In this article by Olliver M. Schinagl, author of Getting Started with Cubieboard, we will overview various development boards and compare a few popular ones to help you choose a board tailored to your requirements. In the last few years, ARM-based Systems on Chips (SoCs) have become immensely popular. Compared to the regular x86 Intel-based or AMD-based CPUs, they are much more energy efficient and still performs adequately. They also incorporate a lot of peripherals, such as a Graphics Processor Unit (GPU), a Video Accelerator (VPU), an audio controller, various storage controllers, and various buses (I2C and SPI), to name a few. This immensely reduces the required components on a board. With the reduction in the required components, there are a few obvious advantages, such as reduction in the cost and, consequentially, a much easier design of boards. Thus, many companies with electronic engineers are able to design and manufacture these boards cheaply.

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So, there are many boards; does that mean there are also many SoCs? Quite a few actually, but to keep the following list short, only the most popular ones are listed:

• Allwinner’s A-series
• Broadcom’s BCM-series
• Freescale’s i.MX-series
• MediaTek’s MT-series
• Rockchip’s RK-series
• Samsung’s Exynos-series
• NVIDIA’s Tegra-series
• Texas Instruments’ AM-series and OMAP-series
• Qualcomm’s APQ-series and MSM-series

While many of the potential chips are interesting, Allwinner’s A-series of SoCs will be the focus of this book. Due to their low price and decent availability, quite a few companies design development boards around these chips and sell them at a low cost. Additionally, the A-series is, presently, the most open source friendly series of chips available. There is a fully open source bootloader, and nearly all the hardware is supported by open source drivers. Among the A-series of chips, there are a few choices. The following is the list of the most common and most interesting devices:

• A10: This is the first chip of the A-series and the best supported one, as it has been around for long. It is able to communicate with the outside world over I2C, SPI, MMC, NAND, digital and analog video out, analog audio out, SPDIF, I2S, Ethernet MAC, USB, SATA, and HDMI. This chip initially targeted everything, such as phones, tablets, set-top boxes, and mini PC sticks. For its GPU, it features the MALI-400.
• A10S: This chip followed the A10; it focused mainly on the PC stick market and left out several parts, such as SATA and analog video in/out, and it has no LCD interface. These parts were left out to reduce the cost of the chip, making it interesting for cheap TV sticks.
• A13: This chip was introduced more or less simultaneously with the A10S for primary use in tablets. It lacked SATA, Ethernet MAC, and also HDMI, which reduced the chip’s cost even more.
• A20: This chip was introduced way after the others and hence it was pin-compatible to the A10 intended to replace it. As the name hints, the A20 is a dual-core variant of the A10. The ARM cores are slightly different; Cortex-A7 has been used in the A10 instead of Cortex-A8.
• A23: This chip was introduced after the A31 and A31S and is reasonably similar to the A31 in its design. It features a dual-core Cortex-A7 design and is intended to replace the A13. It is mainly intended to be used in tablets.
• A31: This chip features four Cortex-A7 cores and generally has all the connections that the A10 has. It is, however, not popular within the community because it features a PowerVR GPU that, until now, has seen no community support at all. Additionally, there are no development boards commonly available for this chip.
• A31S: This chip was released slightly after the A31 to solve some issues with the A31. There are no common development boards available.

Choosing the right development board

Allwinner’s A-series of SoCs was produced and sold so cheaply that many companies used these chips in their products, such as tablets, set-top boxes, and eventually, development boards. Before the availability of development boards, people worked on and with tablets and set-top boxes. The most common and popular boards are from Cubietech and Olimex, in part because both companies handed out development boards to community developers for free.

Olimex

Olimex has released a fair amount of different development boards and peripherals. A lot of its boards are open source hardware with schematics and layout files available, and Olimex is also very open source friendly. You can see the Olimex board in the following image:

Olimex offers the A10-OLinuXino-LIME, an A10-based micro board that is marketed to compete with the famous Raspberry Pi price-wise. Due to its small size, it uses less standard, 1.27 mm pitch headers for the pins, but it has nearly all of these pins exposed for use. You can see the A10-OLinuXino-LIME board in the following image:

The Olimex OLinuXino series of boards is available in the A10, A13, and A20 flavors and has more standard, 2.54 mm pitch headers that are compatible with the old IDE and serial connectors. Olimex has various sensors, displays, and other peripherals that are also compatible with these headers.

Cubietech

Cubietech was formed by previous Allwinner employees and was one of the first development boards available using the Allwinner SoC. While it is not open source hardware, it does offer the schematics for download. Cubietech released three boards: the Cubieboard1, the Cubieboard2, and the Cubieboard3—also known as the Cubietruck. Interfacing with these boards can be quite tricky, as they use 2 mm pitch headers that might be hard to find in Europe or America. You can see the Cubietech board in the following image:

Cubieboard1 and Cubieboard2 use identical boards; the only difference is that A20 is used instead of A10 in Cubieboard2. These boards only have a subset of the pins exposed. You can see the Cubietruck board in the following image:

Cubietruck is quite different but a well-designed A20 board. It features everything that the previous boards offer, along with Gigabit Ethernet, VGA, Bluetooth, Wi-Fi, and an optical audio out. This does come at the cost that there are fewer pins to keep the size reasonably small. Compared to Raspberry Pi or LIME, it is almost double the size.

Lemaker

Lemaker made a smart design choice when releasing its Banana Pi board. It is an Allwinner A20-based board but uses the same board size and connector placement as Raspberry Pi and hence the name Banana Pi. Because of this, many of those Raspberry Pi cases could fit the Banana Pi and even shields will fit. Software-wise, it is quite different and does not work when using Raspberry Pi image files. Nevertheless, it features composite video out, stereo audio out, HDMI out Gigabit Ethernet, two USB ports, one USB OtG port, CSI out and LVDS out, and a handful of pins. Also available are a LiPo battery connector and a SATA connector and two buttons, but those might not be accessible on a lot of standard cases. See the following image for the topside of the Banana Pi:

Itead and Olimex

Itead and Olimex both offer an interesting board, which is worth mentioning separately. The Iteaduino Plus and the Olimex A20-SoM are quite interesting concepts; the computing module, which is a board with the SoC, memory, and flash, which are plugin modules, and a separated baseboard. Both of them sell a very complete baseboard as open source hardware, but anybody can design their own baseboard and buy the computing module. You can see the following board by Itead:

Refer to the following board by Olimex:

Additional hardware

While a development board is a key ingredient, there are several other items that are also required. A power supply, for example, is not always supplied and does have some considerations. Also, additional hardware is required for the initial communication and to debug.

Summary

In this article, you looked at the additional hardware and a few extra peripherals that will help you understand the stuff you require for your projects.

Resources for Article:

Further resources on this subject:

• Home Security by BeagleBone [article]
• Mobile Devices [article]
• Making the Unit Very Mobile – Controlling the Movement of a Robot with Legs [article]