System on module
[Image:ARMSoCBlockDiagram.svg|right|275px|thumbnail|Typical SoC use in a system on a module circuit board]
A system on a module is a board-level circuit that integrates a system function in a single module. It may integrate digital and analog functions on a single board. A typical application is in the area of embedded systems. Unlike a single-board computer, a SoM serves a special function like a system on a chip. The devices integrated in the SoM typically require a high level of interconnection for reasons such as speed, timing, bus width, etc. There are benefits in building a SoM, as for SoC; one notable result is to reduce the cost of the base board or the main PCB. Two other major advantages of SoMs are design-reuse and that they can be integrated into many embedded computer applications.
History
The acronym SoM has its roots in the blade-based modules. In the mid 1980s, when VMEbus blades used M-Modules, these were commonly referred to as system On a module. These SoMs performed specific functions such as compute functions and data acquisition functions. SoMs were used extensively by Sun Microsystems, Motorola, Xerox, DEC, and IBM in their blade computers.Design
A typical SoM consists of:- at least one microcontroller, microprocessor or digital signal processor core
- *multiprocessor systems-on-chip have more than one processor core
- memory blocks including a selection of ROM, RAM, EEPROM and/or flash memory
- timing sources
- industry standard communication interfaces such as USB, FireWire, Ethernet, USART, SPI, I²C
- peripherals including counter-timers, real-time timers and power-on reset generators
- analog interfaces including analog-to-digital converters and digital-to-analog converters
- voltage regulators and power management circuits