Advanced System-on-Module (SOM): Accelerate Time to Market for Connected IoT Applications

Chapter 1

Introducing Advanced, Highly Integrated System-on-Modules (SOMs)

An Advanced, Highly Integrated System On Module (SOM) is a printed circuit board (PCB) with core components of an embedded processing system, designed for connected IoT Applications such as LTE Cat M1 / NB-IoT. 

Figure 1: LTE CAT M1/ NB-IoT S-2CONNECT Creo SOM

S-2CONNECT Creo-SOM by TT Electronics is an advanced, highly integrated System-on-Module (SOM) board for connected IoT applications.

It offers a robust and cost-effective embedded system-on-module platform for building industrial IoT products.

Featuring a powerful processor and cellular connectivity for global coverage, they deliver the perfect communication bridge providing real real-time sensing and positioning data. S-2CONNECT Creo SOM enables fast IoT development to connect, track, sense, and monitor devices.

A SOM board is not a "ready-to-use product." It needs to be incorporated into a surrounding environment, mainly consisting of a carrier board and a mechanic design.

The carrier board will carry all connectors for external peripherals and electronic components to convert the SOM-board signals to more appropriate signal levels suitable for the chosen interfaces. The carrier board also potentially carries power supply components with on/off functionality, LED, and pushbuttons.

In this case, the mechanical design means an enclosure or mounting concept for installing the carrier board and the SOM board inside another product. 

SOMs available to the market in 2022 have been optimally designed for space, functionality, and ease of use. SOMs come with ready-to-use operating systems: software drivers, schematic design, security, and wireless connectivity.

They also include integrated support for popular development environments, frameworks, and third-party applications. An edge connector is available for all interfaces. The interfaces are connected to connectors or application-specific components on the carrier board by plugging the module into it. A carrier board is often simple to build, as all the complexity is contained within the module.

When built into connected Industrial IoT products, SOMs have many advantages as single-board computers (SBCs) and  "chip-down" development. SOMs include a processor, memories, and communication interfaces. The components integrated on a SOM need a high level of interaction for speed, timing, and databus bandwidth. 

Not utilizing the advantage of a SOM could increase your project cost—more time wasted in design and increase in development cost, slower time to market. To help put the value into perspective, consider designing complicated core processing circuits; a manufacturing test system's price could eclipse an NRE budget, not to mention blow through the project timeline.

Chapter 2

The Challenges of Building the Entire Circuit Board In-House

Embedded electronic products are getting more and more advanced. The more frequent usage of high-level programming languages requires more powerful processors, more significant memories, and everything running on higher clock frequencies. The electronic design of a PCB with an advanced processor, memories, and other support circuits is not trivial. It requires a high level of expertise that many electronic designers find unfamiliar. High-speed data and address bus between processor and memories is a delicate process that must be carefully designed to run perfectly. 

Suppose you're considering building the entire circuit board and proceeding with a "chip-down" design. In that case, you must first have a sound understanding of your engineering team's capabilities: Do they have the expertise needed in low-level kernel software? Do they have the technical experience to execute swiftly without numerous board re-spins? Do they understand security? Does your team have the resources to take on this product development and all of your other engineering work?

The development team does not need to deal with these highly technical challenges using a SOM board. They've already been taken care of, making this one of the primary reasons for working with a SOM board. 

Chapter 3

Why Base a Design Around a System-on-Module (SOM)

There are several good reasons for choosing to base a design around a SOM board, and some are listed here:

1. Accelerate time to market
2. Reduce the risk of failing
3. Volume adoption

3.1 Accelerate time to market

There are three main reasons why the time to market can be shorter for a product based on a SOM board. 

• Faster electronic design and software development
• Simplified production process
• Fewer R&D costs associated with lengthy development schedules

3.1.1 Quicker electronic design

The most advanced part of the electronic design is already taken care of when working with a SOM board. The development team can focus on developing a carrier board which means little work compared to developing a complete product from scratch.

3.1.2 Software development can start earlier

The typical way of developing electronic products is by first doing the electronic design and building up a prototype PCB. Software development doesn't start until there is a working PCB available. 

When working with SOM, the software development can start before the electronic design is initiated. Software developers have access to a SOM board and development boards from the beginning. They do not need to wait for the electronic design to be ready before starting the software development.

3.1.3 Simplified production process

Setting up electronic production, including the process of testing and verifying the products, can be both time-consuming and costly, and it requires many engineer hours. By working with a SOM board, the production process can focus only on the carrier board and thus be much simpler and easier to set up.

3.2 Reduced risk of failing

Creating an electronic design with advanced high-speed processor and external memories is not simple. There is a high risk of failing with the first attempt of doing PCB layout. There are some "rules" to follow when designing a PCB with high-speed data and address buses. If those rules are not followed, there is a significant risk that the processor with memories will not work at all, or at least not work correctly. 

It might require several iterations before a perfectly operating PCB is obtained. Re-working costs money and consumes time. 

High-speed data and address buses emit radio frequencies. There is a non-negligible risk of failing on EMC during approval tests, which might lead to re-work and new rounds of approval tests, but most of all, it will cost time. 

Working with a SOM board reduces risks significantly compared to doing the entire design from scratch. 

3.3 Volume adoption

When exploring the total cost of ownership (TCO) for a product, it does consist of production cost for the device and development cost for the product. Development cost or NRE (Non-Recurring Engineering) is typically divided by the number of devices produced.

Example:

With a total NRE cost of $500,000, the NRE cost/device will be:

Total number of devices: 1,000 = NRE cost of $500/device

Total number of devices 100,000= NRE cost of $5/device

Production cost/device is changed with volume, but in the example below, this has been ignored to give a more simplified comparison.

Example with a total volume of 1,000 devices:

Example with a total volume of 100,000 devices:

The examples show that when TCO is calculated, it is undoubtedly cheaper to go for a solution based on SOM boards versus a fully developed solution for smaller volumes of devices (1000pcs). 

The examples also indicate that when reaching a higher volume, it will be more expensive to base a product on a SOM board, but even then, the advantage of a shorter time to market will still be there. 

A reasonable approach for companies looking for a high volume of products would be to start with a product based on a SOM board to keep time to market short. Then, develop an own single board solution to be launched and replace the SOM-board-based solution when the time is right. 

The TCO cost model described above is simplified. In real cases, there are other costs to consider. One of them is product maintenance cost. During the lifetime of a product, components might become obsolete, which can require a redesign of the product. When basing a product around a SOM board, the product maintenance cost for the SOM board lies on the supplier of the SOM board. The maintenance cost for your final product will be lower compared to having an own developed single board solution.    

Chapter 4

Important Considerations To Make When Selecting a SOM for your Connected IoT Application

When evaluating a solution for connected IoT applications, several aspects should be considered: 

1. R&D Time, Risk, and Cost
2. Security
3. Future-Proofing
4. Ecosystem

4.1 R&D Time, Risk, and Cost

Design teams should look for an all-inclusive solution that enables high-speed prototyping and accelerates development time. The solution should consist of an end-to-end framework that seamlessly delivers hardware, connectivity, infrastructure, and user experience solutions. By streamlining the secure connection of products and systems, users achieve tangible results such as improving efficiencies, eliminating unnecessary maintenance, reducing carbon footprint, and enabling data-led business decisions. So you can reduce your engineering investment, limit your R&D risk exposure, and get your product to market faster.

4.2 Security

You should not take security lightly, and the solution needs to support the relevant security standards for the Industrial Internet of Things. This means the system is built around a hardware root-of-trust and includes support for a secure and measured boot with remote attestation of software applications. Additionally, the security solution needs to adapt and keep pace with evolving threats over connected IoT equipment's typical 10-20 year industrial lifecycle. 

4.3 Future Proofing

The platform should provide futureproofing. Something like a Cat M1/NB2 + GSM/EGPRS that enables a global cellular coverage, allowing the device to relay data through diverse interfaces available on the SOM, which enable both hardware and software updates, even after the systems have been launched in the field via over-the-air (OTA) updates. It would also be highly beneficial to have the radio module equipped with a GNSS receiver for positioning. 

4.4 Ecosystem

The solution should showcase a vast ecosystem with an assortment of services and solutions, including complementary hardware, software, and pre-integrated tools within a scalable platform. And the solution should be equipped with accelerated application libraries to give software developers the same head start on the design that reference designs do for hardware developers. Advanced, highly integrated SOMs bring the time-to-market advantage of a SOM-based solution, but with a powerful processor and cellular connectivity for global coverage. They deliver the perfect communication bridge providing accurate real-time sensing and positioning data, making it an ideal approach for building industrial IoT products.

Chapter 5

Summary

Engineering teams are often challenged to deliver a solution/product within pressing timelines coupled with numerous new additional requirements, leading to plausible risks. It's challenging and almost impossible for product companies to keep pace with the changing technology and new CPU launches every quarter. Therefore, deciding to buy a qualified and well-tested off-the-shelf SOM board is one way of hedging the dynamic changes in the semiconductor industry. 

Keep in mind that developing an electronic product costs a lot of money and many months of effort. On top of that, there is another cost for maintenance and upgrading the design.

When buying a SOM board, one would have to pay more on the per-unit cost, but at the same time save a lot on development costs and on time spent on development. 

Quite obviously, at lower volumes (up to 1000 annual quantity), buying off-the-shelf SOM boards is the ideal and easy choice, while at larger volumes, things get a little interesting and tricky. Many companies fall for the temptation to build on their own, not realizing the possible pitfalls associated with this traditional approach. The prime deciding factor is often not the cost but factors like time to market, the complexity of designing in-house, and related maintenance/support costs.