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Pi-like RK3568 SBC grows SATA out of its USB ports

Jul 19, 2021 — by Eric Brown 2,036 views

Radxa unveiled a $35-and-up “Rock 3 Model A” SBC that runs Linux on a 2.0GHz, quad -A55 Rockchip RK3568 and offers up to 8GB RAM, GbE with PoE, M.2 M- and E-key, and SATA via USB 3.0.

Radxa has begun sampling a new community backed SBC built around the NPU-equipped Rockchip RK3568 in a collaboration with Rockchip’s Toybrick division. The open-spec Rock 3 Model A (or Rock 3A) will launch in late August at $35 (2GB LPDDR4), $55 (4GB), and $75 (8GB).

The Rock 3 Model A is billed as “basically a little brother of” the RK3399-based Rock Pi 4 and shares the same Raspberry Pi style dimensions, layout, and 40-pin GPIO. This is the first compact, low-priced SBC built around the RK3568, the slightly higher end sibling to the similarly quad-core, Cortex-A55 based RK3566.

Rock 3 Model A (left) and Rockchip RK3568 block diagram
(click images to enlarge)

The RK3568 has appeared on Firefly’s $122 and up Station P2 mini-PC and will soon arrive on Firefly’s Core-3568J AI Core Board module, which will be available in a dev kit. Geniatech provides bth RK3568 and RK3566 Development Boards, which are not publicly priced. The RK3566, meanwhile, has appeared on Firefly’s $89 and up ROC-RK3566-PC SBC, and Pine64 is prepping an unpriced Quartz64 Model A development board and smaller Quartz64 Model B.


Like Rockchip’s RK3566, the RK3568 is equipped with 4x Cortex-A55 cores, which can achieve a 2.0GHz clock rate compared to 1.8GHz on the RK3566. Both SoCs provide a Mali-G52 EE GPU and a 0.8-TOPS NPU.

The major difference is with I/O. The RK3568 supports triple displays, dual GbE, PCIe 3.0 x2, and PCIe 2.1 whereas the RK3566 is limited to dual independent displays, a single GbE port, and PCIe 2.1. The RK3568 also provides 3x CAN FD and 8x (vs. 2x) SAR ADC links.

The Rock 3 Model A exploits the RK3568’s ability to multiplex SERDES lanes to enable SATA support on the dual USB 3.0 ports (OTG and host) via a SATA breakout cable. As Tom’s Hardware notes, the multiplexed SATA “technically breaks the USB spec, which says that other protocols can’t be passed over any USB port other than Type-C.” It remains to be seen whether proper power safeguards are provided “so that SATA peripherals aren’t introduced to USB 3.1’s full power output unexpectedly.”

Rock 3 Model A front view (with Intel AX210 WiFi 6 module) and rear view
(click images to enlarge)

The other improvement over the faster Rock Pi 4 is the addition of an M.2 E-key slot (PCIe 2.0 x1/SDIO/UART) with WiFi 6 (802.11ax) support. Like the Rock Pi 4, the Rock 3A has an M.2 M-key slot with PCIe 3.0 x2 for NVMe storage.

It appears you could have M.2 NVMe storage, which does not use SATA, along with both USB 3.0 ports configured for SATA. As noted in the CNXSoft post that alerted us to the Rock 3A, the lack of a mounting screw for the M.2 M-key slot suggests it uses the same approach as the Rock Pi 4, which supplies an optional NVMe module via an expansion board.

The 2GB to 8GB LPDDR4 is listed with 3200MT/s throughput, with controller frequency up to 1560MHz. The Rock 3 Model A will ship with empty eMMC and microSD slots. The SBC also provides a GbE port with PoE support and MIPI-DSI and -CSI connectors.

Four USB ports are available overall: the USB 3.0 OTG and host ports plus 2x USB 2.0 host ports. The 40-pin GPIO is said to be “mostly” compatible with Rock Pi 4 add-ons. Although not listed in the specs, there also appear to be an HDMI 2.0 port (the RK3568 supports up to 4Kp60), as well as an audio jack and an RTC with battery connector.

A USB Type-C port appears to power the board at 5V. Radxa notes the availability of QC/PD power support “with a new generation QC/PD protocol IC.” Toybrick will provide a Debian 10 image, and comments at the end of the announcement note RK3568 support in Manjaro Linux and Slackware.

Other recent Radxa boards include the Rock Pi 4 Plus variant of the Rock Pi 4, which uses the faster 2GHz OP1 version of the RK3399 and adds 16GB or 32GB eMMC. There is also a Raspberry Pi Zero-like Radxa Zero that runs on Amlogic’s quad -A53 S905Y2. Earlier Radxa SBCs can be found in our Jan. 2021 catalog of 150 Linux hacker boards.

Further information

The Rock 3 Model A is sampling in small quantities for select Radxa developers. In late August, there will be greater availability at $35 (2GB RAM), $55 (4GB), and $75 (8GB). More information may be found in Radxa’s announcement and more will eventually be posted on the Radxa wiki.


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