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Custom hardware design considerations

Currently there are more than ever ready-made off-the-shelf hardware solutions available, but those solutions do not fit all the applications. There are many good reasons to design custom hardware and software for an embedded systems application. This article tells you what to consider when choosing a technical solution for a product containing information technology and at the beginning of the design process.

When you build a full custom design, you can freely control the features of your product. When you design your own custom hardware, you will have full control over product designs and IPR.


There are many applications where one part of the larger device needs to be replaced with a new device built using new technology. If you want to design a product of exact size or replace a component in an old one and have specific needs for it’s look and feel, you often need to do custom design.


Environmental conditions, like required wide temperature range and need to withstand hard environmental conditions mean that you need to do some custom design for both the product enclosure and the electronics within. There are also devices that need physical security that prevent the user from opening the device. Sometimes there are special connectors and proprietary interfaces that can be easily supported only with custom designed hardware.


Energy efficiency and manufacturing price are good reasons to consider for the design of custom hardware. By selecting right components for the application, it is possible to optimize energy consumption and cost of component. By specifying a processor that is right for the application instead of using a much more powerful than needed saves energy and is usually more cost efficient.


A custom design can be designed for a long product life cycle in mind. The long product life can mean the long operating life of product and possibility to keep the product in the manufacturing for a long time.


Custom hardware design

Choosing custom embedded hardware over Commercial Off-The-Shelf (COTS) hardware depends on several factors. What should you consider in 2025 before making the decision?


The designer has a lot of choices to make when deciding to custom hardware. There are many considerations for a custom hardware design that needs to be verified early in the development process.


One major decision is the choice of microcontroller or an application processor when planning the application at a design stage. Another significant factor is the choice of the operating system. These choices are often interlinked to each other.

The first design choice will be to decide between a microcontroller (MCU) or an application processor (CPU). The choice could also be that there are both MCU and CPU in the same design, for example so that MCU handles the real time task and CPU handles the higher-level functionality (like communications and user interface).

Another thing to consider is the operating system for the design. Typical choices are Linux and different real time operating system (RTOS). When you use Linux, typically a CPU with memory protection and at least several megabytes of RAM is needed. With a small RTOS in many applications an MCU with just few hundred kilobytes of memory is enough.


On the business perspective the manufacturing cost target, estimated production volume and planned production lifetime are essential details that needs to be defined. The intended lifecycle of the product, production volumes and the choice of components are important factors. In addition to those the supply chain issue and regulatory requirements need to be carefully considered. Custom hardware makes sense also in products where low production costs in mass production are more important than up-front development costs.


Designing custom hardware design, especially for completely new products, starts often with rapid prototyping. Rapid prototyping is a key enabler in modern innovation in embedded systems field. If the new product being designed is a successor or replacement for an existing product, usually more or less design re-use from the previous product makes sense.


Nowadays it is easier and faster than ever to build a prototype. There are many “maker” products and evaluation boards that make is possible to build hardware prototypes easily. What you can build with these can be almost the real thing. But they are not market-ready products – actually, those prototypes are quite far from it. There is a lot of work to be done to move from a proof of concept to a market ready product.




Levels of customization

When designing an electronics product, the choice between using an off-the-shelf hardware or designing a full custom hardware design is not a black and white selection. There are many different variations of customization levels that can be chosen for the product.


On the hardware side the least customized option is to use a desktop PC, laptop or an industrial computer to run your application.

When off-the-shelf hardware cannot be made to work for a product, some level of custom hardware design is required. Circumstances that call for custom hardware include situations where mechanical or electronics requirements cannot be met by off-the-shelf-hardware.


Single board computers (SBCs) are well-suited for embedded systems where space, power consumption, and reliability are critical considerations. SBCs installed inside a custom application-specific enclosure can fit into multiple applications such as industrial automation, automotive control systems, medical devices, and IoT deployments.

Next step after SBC for more customization to use Computer-on-Modules (COMs). COMs are small circuit boards that are plugged into standardized connectors on an application-specific carrier board. This COM approach enables engineers to cost effectively design innovative solutions within the shortest time to market and to stay highly agile to adapt to technical evolutions. The development and testing typically starts on a standard carrier board and then on an application-specific custom carrier board with the purpose-built circuit parts is designed.


There are applications where it makes sense to get rid of the connectors between the carrier and computer module. There are computing modules that can directly soldered to a circuit board or even customized.


In the full custom design approach, the device is designed from ground up for this specific application in mind. With custom hardware, the electronics can be sized and shaped to match the mechanical requirements for this special application. Once the sales volumes counterbalance the NRE costs, the overall cost of the custom hardware product will be far less than an off-the-shelf (COTS) product.



The engineering effort needed to make a custom solution depends on the level of customization and experience in designing them. Designing a customized carrier board is less complex than a full custom design.


The product development from idea to a product using traditional full custom design route typically takes often 8-12 months from concept to deployment. Accelerated development where product uses computing modules development typically takes 4-8 months depending on level of customization level.


The use of pre-certified RF modules for easier to get RF related certifications for your device. Using tested and known good hardware designs makes design faster and increases the reliability of your end products.


Tested and known good hardware designs can come from the Convergens design knowledge, component manufacturer application notes or from the previous product or component manufacturer application notes. Re-use of known software modules (operating system, drivers, libraries) makes software development easier and faster.


Convergens

CVG Convergens is a long-term partner that offers services over the entire life cycle of products and systems containing electronics. We offer services for the development of embedded systems, from business-level analysis to the implemented product and realized added value. We have solid experience in both software and physical hardware solutions.


CVG Convergens has almost 30 years' experience in designing electronics products that contain embedded systems. We have solid experience in all aspects for embedded systems: concepting, developing, manufacturing and sustaining products for our clients on long-term basis.


We have developed over 500 different products. Over million product units are manufactured by us or based on our designs. Typical products that we develop include single-board computers, computing/control modules, IoT sensors and actuators, communication gateways, HMI devices, mobile handheld devices and associated software.


In addition to development, we provide services over the product life cycle including engineering, compliance and certifications, NPI, manufacturing and sustaining.

This article is based on the presentation “Custom vs off-the-shelf – perspectives for 2025” presented by Tomi Engdahl at Embedded Conference Finland 2024.

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