Today, many manufacturers offer more or less professional single-board computers. Most work with ARM Cortex CPUs, some also with Intel or other processors. Two to four CPU cores and clock rates of up to or even over 2 GHz are not uncommon. The processor cores are integrated into a system-on-a-chip (SoC), which also contains most of the computer's other functions. The computers generally use a Linux distribution as their operating system. This is in line with the open source strategy and makes development work easier. A wide range of software is also available. With a few exceptions, other components of the compact computers include a powerful graphics chip (GPU) and RAM of between 512 MB and 4 GB. In addition to performance, the interfaces vary greatly from model to model.

There is now a whole range of compact embedded computers that are suitable for professional use due to their high performance. Not all boards are designed directly for use in harsh industrial environments. However, appropriate adaptations such as housing or improved cooling make it possible to use these single-board computers for control tasks, for example. We present some of the most important systems here.

The classic: the raspberry

The Raspberry Pi 3 Model B+ is the latest model of the popular mini computer. © RS Components

The best-known and probably most widespread of the single-board computers is the Raspberry Pi, which was initially developed in England for learning and educational purposes and launched on the market in 2012.

The latest Pi 3 B+ model of the open source board was released in March 2018. The SoC comes from Broadcom and contains a 64-bit ARM Cortex-A53 processor with four processor cores clocked at 1.4 GHz. The GPU also comes from Broadcom and has a composite and HDMI connection. The selection of possible operating systems is extensive: in addition to the Debian-based Raspbian and other Linux distributions, a Windws 10 version is also available.

In contrast to the previous models, Android has also been running on the Raspberry Pi since the Model 3 B. The Pi 3 B+ has four USB 2.0 interfaces, as well as Bluetooth and now also dual-band Gigabit Ethernet. The GPIO general purpose interface offers 26 pins for free programming. A microSD card reader is integrated for fixed memory. An audio output via HMDI or 3.5 mm jack as well as CSI for connecting a camera, DSI for the monitor and ^I2Cround off the range of interfaces.

Everything except windfalls

The Banana Pi, which was developed in China, is based on the Raspberry Pi, but is not related to it. The core of this open source computer is an Allwinner SoC with an ARM Cortex CPU. Versions with two, four and eight processor cores are available. With 2 GB DDR3 SDRAM, the M3 and M64 models - the latter with a 64-bit CPU - are generously equipped with memory. The newer versions of the Banana Pi are also equipped with a microSD slot. The M2+, M3 and M64 models each have two USB 2.0 hosts and 40-pin GPIO as well as Bluetooth. HDI as well as DSI for M3 and M64 are available as video interfaces. M2+ and M3 also have a CSI camera connection. WLAN and GB-Ethernet are common to all models. The board dimensions of the Banana Pi are similar to those of the Raspberry Pi models.

Integrated development environment

Arduino offers various boards. Here is an Arduino Leonardo with microUSB connection ATmega32u4 controller. © Pixabay

For years, Arduino has been offering a range of different, predominantly simpler, single-board boards with CPUs or microcontrollers with 8 or 32 bits in open source format. The most common are controllers from Atmel, while the more powerful boards are equipped with 32-bit ARM Cotex-M processors. They have digital and analog inputs and outputs. The great advantage of the Arduino platform is that it includes an integrated development environment. This is free and available for Linux, Windows and Mac OS. The integrated compiler is gcc, so programming is based on C or C++. A graphical operating system is not provided.