Comparison of the SOM modules with the Compute Module 3.

This is why Kontron has extended industrial standards in the starter kit, which uses the same CPU as the Rpi 3 compute module. It has all the interfaces commonly used in industry, such as Ethernet, CANbus, 1-Wire, the RS-485 serial interface for high-speed data transmission over long distances, RS-232 to ensure downward compatibility with older control devices, for example, inputs and outputs for 24 V, analog inputs, reverse polarity protection and greater interference immunity.

Kontron is planning further variants, for example specifically for IoT gateways with a 24 V supply, LAN interface, a security chip and corresponding connectivity. Another version is being developed for controlling displays and touchscreens for web panels or digital signage.

Rpi in comparison with Arm Cortex CPUs

As an alternative to the Rpi Compute Module 3, Kontron also offers two SOM variants and a SMARC module with the comparable family of Arm Cortex-A7 and Cortex-A9 quad-core processors as well as a Qseven module with the Arm Cortex-A7. The comparison in the table shows that the Rpi Compute Module 3 is better than Cortex-A9 quad in four points and better than Cortex-A7 in three points for the requirements of the application described.

The Kontron KBox A-330-RPI is based on the long-term available Raspberry Pi Compute Module CM3+ and can therefore use the huge software pool of the Raspberry Pi community. © Kontron

The combination of processor performance, short time-to-market and a favorable price-performance ratio make Rpi very attractive for the series development of industrial solutions. Ultimately, the choice of processor depends on the individual requirements of an application. The price of the mini-computer is often not the decisive argument: the ease of use of the software is often more important. The widespread operating system Raspian OS based on Linux makes it easy to install software packages. However, embedded Linux is much more complex to install and administer.

According to the Raspberry Foundation, Rpi had been sold around 22 million times by the end of 2018. On the one hand, this is a big plus, but open source is only of limited benefit to industrial users. Although many applications are available license-free, if the source code is adapted, this must also be published under a free license. The same applies if only individual modules from existing applications are used. If you are not dependent on Linux, you can also use Windows IoT Core.

Starter kit for Rpi CM 4 in planning

The Raspberry Foundation launched the Rpi 4 on the market in June. New features include up to 4 GB of RAM, 4K video output, USB 3.0, Gigabit Ethernet and more computing power. The larger RAM, a new graphics core and two HDMI ports mean that more demanding projects can also be realized for dual-display applications. Rpi 4 takes a big step forward in terms of performance. As soon as a compute module version of Rpi 4 is available, Kontron will test its compatibility and use in industrial environments.

The company has now completed a number of commercial projects based on Rpi. The low initial price is not reflected in the end product for every project. It turned out that even for prototypes based on Rpi, customer consulting during implementation has a financial impact. In some cases, the resulting industrial platform cost as much as a standardized embedded platform. The suitability of Rpi therefore always depends on the respective purpose and application. However, the Industrial Starter Kit can be used to quickly determine whether a Raspberry Compute Module meets the desired requirements.

Andreas Schlaffer, Head of R&D at Kontron Austria / am