A Guide to Embedded Computers

The word embedded in embedded computers refers to the computer being built into a product which uses the computer as part of the product. There is a computer for instance in a modern car, in fact there are a number of computers. One is probably used to control the combustion in the engine. Yet one is used to monitor and control aspects of the environment such as temperature and fans. They are all embedded computers.

Another expression to describe about the same thing is industrial computer. Embedded computers for industrial use is different from personal computers, found in an office for example, in important aspects such as lifecycle, input and output interfaces (I/O), the temperature range in which it’s designed to operate and the environmental challenges with which it can cope.

Personal computers have a typical product lifecycle of less than a year. So after less than a year the product is replaced by a new model, and during its lifecycle it normally undergoes several revision changes as well. The industrial computer commonly has a product lifecycle of five to seven years from introduction to the market. Revision changes are managed and documented in a formalized manner. Changes are readily communicated by the supplier to customers using the embedded computers.

Operation in demanding environments

The prolonged life time of the embedded computer is the answer to demands from companies integrating it into their products. Since the embedded computer is a tightly integrated part of their product, system, service and business even, it’s not acceptable to have to reintegrate a new computer should the existing break, after a year or so.

Embedded computers often need to have a wider range of I/O than commercial motherboards (found in personal computers). Usually there are also legacy I/O requirements put upon embedded computers. It means that older versions of I/O have to be included for integration in industrial products where existing functionality are accessible through older I/O only. Very often an interface for a TFT display, using for instance LVDS, is required in the embedded computer. This is a feature commonly not found on commercial motherboards.

A personal computer or laptop is designed for use in temperatures from +5°C to +45°C. The standard temperature range for an industrial motherboard or embedded computer is from 0°C to 60°C. Additionally, temperature requirements increase when the embedded computer is intended for use in trucks, boats or outdoors where the temperature is expected to be both warmer and colder from time to time. The so-called industrial temperature range indicates that the embedded computer will work just fine from -40°C till +85°C. It’s with few exceptions the widest temperature range in which an industrial computer can be expected to work.

Screenshot 2019-02-22 at 12.25.52 — The definitions, labels and phrases used to indicate the operating temperature of embedded computers vary in our industry. Hectronic applies the following definitions to the labels Extended and Industrial operating temperature ranges in our product pages:

The normal indoor environment, a domestic home or an office, is not particularly demanding to the personal computer. A train, car or truck presents more challenging environments. The embedded computer is required to withstand for instance vibration, shock, moist and dust without malfunctioning or breaking. A word often used to emphasize the embedded computers great properties in withstanding challenging aspects of the environment is rugged, or ruggedized.

Passive cooling of the embedded computer is the preferred cooling method to the industrial customer. A cooling fan is usually avoided if possible. The reasons are that the fan may break, is noisy and is dependent of air flowing bringing dust and dirt into the enclosure. The industrial requirement for passive cooling promotes development of low power processors and solutions as well as mechanical and thermal designs different from what’s found in personal computers. Another trend is that the industrial customer requires smaller and smaller embedded computers.

Processors in embedded computers

The same type of processors developed for personal computers are also used in embedded computers. Processors range at the low end from ARM-type processors running on battery up to high-end X86 processors, bringing performance similar to notebooks and servers to embedded applications.

Newly developed processors are released at first targeting personal computers and laptops. Selected processors are included in the vendor’s embedded roadmap, which means that they have long term availability. Vendors of X86 processors have lately begun to develop separate processor platforms (CPU and chipset) targeting consumer and embedded applications respectively.

Sometimes the processor platform for embedded applications is at a later stage introduced with options for operation in an industrial temperature range. In the past most X86 processors where not available specified for an industrial operating temperature range, and that’s often also the case today. Thus the board and system manufacturer need to optimize the design and perform temperature screening tests to be able to offer embedded computers specified for an extended or industrial temperature range.

Standard or custom made embedded computers

Companies that use embedded computers in their products have a strategic choice to make when deciding which type of embedded computer to use. It’s a choice between using a standard product, a partly custom made embedded computer or a full custom embedded computer.

An embedded computer in the form of standard product is developed to be used by more than one of our customers. A term often used for the standard product embedded computer is COTS, Commercial-Off-The-Shelf. The standard product has the advantage of being available for integration right away, without delay. There is a great variety of standard products to choose from. In limited volumes the standard embedded computer is often the more cost effective alternative. The product lifetime is often up to seven years.

Screenshot 2019-02-22 at 12.27.14 — Embedded computers in the standard product category are available in separate categories. The picture shows three category examples: the fanless box PC, the computer board and the Panel PC.

One downside to choosing a standard product is that it may be difficult to find one that matches the requirements perfectly. When the standard product is no longer available there may be problems to find a matching replacement. The product in which the computer is embedded may have to be redesigned for the new embedded computer to work.

Semi-custom – Combining standard and custom made

The second alternative is to use a partly custom made embedded computer. It’s typically built with two boards, the so called COM and the carrier board. COM, Computer On Module, is a board made up with the central components of the computer such as the processor, chipset and memory. The COM is mounted on the carrier board which is developed specifically to fulfill the requirements from the customer’s product.

Another expression for using a COM on a carrier board is applying the semi-custom strategy. The strategy combines the advantages from the standard product with the requirement to realize a solution unique to the product. The standard product COM is available right away and offers the core of the embedded computer without involving complicated development. The carrier board on the other hand is custom made and offers possibilities for adaptation in size, functionality and communication interfaces to match your requirements. A customized carrier board also offers the opportunity to integrate hardware unique to the customer’s application. Thereby the complete product is incorporated on the two boards. A complex solution built from several subsystems or boards are avoided.

1888_54fb438f — The semi-custom strategy is to use a standard product, the COM (the blue smaller board), Computer-on-module and mount it on a carrier board (the green bigger board) which is custom made.

A disadvantage choosing the semi-custom strategy is that the enclosure needs to be developed introducing challenges in leading the heat away from hot components and certification for instance according to the EMC directive. The semi-custom alternative is preferable when the annual volumes are a bit higher.

The third and last option is to go for an embedded computer that is completely custom made. At Hectronic we tend to call it the full custom strategy. All parts of the embedded computer are developed for maximum adaptation to the requirements and full product uniqueness. The advantage is that you can influence every aspect of the embedded computer and get a unique board or system optimized for the application. There is still the possibility of reusing the vendor’s processor platform design (the COM module in the semi-custom design). A somewhat larger annual production volume is needed to justify the cost generated by development.

Hectronic’s products and services

In addition to the above alternatives Hectronic offers support from development of the BSP, Board Support Package. BSP is a package of low-level software needed for the operating system to work on the embedded computer. Hectronic manages production of the standard products developed by us and the full custom computer boards and systems designed specifically for individual customers.

The responsibility for production includes keeping track of availability of components, when needed replacing components that are no longer available and verifying that the embedded computer works exactly like before. We call it maintenance.

Finally, from time to time, embedded computers go end of life and need to be replaced. We have great experience in developing a replacement. And we can manage to do that and still keep the exchange of embedded computer in the product as simple as possible.

Hopefully we managed to introduce you to our world of embedded computers. You are always welcome to contact us to discuss how your company, your products and your business can benefit from having embedded computers from Hectronic embedded in your product.

A Beginner's Guide to Embedded Computers: Everything from Hardware to Certification

Guide to embedded computers