Embedded systems come in a variety of shapes and sizes ranging mostly from a just a microcontroller chip to a full scale multi core microprocessor based desktop PC level systems. It all depends on the processing power requirement and level of integration for the user. Computer on modules (COM) are highly integrated computer modules based on the COM Express form factor (just as ATX is a form factor for desktop PC’s). System on modules are used just like normal Integrated Circuits (IC’s) but are actually composed themselves of multiple other IC’s, the microprocessor (core), RAM & ROM (memory) and other necessary peripherals.
COM Express uses the single differential signaling technology. Computer on modules have their inputs and outputs mapped on pins for interfacing with or installation on the external circuit board. As CoM’s themselves, unlike a single board computer (SBC), are equipped with just the necessary hardware to perform as a PC, every other peripheral, connectivity interface (Serial, USB, Ethernet, etc), power supply and dedicated functionality (the application circuit) is provided on the external circuit board which is known as Carrier or Base board. This brings with it the advantage of using only those peripherals and interfaces for our application which we require. This also eliminates the hassle of designing critical, high-speed and impedance matched PCB’s (Printed Circuit Boards) for our application. Because the basic architecture is defined, a lot of design work is eliminated and one can spend more time on developing the application software and carrier board resulting in shorter net development times. For majority of the applications, single board computer are not used due to their fixed hardware and so higher cost. Computer on modules on the other hand are the most favorite option for embedded systems developers and manufacturers due to their inherent flexibility and lower cost.
The modularity, scalability and elasticity in the computer on modules design makes it suitable for all types of application areas whether medical, automation, instrumentation and military. One can build great HMI’s (Human Machine Interfaces) using CoM’s which is a big part of embedded systems market. System on modules support all major types of operating systems that is Linux, Windows, etc. Usually the development is done on a desktop PC and then the developed application software is transferred into the memory of CoM’s through serial or JTAG (Joint Test Action Group) port present on their carrier boards.