What is a System-on-Module?

What is a System-on-Module?

A system-on-module (SOM) is a compact, fully-integrated circuit board that contains all the necessary components of a computer or other electronic system on a single module. It's designed to be plugged into or otherwise connected to a carrier board, which provides the external interfaces and connectors needed for the SOM to interact with the rest of the system or device. Key components typically included in a SOM are:

• Central Processing Unit (CPU): The CPU core, often an ARM-based processor for low-power applications or x86 for higher computational needs, acts as the computational heart. It executes the system software and application codes, and then orchestrates data processing workflows tailored to specific application demands.
• Memory Architecture: Incorporates volatile and non-volatile memory elements. Volatile memory typically comprises DDR3/DDR4 SDRAM for high-speed data access, critical for running applications and the operating system. Non-volatile memory, such as eMMC or NAND flash, is provisioned for persistent storage of the OS, firmware, and application binaries.
• I/O and Peripheral Interfaces: A comprehensive suite of I/O interfaces is embedded to ensure versatile connectivity options. This includes high-speed interfaces like USB 3.0/2.0, Gigabit Ethernet for network connectivity, and lower-speed interfaces like I2C, SPI, and UART for peripheral and sensor integration. High-definition multimedia interfaces, such as HDMI or LVDS, support sophisticated display and multimedia functionalities.
• Wireless Communication Modules: Advanced SOMs might embed wireless communication modules, integrating Wi-Fi, Bluetooth, and sometimes GNSS modules, to facilitate IoT-ready applications requiring remote data transmission and location services.
• Power Management ICs (PMICs): These integrated circuits are meticulously designed to manage and distribute power across the SOM’s components efficiently. They ensure operational stability across varying load conditions and manage power sequencing to prolong system reliability and battery life in portable applications.

System-on-Module vs. System-on-Chip: What's the Difference?

The terms "System-on-Module" (SOM) and "System-on-Chip" (SoC) both refer to solutions that integrate multiple functional components into a single system to streamline design and development processes in electronics. 

However, they represent fundamentally different approaches and are used in distinct contexts within embedded systems and electronics design. Understanding the differences between SOM and SoC is crucial for engineers, designers, and decision-makers involved in product development. Below are the key differences between a System-on-Module and a System-on-Chip:

• Integration Level: SoCs represent the highest level of integration by embedding all essential electronic components into a single silicon chip. SOMs, while highly integrated, are modular circuit boards that combine a SoC with additional critical components.
• Development Complexity and Cost: Developing a custom SoC involves significant upfront design work, making it suitable for high-volume productions. SOMs, offering modular integration, significantly reduce development complexity and cost, making them ideal for a wide range of production volumes.

• Flexibility: SOMs provide greater flexibility in design and updates, allowing for easy upgrades or modifications by swapping the module. SoCs, being very integrated designs, do not offer this level of flexibility post-manufacture.
• Application: SoCs are commonly used in consumer electronics (smartphones, tablets) due to their high integration level – they’re as compact and power efficient as possible. SOMs are preferred in industrial, medical, and IoT applications, where customization, flexibility, scalability, and time-to-market are key considerations.

How do System-on-Modules Work?

The architecture of a SOM is designed for seamless integration with a carrier board, which provides the necessary connectors and interfaces for peripheral devices. This modularity allows for a high degree of flexibility and scalability in system design. 

The communication between the SOM and other hardware components is facilitated through these connectors, allowing the SOM to interact with and control various peripherals and devices within the larger system. 

Integration with Carrier Boards

SOMs are designed to mechanically attach to a carrier board via high-density connectors. These connectors carry a multitude of signals between the SOM and the carrier board, including power supply lines, communication interfaces, and control signals. 

The carrier board typically provides the physical interfaces for these signals, such as RJ45 jacks for Ethernet or USB ports, and connects to other custom hardware required for the application. 

This configuration results in developing a flexible Single Board Computer (SBC) platform. These SBC platforms can be customized to meet the specific requirements of your project, with selections made from a range of processors, memory, wireless, and I/O options that best match the performance and functionality needs of your product. At Ezurio, we specialize in helping build your custom SBC solution needs. 

Pin Mapping and Configuration

The SOM's pinout is meticulously designed to maximize functionality and flexibility. Design engineers must carefully map these pins to the appropriate functions on the carrier board, considering the requirements for impedance matching, signal integrity, and routing constraints, especially for high-speed signals.

Communication with Peripheral Devices

SOMs come equipped with a variety of communication interfaces to interact with external devices. These include: 

• I2C: utilized for low-speed device control.
• SPI: suitable for higher-speed peripherals.
• UART: used for serial communication.
• PCIe: facilitates high-speed data transfer to external components such as SSDs or FPGA modules. 

GPIO (General-Purpose Input/Output): 

For more direct control or interaction with external hardware, SOMs offer GPIO pins that can be configured either as input or output.

These pins play a crucial role in interfacing with sensors, actuators, and other digital components, enabling a wide range of application-specific functionalities.

Software and Firmware Integration

Upon power-up, the SOM executes code from a bootloader stored in non-volatile memory, which initializes the hardware components on the module and loads the operating system (OS) into RAM. 

The choice of OS can vary, including options like Yocto Linux, Buildroot Linux, Android, Ubuntu, Zephyr RTOS and FreeRTOS. Real-time operating systems (RTOS), such as Zephyr RTOS and FreeRTOS are used in applications where timing is critical, while more comprehensive systems like Linux are suited for complex applications that require advanced functionalities.

Driver and Middleware Support:

For a SOM to effectively communicate with peripherals and execute application-specific tasks, appropriate drivers and middleware are required. 

These software components abstract the hardware complexity and provide APIs (Application Programming Interfaces) for application development, streamlining the process of software creation and integration.

Application Software Development

With the foundation provided by the OS, drivers, and middleware, developers can focus on writing the application software that runs on the SOM, tailored to the specific needs of their product. This software can leverage the full capabilities of the SOM, from processing power to connectivity options, to perform its intended functions.

Related Reading: Is Your Wireless SOM Certified? What Boundary Devices and Ezurio Bring to the Table

Benefits of Using a System-on-Module in Embedded Applications