Testing and comparing small-board computers

RPi3B

The third generation of the small computer was released in February 2016 in the form of the RPi3B (Figure 1). The form factor has remained the same and the Foundation was careful to maintain downward compatibility that extends back even to the RPi1. Their philosophy of cautious advancement combined with retaining board layouts has made many friends for the project. Even so, a good number of users now consider 2GB of working memory and a native Gigabit Ethernet adapter tantamount to basic equipment and therefore something every SBC should offer. The Foundation does not let such thinking affect its decision making, in part because adapting features along these lines would result in a higher price.

Figure 1: The RPi3B boasts a 64-bit CPU with integrated wireless and Bluetooth.

As a result, only the CPU and connectivity were improved for the latest version. The SoC was upgraded to a Broadcom BCM2837, which has a 64 bit basis unlike its predecessor the BCM2836. The processor is a quad-core ARM Cortex-A53 with a 1.2GHz clock speed. It works faster than its predecessor and can implement the ARMv8 A64 instruction set. Theoretically, the new CPU runs approximately 10 times faster than the BCM2836 from the first generation.

The RPi3 also acquired 802.11b/g/n WiFi and Bluetooth 4.1 low energy (LE) functionalities provided by the Broadcom BCM43438 module. However, users who had hoped for 4K and H.265 video decoding with the integrated GPU have met with disappointment. The on-board dual-core video core IV only supports OpenGL for embedded systems (GLES) 1.1/2.0 and 1080p FullHD with 30 frames per second (fps).

Previous Rasp Pi models have been able to handle moderate overclocking through the raspi-config tool. The new version of the tool can no longer be used in this way because the CPU generates higher temperatures that can reach up to 160F (70C). Overclocking under these circumstances could have fatal consequences. During testing, the candidate machines were outfitted with small heat sinks.

Odroid-C2

Hardkernel is a South Korean manufacturer that has created some serious competition for the RPi2 in the form of its Odroid-C1+. Costing $3 less than the Rasp Pi, the $32 C1+ has a better CPU and a Gigabit Ethernet interface. It also offers an SD card slot plus a pluggable eMMC flash memory module, a component that works significantly faster than SD cards.

As a result, it should not come as a surprise that Hardkernel took a step right up to the level of the RPi3 when it brought out the Odroid-C2 (Figure 2). The name Odroid is derived from Open Droid and was created to serve notice that both Linux and Android run on the board.

Figure 2: Compared with the RPi3, the Odroid-C2 offers a faster CPU, more RAM, and Gigabit Ethernet. A removable heat sink sits over the white outline in the middle of the board.

The C2 costs $40 on the Hardkernel website [4] and £44 or EUR50 if purchased in Europe, so the two computers compete pretty much at the same price point. The SoC for the C2 is the Cortex-A53, also found in the RPi3. However, the AMLogic s905 has a clock speed of 2GHz, so it's 800MHz faster than the clock speed for the Rasp Pi. The main memory has been doubled for the Odroid to 2GB, and it has Gigabit Ethernet. The SoC includes an integrated Mali-450 GPU, which generally supports 4K video. It should also handle H.265 with 4K/60fps as well as H.264 with 30fps.

Like its predecessor, the C2 also offers placement for an eMMC module. An 8GB eMMC module for Linux or Android costs $18 (£19, EUR24). A class 10 SanDisk SD card offering the same amount of memory costs about $12 (£8, EUR14). The advantage of using eMMC memory is that the SD card slot does not then need to be used. In contrast to the RPi3, the C2 has no integrated WiFi or Bluetooth, although you can add these functions if desired via the USB connections.

The Odroid-C2 board has identical construction, size, placement, and even holes for fastening as the Rasp Pi. Even so, it is easy to distinguish between the two boards. A large, removable heat sink for discharging heat occupies a prominent place on the C2 (Figure 3). Just for fun, I tried fitting an Odroid-C2 into two different Rasp Pi covers and found that one actually fit.

Figure 3: The Odroid-C2 sporting its removable heat sink.