
"This Compute Module 4 carrier board design exposes a subset of the CM4's interfaces, including its single PCIe [Gen. 2] lane to accept an external SATA controller card," Mehdi writes of the project. "The board was intentionally kept simple to limit mistakes as this is my first ever attempt at designing a PCB and I have no background in electronics, so all the power management is left to external power supplies and buck converters."
Based on the official Raspberry Pi Compute Module 4 IO board, designs for which were published at launch, the carrier board accepts any model of Raspberry Pi Compute Module 4 bar the eMMC-free Lite range and offers a PCI Express Gen. 2 slot for a SATA controller, an Ethernet port, a USB Type-A port which is jumper-switchable between host and device modes, full-size HDMI video output, an I2C header, single-wire temperature sensor, nine user-accessible general-purpose input/output (GPIO) pins, and a fan controller plus a power rail for the hard drives.
Having produced a prototype, Mehdi has confirmed that the core functionality works fine — though there is still some testing to do. "Once I'm done with testing and configuration, if I don't find issues, I will probably stop putting time on this project (unless there is demand)," they write. "Still, there would be a few enhancements the project could benefit from and any contribution to the project is more than welcome!"
Mehdi isn't the only one working on a Compute Module-powered NAS board, either: Late last month Wiretrustee published details of a compact four-bay SATA NAS carrier board of its own, using an on-board SATA controller to do away with the need for an external PCIe SATA card.
The design files for Mehdi's board are available on the project's GitHub repository under an unspecified license; there are also images of a work-in-progress 3D-printed case to hold both the board and the hard drives with active cooling.