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RPi CM4 powered PiTray opens at $14.50 as more carriers prep for launch

Feb 3, 2021 — by Eric Brown 13,007 views

Sourcekit has launched a $14.50 “PiTray mini” carrier for the Raspberry Pi CM4. Two more CM4 carriers will soon appear on Crowd Supply: Wiretrustee’s 4-port “SATA Board” and an M.2-equipped “Piunora.”

The Raspberry Pi Compute Module 4 launched with a large, $35 IO Board, but that has not stopped third parties from spinning their own RPi CM4 carrier boards. Fuzhou Sourcekit is staking out the low-end of the market with a simple, Raspberry Pi sized Sourcekit PiTray mini board. The cluster-focused PiTray mini is on pre-order at DFRobot for $14.50, with shipments due at the end of the month.

Sourcekit PiTray mini (left) and Wiretrustee’s SATA Board for Raspberry Pi CM4
(click images to enlarge)

Last week, Wiretrustee revealed a SATA Board for Raspberry Pi CM4 that will soon appear on Crowd Supply. The unpriced SATA Board boasts 4x SATA 2.0 slots (see farther below).

Timonsku’s Arduino form-factor Piunora, which was revealed in early December, now has a Crowd Supply page for notification sign-up. No price has been announced for the Piunora, which will likely be a bit more due to the addition of two features not found on the PiTray or SATA Board: a MIPI-CSI camera connector and an M.2 B-key slot to extend the CM4’s PCIe 2.0 interface. Czech maker, meanwhile, copied an earlier and much simpler Timonsku CM4 carrier design for a “Minimal carrier board for Compute Module 4” project (see farther below).


Other CM4 carriers and CM4 background

The PiTray, SATA Board, and Piunora follow other CM4 carriers including the $130 Gumstix Raspberry Pi CM4 Development Board, which is on pre-order along with other Gumstix CM4 carriers for robotics, Pixhawk drones, and PoE cameras. Meanwhile, StereoPi’s camera focused, open-spec StereoPi v2 has yet to launch on Crowd Supply.

The Mini-ITX form-factor Over:Board is still available for another day and a half for 90 UK Pounds on Indiegogo, with shipments due in September. The project has achieved almost 70 percent of its $137K flexible goal.


The unpriced Turing Pi 2 CM4 cluster board has yet to launch. Seeed is still prepping an unnamed CM4 carrier, and you can sign up for discounted design and manufacturing fees on the creation of your own CM4 carrier on the Seeed Fusion PCB Assembly Service.

The Raspberry Pi CM4 switched from the SODIMM connector of the RPi CM3+ and CM3 to dual (low speed and high speed) 100-pin connectors. This enables a smaller 55 x 40 x 4.7mm footprint compared to the earlier 67.6 x 31mm but prohibits backward compatibility to earlier carriers.

The Linux-powered, $25 to $90 Raspberry Pi CM4 module has the same Broadcom BCM2711 SoC with 4x 1.5GHz Cortex-A72 cores that is used on the Raspberry Pi 4. The module ships with 2GB to 8GB LPDDR4-3200 RAM and 0GB to 32GB eMMC. There is a GbE controller with PoE support, optional 802.11ac with BT 5.0, and new support for dual 4K HDMI ports and PCIe 2.0. Other features include 2x and 4x MIPI-DSI and -CSI interfaces.

Sourcekit PiTray

Fuzhou Sourcekit’s PiTray mini may well be the first third-party CM4 carrier to reach market. It is also the most affordable.

Although the PiTray mini can load only a single Raspberry Pi CM4, it is designed primarily for clustering projects with multiple PiTrays connected via GbE. The product name suggests that a maxi version that supports clustering of multiple modules could be in the works.

Advantages over the Raspberry Pi 4 Model B include the ability to use faster and more reliable eMMC storage and to save on power consumption by using a non WiFi/BT CM4 variant. The PiTray mini supports all variants of the CM4.

Sourcekit PiTray mini detail view (left) and clockwise from top: 4-board PiTray cluster, PiTray mini, and RPi 4 SBC
(click images to enlarge)

The $14.50 carrier has the same 85 x 56mm footprint as the Raspberry Pi SBCs. The board supplies the standard 40-pin GPIO and the usual M2.5 screw holes for securing HATs.

The PiTray mini has a much more limited feature set than the RPi 4 SBC, with single GbE, HDMI 2.0, and USB 2.0 ports. A USB Type-C port supports power input and “programming eMMC variants of CM4,” says Sourcekit.

The PiTray mini is further equipped with a microSD slot, a boot mode switch, a run/reset button, and 2x LEDs. As noted by the Tom’s Hardware report that alerted us to the product, the PiTray mini appears to lack a breakout for one of the CM4’s coolest new features: PCIe. There is no indication that this is an open hardware design, although there is a wiki and a GitHub discussion page where the maintainer has posted some images of a four-board PiTray mini cluster.

SATA Board for Raspberry Pi CM4

Wirestrustee recently revealed on a SATA Board for Raspberry Pi CM4 that it plans to launch on Crowd Supply for an undisclosed price. This NAS-oriented board provides a Marvell 88SE9215 controller to enable 4x powered SATA ports with up to 220MB/s throughput.

SATA Board for Raspberry Pi CM4, front and back
(click images to enlarge)

The 100 x 100mm board supports any CM4 variant. The board provides a microSD slot, 2x USB 2.0 ports, and single GbE, HDMI 2.0, and USB Type-C ports.

SATA Board for Raspberry Pi CM4 detail views
(click images to enlarge)

Other features include a fan header, real-time clock with battery backup, and a 12V/5A input jack to support up to 3.5-inch HDDs. There is also a separate front-panel LED control board.


The Piunora was revealed on in early December and in mid-January appeared on a Crowd Supply page where you can sign up to be notified about the launch. Like the Gumstix RPi CM4 Dev Board, it provides an M.2 slot.

Piunura with CM4 (left) and rear view
(click images to enlarge)

The open-spec Piunora has an Arduino UNO R3/Adafruit Metro compatible form factor with 3.3v logic. There is no Ethernet port, but you could use a WiFi/BT version of the CM4 or connect it to a PC via the power- and device-enabled USB Type-C port via USB gadget mode, either through a virtual Ethernet connection or as USB mass-storage device. “Then, thanks to Adafruit Blinka (a compatibility layer for CircuitPython on Linux Single Board Computers), you can use Piunora just like any other CircuitPython dev board,” says Timonsku.

The Piunora is further equipped with full-sized HDMI and MIPI-CSI camera connectors plus 6x 10-bit ADC inputs, an LED, and a user button. There is also a USB 2.0 host port and support for on-the-fly switching with the Type-C port. The M.2 B-key socket supports SSDs and other M.2 modules such as Google’s Coral Accelerator.

Minimal carrier board for Compute Module 4

An earlier Timonsku Minimal Raspberry Pi CM 4 Carrier reference design posted on Hackaday under the name Prof. Fartsparkle, was copied and modified for a Minimal carrier board for Compute Module 4 from “Czech maker.” Tindie has a shopping page for the currently out-of-stock board, which sells for $15.

Czech maker’s Minimal carrier board for Compute Module 4 (left) and earlier Minimal Raspberry Pi CM 4 Carrier
(click images to enlarge)

Czech maker, which notes that the carrier is “just a copy of the design from Timon,” adds a 2×7 pin header and a slightly altered shape to ensure easier 3D printing. It is unclear if Czech maker has any plans to build more of the open-spec Minimal boards, which have a few limitations including the single HDMI and USB host ports being too close together. There is also a microSD slot and Type-C port, but no CSI or M.2 connections.

Further information

The Sourcekit PiTray mini is available for $14.50 pre-order at DFRobot, with shipments due later this month. More information may be found on Fuzhou Sourcekit’s wiki page.

Wiretrustee’s SATA Board for Raspberry Pi CM4 will appear on Crowd Supply at an undisclosed price and time.

Timonsku’s Piunora will launch at an undisclosed price on this Crowd Supply page.

(advertise here)

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2 responses to “RPi CM4 powered PiTray opens at $14.50 as more carriers prep for launch”

  1. jayrojones says:

    So uh… Anyone care to explain why there’s no USB 3.0 on ANY of these boards..?

  2. Bleugh says:

    cause the Broadcom IC only supports USB2

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