Focus on Low Cost
Whether used for DIY projects or as prototypes for professional designs, open-spec SBCs provide a quality, low-cost solution for embedded computing. Developed by community-backed groups like the Raspberry Pi Foundation and private manufacturers, these boards offer rich computing and connectivity features at affordable prices.
The number of available open-spec single board computers (SBCs) continues to multiply. For our purposes, we loosely define “open spec” as boards ranging from those with community resources to strong open-source software support to open schematics and open licensing. One important characteristic of these SBCs is they tend to be a lot lower in price than traditional commercial boards. That said, readers should be clear-eyed about why these open-spec SBCs are cheaper. Open-spec boards are great for maker projects and prototyping, but they are very different than an SBC supplied by a commercial vendor that can ensure long lifecycle support. Commercial SBC vendors will take on the burden of parts obsolescence for customers in ways that open spec SBC suppliers really aren’t set up to do.
Circuit Cellar’s sister website LinuxGizmos.com publishes a comprehensive catalog of open-spec SBCs each year. Its most recent version, posted in January 2021, included 150 open-spec Linux SBCs [1]. The catalog provides updated summaries of 150 community-backed and predominantly open-spec Linux/Android hacker boards under $200.
The intro piece for LinuxGizmos’ 2021 catalog examined the highlights and trends of the 33 newest boards from 2020 and provided price/performance and feature matrix charts. Because there obviously isn’t space in this Datasheet section to detail even the just the new boards from the catalog, here we’ve decided instead to round-up the lowest priced products among those 33 SBCs. We’ve also included the Raspberry Pi 4B for comparison’s sake even though it wasn’t a 2020 product. That’s because Raspberry Pi is the most popular by far of today’s crop of open-spec SBCs.
An example project using an open-spec Raspberry Pi SBC was written up by regular Circuit Cellar author Devlin Gualtieri is his article “Machine Vision Random Number Generator: Using the Raspberry Pi” [2]. In the article, Dev presents a random number generator project that uses machine vision to acquire true randomness from a physical source (Figure 1). His machine vision physical random number generator is built around the Raspberry Pi, a YoLuke HD Webcam, an LED light source and an LCD connected to the I2C-capable GPIO pins of the Raspberry Pi.
This machine vision physical random number generator is built around the Raspberry Pi, a YoLuke HD Webcam, an LED light source and an LCD connected to the I2C-capable GPIO pins of the Raspberry Pi.
PUBLISHED IN CIRCUIT CELLAR MAGAZINE • SEPTEMBER 2021 #374 – Get a PDF of the issue
Rockchip RK3308 Board Offers 256MB of RAM
Firefly’s ROC-RK3308B-CC Plus SBC succeeds its predecessor, the ROC-RK3308-CC, with a larger form factor of 85.15mm × 60mm board and offers the same RK3308 CPU and memories, but implements them via a new Core Board RK3308B compute module. Additional storage is available via the SBC’s pre-existing microSD slot and USB host and Type-C OTG ports.
• Rockchip RK3308 (4x Cortex-A35 at 1.3GHz)
• 256MB DDR3 RAM
• 128MB NAND flash; 4GB eMMC
• 100Mbit Ethernet (RJ45 interface), PoE Support
• 802.11 b/g/n Wi-Fi; Bluetooth 4.2
• 1x USB 2.0, 1x OTG (Type C)
• 3x I2C, 2x UART, SPI, 3x PWM, I2S, LCD
• 2x ADC, Lineout, SPDIF, In/Out
• Operating temperature:
-20°C to +80°C
• Price: $40
datasheet
Compact SBC runs Linux on RK3328 Processor
FriendlyElec’s NanoPi Neo3 SBC runs Linux on a quad-A53 Rockchip RK3328 with 1GB or 2GB DDR4 and provides USB 3.0, Gbit Ethernet and -20°C to +70°C support. Its form factor is a compact 48mm × 48mm. The 22‑gram SBC’s options include a case with heatsink. Two OS images are available with Linux 5.4 LTS: Ubuntu Core 18.04 and FriendlyWrt, FriendlyElec’s spin of OpenWrt.
• Rockchip RK3328 (4x Cortex-A53 cores at up to 1.5GHz
• Mali-450 MP2 GPU
• 1GB or 2GB DDR4 RAM
• MicroSD slot (bootable)
• Gbit Ethernet with unique MAC
• USB 3.0, 2x USB 2.0, Micro-USB,
26-pin GPIO
• Serial debug header; fan connector
• Operating temperature:
-20°C to +70°C
• Price: $44
datasheet
Open-Spec RK3328 SBC Provides Dual GbE
FriendlyElec’s NanoPi R2S router SBC is an update to its community-backed NanoPi R1S-H3, NanoPi R1S-H5, and earlier NanoPi R1 router boards that similarly targets basic routing and IoT duties. The NanoPi R2S switches from the quad-core Cortex-A7 Allwinner H3 on the R1S-H3 and the quad -A53 Allwinner H5 on the R1S-H5 to tap the quad -A53 Rockchip RK3328.
• Rockchip RK3328 (4x Cortex-A53 cores at up to 1.4GHz
• Mali-450 MP2 GPU
• 1GB DDR4 RAM
• MicroSD slot
• 2x Gbit Ethernet ports at 941Mbps
• USB 2.0 host port, Micro-USB 2.0 power and device port
• Serial debug header; 10x GPIO
• Operating temperature:
0°C to +80°C
• Price: $46
Embedded PC Boasts Four USB 3.2 Gen2 Slots
Hardkernel’s Odroid-C4 SBC is an open-spec Raspberry Pi 4 competitor and lookalike. It integrates Amlogic’s S905X3 SoC. The Odroid-C4 is heir to the similarly open-spec Odroid-C2, which was one of the most popular rivals of the Raspberry Pi 3. Unlike the RPi 4, there’s open eMMC socket and 4x USB 3.0 host ports instead of a mix of USB 3.0 and 2.0.
• Amlogic S905X3 (4x Cortex-A55 at up to 2GHz)
• Mali-G31 GPU at up to 650MHz
• 4GB LPDDR4 RAM (2640 MT/s)
• Empty eMMC socket with optional 8GB to 64GB; MicroSD slot
• Gbit Ethernet port with 2x LEDs
• Optional WiFi USB dongle
• HDMI 2.0 port for up to 4K at 60Hz with audio output
• Audio header with I2S, DC 5V and SPDIF
• 4x USB 3.0 host ports, Micro-USB 2.0 OTG port (no power)
• Serial debug console;
40-pin GPIO header
• Price: $54
datasheet
Tiny Dual GbE Orange Pi is Based on RK3328
The Orange Pi R1 Plus router board from Shenzhen Xunlong is an update to its circa-2017 Orange Pi R1 mini-router SBC. The Orange Pi R1 Plus advances from a 1.2GHz, quad-core, Cortex-A7 Allwinner H2 (and later H2+) to a 1.5GHz, quad -A53 Rockchip RK3328. The dimensions have grown slightly to 57mm × 56mm. The micro-USB OTG port has switched to a USB Type-C port.
• Rockchip RK3328 4x Cortex-A53 at 1.5GHz)
• Arm Mali-450 MP2 GPU
• 1GB DDR4 (dual 512MB); 16MB SPI flash; MicroSD slot
• 2x Gbit Ethernet ports; USB 2.0 host port,
• USB Type-C port for 5V/2A power input and optional cable
• Serial debug interface; Fan interface (5V)
• 13-pin GPIO header with optional expansion board
• 2x LEDs; optional heatsink; 5V power via Type-C or 2-pin header
• Price: $31
datasheet
Orange Pi SBC Serves Up Allwinner H616 SoC
The Orange Pi Zero2 SBC Shenzhen Xunlong sports a quad -A53 Allwinner H616 SoC, up to 1GB RAM, GbE, 802.11ac, BT 5.0, micro-HDMI, USB 2.0 and 26- and 13-pin GPIO headers. The Zero2 has grown to 60mm × 53mm compared to 48mm × 46mm for the Zero, but switches to a much faster quad-core, Cortex-A53 based Allwinner H616 processor compared to the quad-A7 Allwinner H2.
• Allwinner H616 (4x Cortex-A53 at 1.5GHz)
• Mali-TG31 MP2 GPU with OpenGL ES 1.0/2.0/3.2 and OpenCL 2.0
• 512MB or 1GB DDR3 RAM
• 2MB SPI flash; MicroSD slot
• 10/100/1000Mbps Ethernet port
• Dual-band 802.11a/b/g/n/ac Wi-Fi and Bluetooth 5.0
• USB 2.0 host port, 2x USB 2.0
• USB Type-C port with power input
• 13-pin GPIO with 2x USB, IR pin, TV-out, audio and 3x GPIO
• 26-pin GPIO header with I2C, SPI, UART and GPIOs
• Price: $24
datasheet
5MP Camera Dev Kit Embeds Allwinner S3 SoC
Pine64’s PineCube camera dev kit offers a 5MP (Mpixels/s) OmniVision OV5640 based M12 camera with IR night-vision plus audio I/O, Wi-Fi, 10/100 LAN with PoE, USB, 26-pin GPIO and optional battery and display. The 55mm × 51.5mm × 51mm, double-board PineCube runs on an 800MHz, Cortex-A7 based Allwinner S3, a camera-focused SoC.
• Allwinner S3 (1x Cortex-A7 at 800MHz)
• 128MB DDR3 DRAM; 128Mb SPI NOR flash
• MicroSD slot (bootable)
• 10/100Mbps Ethernet port with passive PoE
• 2.4GHz 802.11n/g/b Wi-Fi
• OmniVision 5MP OV5640 camera sensor
• IR LED array for night vision; Photoresistor sensor
• USB 2.0 host port; Micro-USB port for PD; 26-pin GPIO
• Home button; schematics and other docs
• Price: $30
datasheet
Dual LAN RK3328SBC has 40-pin GPIO
Radxa’s Rock Pi E is an SBC with dual LAN ports that runs Linux on a quad-core, Cortex-A53 Rockchip RK3328. The 65mm × 56mm networking board is a big sister to Radxa’s even smaller, quad -A35 RK3308-based Rock Pi S. The Rock Pi E provides both 10/100Mbps and PoE-ready GbE ports instead of 10/100 only. It swaps out a 26-pin GPIO for 40-pin and boosts the USB port to USB 3.0.
• Rockchip RK3328 (4x Cortex-A53 cores at up to 1.5GHz)
• Mali-450 MP2 GPU
• 512MB and 1GB DDR3 RAM
• MicroSD slot for 16GB to 128GB
• Empty EMMC socket for up to 128GB
• Gbit Ethernet port with optional PoE (requires HAT)
• Optional 2.4GHz/5GHz Wi-Fi with Bluetooth 4.2
• USB 3.0 host port; USB Type-C port (5V power input only)
• 40-pin GPIO with USB 2.0, I2C. SPI, I2S, 2x UART, 2x 5V-in, 2x 3.3V-in
• Price: $26
datasheet
Iaspberry Pi 4B Delivers
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
• Price: $55 (4GB)
datasheet
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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.
