What is a System-on-Module (SoM)? Exploring Its Role in Electronics Design

With the rapid advancement in electronics, understanding the different components that make up complex systems is crucial. One such component gaining popularity is the System-on-Module (SoM). But exactly what is a system on module? In this article, we will explore what a System-on-Module is, how it differs from a System-on-Chip (SoC), and its significance in modern electronic design.

What is a System-on-Module (SoM)? 

We have all heard of microcontrollers, microprocessors, and System-on-chips. But what is a system on module, how are they different from SoCs, and how can they be helpful in the development of electronic systems?

Differences Between System-on-Module (SoM) and System-on-Chip (SoC)

A System-on-Module, or SoM for short, is an electronic circuit that integrates all needed system functions into a single module, including a processor, memory, and I/O controllers. However, unlike an SoC, which combines many of these functions onto a single chip, an SoM typically only requires a source of power to operate.

Technical Differences:

• Integration Level: SoCs integrate multiple system components such as CPU, GPU, and MMU onto a single silicon chip. In contrast, SoMs consist of multiple chips (including the processor, memory, and I/O controllers) mounted on a single module.
• External Components: SoCs still require external components like memory and I/O controllers to function, whereas SoMs are more self-contained and only need a power source.
• Design Flexibility: SoMs provide greater flexibility in design as they can be easily replaced or upgraded without changing the entire system, unlike SoCs which require a complete redesign for upgrades.

Implications in Design:

• Thermal Management: SoCs can have complex thermal management requirements due to their dense integration, whereas SoMs distribute components across a module, potentially easing thermal design constraints.
• PCB Complexity: Using an SoM can simplify PCB design as it reduces the number of components that need to be integrated on the main board, in contrast to SoCs which require careful routing and placement of numerous external components.
• Development Time: SoMs can significantly reduce development time by offering pre-integrated and tested modules, whereas SoCs require more extensive development and testing phases.

SoMs are not as common as SoCs, but as semiconductors approach their physical limits, the role of SoMs will become increasingly important[^2^].

GHI Electronics SITCore IoT System-on-Modules

To delve deeper into the technical aspects of SoMs, let's consider their design. A typical SoM integrates digital and analog functions on a single board. It includes at least one microcontroller, microprocessor or digital signal processor (DSP) core. Memory blocks, including a selection of ROM, RAM, EEPROM and/or flash memory, are also integral parts of an SoM. Timing sources, industry-standard communication interfaces such as USB, FireWire, Ethernet, USART, SPI, I²C, and peripherals including counter-timers, real-time timers and power-on reset generators are also incorporated into the design[^3^]."

SoMs are often built on top of a PCB and can either be enclosed in a metal housing (for EMC compliance) or left exposed with all components showing. Furthermore, SoMs always have a method for connecting to external boards in the form of pins, edge connectors, or solder tabs.

While the Raspberry Pi and Arduino range of boards could be considered SoMs, they fall into different categories. A Raspberry Pi is a single-board computer that has no specific purpose, and the Arduino range of boards are prototyping environments that break out the pins to a microcontroller.

How are System-on-Modules helpful for electronics?

SoMs are not as common as SoCs, but as semiconductors approach their physical limits, understanding what is a system on module and its role will become increasingly important. SoCs are chips that integrate multiple system components into a single device, such as a CPU, GPU, and MMU. However, an SoC still requires external circuitry to enable the device to operate, and this can include memory, I/O controllers, and various other supporting components. 

Advantages of Using System-on-Modules in Electronic Design 

As such, using SoCs in designs can make the design process complex and tedious. A designer needs to fully understand how to properly use an SoC, including each pin's function, thermal properties of the SoC, and pad design. An SoM, however, creates a module that handles these complexities to produce a device that a designer can essentially drop into a circuit.

Benefits of SoMs:

• Reduced Complexity: SoMs reduce the complexity of the design process by integrating key system functions into a single module, thereby minimizing the number of components a designer needs to manage.
• Interchangeability: SoMs can be easily swapped out for upgrades or replacements, which is particularly beneficial in industries where technology rapidly evolves, such as telecommunications and consumer electronics.
• Reliability: SoMs are often pre-tested and validated, ensuring high reliability and performance in final products, which can be critical for applications in medical devices, automotive systems, and industrial automation.
• Application Versatility: SoMs can be used in a wide range of applications, from simple consumer gadgets to complex industrial machinery, making them highly versatile.

As Kenneth A. LaBel, a leading expert at NASA, once said, 'The complexity of SoCs drives all aspects of their design and application. Despite the challenges in radiation tolerance, testability, and fault isolation, the potential savings in size, weight, and power, as well as increased system performance, make SoCs a compelling choice for aerospace technology developers[^4^]

Like the Arduino, the pins of an SoM can be directly connected to whatever hardware the designer wants to use (assuming they are not drawing too much current or using incompatible voltage levels). However, where an Arduino is a prototyping platform, an SoM can be used in the final product with a high degree of reliability (enough for commercial products).

Another major advantage of using an SoM is interchangeability. Assuming that a manufacturer of an SoM keeps the form factor of the module, improvements in technology can be incorporated into updated SoMs, which can easily be interchanged with older units. As such, expensive, complex systems (such as data centres and cellular networks) can be upgraded without completely changing the underlying hardware. Furthermore, the older SoMs can be recycled by using them in older designs at a discount price (assuming that the SoM itself is generic enough to allow for use in another application).

To illustrate the practical application of SoMs, let's consider the case of Sun Microsystems, Motorola, Xerox, DEC, and IBM. These tech giants extensively used SoMs in their blade computers in the mid-1980s, performing specific functions such as compute functions and data acquisition functions[^5^].

Real-World Examples of System-on-Modules

If we go with the definition of an SoM as being a device that allows for use in an end-product and combines multiple system functionality into a single PCB, the answer is that System-on-Modules are very common in the industry.

Real-World Examples:

• ESP32-WROOM-32: This SoM integrates a microcontroller, TCP/IP stack, radio circuitry, radio antenna, and memory onto a single PCB with a metal enclosure. It is widely used in IoT applications for providing Wi-Fi and Bluetooth connectivity.
• SAMA5D27 by Microchip: This SoM integrates an Arm Cortex A5 processor with 1Gb DDR2 DRAM, an onboard power management unit, and requires a single 3.3V input. It is used in applications ranging from industrial automation to consumer electronics.
• NVIDIA Jetson Nano: This SoM includes an ARM CPU and NVIDIA GPU, designed for AI and machine learning applications. It is used in robotics, smart cameras, and IoT edge devices.

Case Studies:

• Healthcare Devices: SoMs are used in portable medical devices where reliability and compactness are critical. For example, an SoM might be integrated into a handheld ultrasound device, providing the necessary processing power and connectivity in a compact form factor.
• Automotive Industry: SoMs are employed in advanced driver-assistance systems (ADAS) where they provide high-performance computing capabilities needed for real-time processing of sensor data.
• Industrial Automation: In industrial settings, SoMs are used in programmable logic controllers (PLCs) and human-machine interfaces (HMIs), offering robust and scalable solutions for complex automation tasks.

One area of electronics that sees heavy use of SoMs is radio communication, specifically the 2.4GHz band. The ESP32-WROOM-32 is an example of an SoM that integrates a microcontroller, TCP/IP stack, radio circuitry, radio antenna, and memory, all onto a single PCB with a metal enclosure. While there are versions of this module attached to a board with pins for prototyping, the module itself is available for purchase and can be soldered directly onto PCBs in a final product to either act as a Wi-Fi adaptor or to operate as the sole controller.

Another example of an SoM is the SAMA5D27 by Microchip. This SoM integrates an Arm Cortex A5 processor with 1Gb DDR2 DRAM, integrates an onboard power management unit, and requires a single 3.3V input. A variation of this SoM is the SAMA5D27 Wireless SOM, which integrates Wi-Fi and Bluetooth connectivity while also offering a larger memory size of 2Gb (256MB). These SoMs are designed to provide designers with an entire ARM platform that can be directly added to a final product and removes the need for the designer to search for appropriate components, correctly route PCBs, and debug hardware.

Future of System-on-Modules in Electronics 

In a word, the SoM is what the CPU was to computers before introducing the Intel 4004. Sure, you can design a CPU from scratch using discrete transistors, but an off-the-shelf CPU has done the hard work for you already. Thus, next time you need to integrate a complete system into your design, take a look at some SoMs and see if they can save your project time and effort.

Conclusion

In conclusion, knowing what is a system on module and how it represents a significant advancement in electronics design, offering a compact, efficient solution for integrating complex systems. As technology continues to evolve, SoMs will play an increasingly vital role in various applications, from IoT devices to industrial automation. By understanding what a System-on-Module is and its benefits, designers can make informed decisions to optimize their projects. 

References:

1. "System on module - Wikipedia." Accessed June 7, 2023. Link
2. "System on module - Wikipedia." Accessed June 7, 2023. Link
3. "System on module - Wikipedia." Accessed June 7, 2023. Link
4. LaBel, Kenneth A. "System on a Chip (SoC) Overview." NASA, 2010. Link
5. "System on module - Wikipedia." Accessed June 7, 2023. Link