Open-spec single board computers (SBCs) have become incredibly popular over the past decade. Community-backed groups like Raspberry Pi, Orange Pi, Odroid and Khadas offer a variety of low-cost, small form factor products sought after by both makers and professional engineers alike.
Over the past several years, the number of available open-spec SBCs has continued to grow. The definition of “open spec” can vary. For this article we’re looking at boards that fulfill most of the open source criteria. This ranges from community resources to strong open source software support to open schematics and open licensing. The nature of open-spec SBCs is such that most products tend to be smaller boards and feature very low costs in comparison to commercial non-open SBCs. To be clear, open-spec SBCs are very well suited for maker and DIY projects and even for professional embedded system developers to use as prototype boards. But they are very different than an SBC supplied by a commercial vendor that can ensure long lifecycle support. A commercial SBC vendor will take on the burden of parts obsolescence for customers in ways that open spec SBC suppliers really aren’t set up to do.
Another common attribute of open-spec SBCs is that most of them run Linux or Android. In no surprise therefore, that Circuit Cellar’s sister website LinuxGizmos.com publishes a comprehensive catalog of open-spec SBCs at least once each year. Its last updated catalog posted in January included 136 open-spec Linux SBCs. The catalog confines its scope to SBCs that cost under $200. The product gallery on the next three pages provides a representative set of these SBCs, including the most popular ones from LinuxGizmos.com’s coverage. Surveys of LinuxGizmos’s readers show that year after year Raspberry Pi SBCs are the most popular open-spec SBCs. Because of that, we eased our one 1-product-per-company rule in this article and included two Raspberry Pi SBCs. Also, open-spec SBC vendors don’t ever seem to provide traditional datasheets for their products. So, the links provided in the product gallery are to other types of documentation that lists the specs of these SBCs.
An example project that made use of an open-spec Raspberry Pi SBC is a system designed to monitor all the refrigeration units in a commercial kitchen simultaneously (Figure 1). The system uses Microchip PIC MCU-based monitoring units and is controlled by a Raspberry Pi 3B SBC.
PUBLISHED IN CIRCUIT CELLAR MAGAZINE • AUGUST 2020 #361 – Get a PDF of the issue
SBC Sports Coral SOM and
Three USB Ports
The Tinker Edge T SBC from Asus runs Linux on the same Coral SOM module found on Google’s Coral Dev Board. This variant of Google’s Coral Dev Board has a similar, Raspberry Pi -like layout and uses the same Coral SOM, which combines a quad-core NXP i.MX8M with Google’s Edge TPU AI chip.
• Coral SOM
• 1GB LPDDR4 RAM, 8GB eMMC flash
• 802.11 b/g/n/ac 2×2 MIMO and Bluetooth 4.1 BLE
• Gbit Ethernet port
• HDMI port, MIPI-DSI, 2x MIPI-CSI2
• 2x USB 3.2 Gen1 host ports
• USB 3.2 Gen1 Type C OTG port
• Operating temperature: 0°C to 50°C
• Dimensions: 85mm × 56 mm
Tinker Edge T datasheet
BeagleBone AI Board Features Four EVE ML Cores
The BeagleBoard.org Foundation's BeagleBone AI is the heir to the BeagleBone Black. The BeagleBone AI’s 1.5GHz, dual-core Cortex-A15 Texas Instruments (TI) Sitara AM5729 is complemented by several coprocessors led by the SoC’s four embedded-vision-engine (EVE) neural processing cores with AI capabilities.
• TI Sitara AM5729 SoC
• SoC includes several co-processors, including 4xEVEs
• BeagleBone Black mechanical and header compatibility
• 1GB RAM and 16GB on-board eMMC flash with high-speed interface
• USB type-C for power and superspeed dual-role controller;
USB type-A host
• Gbit Ethernet
• 2.4/5GHz Wi-Fi; Bluetooth
BeagleBone AI datasheet
BTiny SBC Has Quad-Core Allwinner H3 and GbE
FriendlyElec's ZeroPi SBC is a headless, open-spec SBC that combines the quad-core, Cortex-A7 Allwinner H3 of its NanoPi Neo with the Gbit Ethernet port of its Allwinner H5-based NanoPi Neo2. The ZeroPi shares the same 40mm × 40mm footprint, USB 2.0 host, micro-USB, and debug header of these earlier models, and it offers the -20°C to 70°C range of the Neo.
• Allwinner H3 (4x Cortex-A7 at 1.2GHz)
• 512MB DDR3 SDRAM
• MicroSD slot for up to 128GB
• 10/100/1000Mbps Ethernet port
• USB 2.0 host port;
Micro-USB 2.0 OTG port
• 5V at 2A via micro-USB
• Operating temperature: 20°C to 70°C
• Dimensions: 40mm × 40mm
SBC Serves Up Hexa-Core Amlogic S922X
The Odroid-N2 SBC from Hardkernel features a Cortex-A73 and -A53 based Amlogic S922X SoC plus 2-4GB DDR4, 4x USB 3.0, HDMI 2.1, an audio DAC and a 40-pin header. The S922X SoC has 4x Cortex-A73 cores and 2x -A53 cores that clock to 1.9GHz. The N2 moves up to a Mali-G52 GPU with 6x 846MHz execution engines, which the Odroid project benchmarks as 10% faster.
• Amlogic S922X processor
• 2GB or 4GB DDR4 32-bit RAM;
8MB SPI flash
• eMMC socket; MicroSD slot
• Optional USB WiFi adapter
• Gbit Ethernet port
• HDMI 2.1 port
• 4x USB 3.0, 1x Micro-USB 2.0
• Dimensions: 90mm × 90mm
SBC Provides NPU-Equipped Amlogic A311D
The VIM3 SBC is the latest addition to Shenzhen Wesion’s Khadas project. It has an Amlogic A311D SoC. On the SoC x4 Cortex A73 performance-cores (2.2GHz) and x2 Cortex A53 efficiency-cores (1.8GHz) are merged into a hexa-core configuration, and fabricated with a 12nm process to maximize performance, thermal and electrical efficiency.
• MicroSD slot; NVMe via M.2
• Gbit Ethernet;
Wi-Fi and Bluetooth 5.0
• HDMI 2.1; MIPI-DSI; MIPI-CSI
• Dual independent displays
• Touch-panel support
• 2x USB 3.0 host ports;
1x USB 2.0 Type-C
• Dimensions: 82mm × 58mm
Rockchip RK3399 SoC Rides Orange Pi 4 SBC
The Orange Pi 4 SBC from Shenzhen Xunlong is similar in layout and features to the Allwinner H6-based Orange Pi 3, which preceded it by only about six months, but advances to a more powerful, hexa-core Rockchip RK3399 backed up with 4GB DDR4. The standard Orange Pi 4 also offers a USB 3.0 host port.
• Rockchip RK3399 processor
• 4GB LPDDR4 RAM; 16GB eMMC flash
• MicroSD slot
• HDMI 2.0a; DisplayPort 1.2
• 2x LCD connectors (MIPI-DSI);
• Gbit Ethernet; Wi-Fi; Bluetooth 5.0
• USB 3.0 Type-C; USB 3.0 host port
• 2x USB 2.0 host ports
• Dimensions: 91mm × 56 mm
Orange Pi 4 datasheet
Raspberry Pi 3B+ SBC Has
Wi-Fi and GbE with PoE
Raspberry Pi 3B+ SBC from the Raspberry Pi Foundation is the final revision of its third-generation SBC. Raspberry Pi 3 Model B+ provides a 1.4GHz 64-bit quad-core A53 processor, dual-band wireless LAN, Bluetooth 4.2/BLE, faster Ethernet and Power-over-Ethernet support (with separate PoE HAT).
• 1.4GHz Broadcom BCM2837B0 Cortex-A53 SoC
• 1GB LPDDR2 SDRAM
• Wi-Fi, Bluetooth 4.2, BLE
• Gbit Ethernet over USB 2.0
• Extended 40-pin GPIO header
• Full-size HDMI
• 4 USB 2.0 ports
• CSI camera port for RPi camera
• PoE support (requires separate PoE HAT)
Raspberry Pi 3B+ datasheet
Latest Raspberry Pi 4 Features 8GB RAM
The latest version of the Raspberry Pi 4 from the Raspberry Pi Foundation provides 8GB of DDR4 DRAM. Along with the release, the organization also released Raspberry Pi OS with a 64-bit architecture that can fully exploit the 8GB RAM.
• 1.5GHz Broadcom BCM2837B0 BCM2711 Cortex-A72
• 2GB to 8GB LPDDR4-3200 SDRAM
• Wi-Fi, Bluetooth 5.0, BLE
• Gbit Ethernet
• 2x USB 3.0; 2x USB 2.0
• 2x micro-HDMI; MIPI DSI; MIPI CSI
• PoE support (requires separate PoE HAT)
• Operating temperature: 0 to 50°C
Raspberry Pi 4 datasheet
SBC Boasts AI-Enabled Rockchip RK3399Pro SoC
The Rock Pi N10 SBC from Radxa is an AI-enabled Rockchip RK3399Pro SoC delivered via Vamrs’ SMARC form-factor VMARC RK3399Pro SoM compute module. The RK3399Pro is essentially a hexa-core RK3399 that adds an up to 3-TOPS NPU. The Rock Pi N10 is a sandwich-style 100mm × 100mm board.
• Rockchip RK3399Pro processor on VMARC SoM
• 4GB to 8GB LPDDR3
• 16GB to 64GB eMMC 5.1
• MicroSD slot; M.2 socket
• Gbit Ethernet port with PoE (requires PoE HAT)
• HDMI 2.0a; MIPI-DSI; MIPI-CSI;
• USB 3.0 OTG; USB Type-C;
2x USB 2.0 host ports
• Dimensions: 100mm × 100mm
Rock Pi N10 datasheet
Jeff served as Editor-in-Chief for both LinuxGizmos.com and its sister publication, Circuit Cellar magazine 6/2017—3/2022. In nearly three decades of covering the embedded electronics and computing industry, Jeff has also held senior editorial positions at EE Times, Computer Design, Electronic Design, Embedded Systems Development, and COTS Journal. His knowledge spans a broad range of electronics and computing topics, including CPUs, MCUs, memory, storage, graphics, power supplies, software development, and real-time OSes.