Embedded System Module
Encyclopedia
Embedded System Module, or ESM, is a compact computer-on-module
(COM) standard. An ESM module typically includes a CPU processor, memory, module-specific I/O interfaces and a number of basic front I/O connectors. They can be plugged on a carrier board or be used as a stand-alone processor card.
If the ESM module is plugged on a carrier, it relies on the standard PCI bus as a board-to-board interface. In this case two connectors create a link to the carrier. While the "J1" connector provides a specified PCI connection, the "J2" connector brings I/O signals from the ESM module to the carrier, which then includes all necessary connectors. The signal assignment of J2 is not fixed but can be completely customized, although there are reserved pins for a 64-bit PCI bus interface. A third connector, "J3", is used for additional I/O signals if the ESM module has no front I/O. The signal assignment of this connector is fixed to support a special set of I/O functions.
A large part of the I/O functions on ESMs are often controlled by an onboard FPGA component (field-programmable gate array) so that every module can easily be tailored to a specialized application through user-defined functions. Such functions are loaded into the FPGA as IP cores
. Using FPGAs also reduces dependence on special controller chips which may become obsolete, thus extending the card's availability.
ESMs are typically used on boards for CompactPCI
and VMEbus
as well as single-board computer
s for embedded applications. A company standard by MEN Micro, a manufacturer of embedded computers, specifies the ESM concept and the different types of modules. The ESM specification defines one form factor for the printed circuit board: 149 x 71 mm.
Depending on the processor type, most ESM modules have heat sinks and can be operated in wide temperature ranges up to -40 to +85 °C.
A mechanical specialty of ESM modules is that their connectors are compatible with the PCI-104 module standard. These modules can be "stacked" onto ESM modules, e. g., for additional peripheral interfaces.
Computer-on-module
A computer-on-module or System on Module is a type of single-board computer , a subtype of an embedded computer system. An extension of the concept of System on Chip , COM lies between a full-up computer and a microcontroller in nature.- Design :Today's COM modules are complete embedded computers...
(COM) standard. An ESM module typically includes a CPU processor, memory, module-specific I/O interfaces and a number of basic front I/O connectors. They can be plugged on a carrier board or be used as a stand-alone processor card.
If the ESM module is plugged on a carrier, it relies on the standard PCI bus as a board-to-board interface. In this case two connectors create a link to the carrier. While the "J1" connector provides a specified PCI connection, the "J2" connector brings I/O signals from the ESM module to the carrier, which then includes all necessary connectors. The signal assignment of J2 is not fixed but can be completely customized, although there are reserved pins for a 64-bit PCI bus interface. A third connector, "J3", is used for additional I/O signals if the ESM module has no front I/O. The signal assignment of this connector is fixed to support a special set of I/O functions.
A large part of the I/O functions on ESMs are often controlled by an onboard FPGA component (field-programmable gate array) so that every module can easily be tailored to a specialized application through user-defined functions. Such functions are loaded into the FPGA as IP cores
Semiconductor intellectual property core
In electronic design a semiconductor intellectual property core, IP core, or IP block is a reusable unit of logic, cell, or chip layout design that is the intellectual property of one party. IP cores may be licensed to another party or can be owned and used by a single party alone...
. Using FPGAs also reduces dependence on special controller chips which may become obsolete, thus extending the card's availability.
ESMs are typically used on boards for CompactPCI
CompactPCI
A CompactPCI system is a 3U or 6U Eurocard-based industrial computer, where all boards are connected via a passive PCI backplane. The connector pin assignments are standardized by the PICMG US and PICMG Europe organizations. PICMG stands for PCI Industrial Computers Manufacturers Group...
and VMEbus
VMEbus
VMEbus is a computer bus standard, originally developed for the Motorola 68000 line of CPUs, but later widely used for many applications and standardized by the IEC as ANSI/IEEE 1014-1987. It is physically based on Eurocard sizes, mechanicals and connectors , but uses its own signalling system,...
as well as single-board computer
Single-board computer
A single-board computer is a complete computer built on a single circuit board, with microprocessor, memory, input/output and other features required of a functional computer. Unlike a typical personal computer, an SBC may not include slots into which accessory cards may be plugged...
s for embedded applications. A company standard by MEN Micro, a manufacturer of embedded computers, specifies the ESM concept and the different types of modules. The ESM specification defines one form factor for the printed circuit board: 149 x 71 mm.
Depending on the processor type, most ESM modules have heat sinks and can be operated in wide temperature ranges up to -40 to +85 °C.
A mechanical specialty of ESM modules is that their connectors are compatible with the PCI-104 module standard. These modules can be "stacked" onto ESM modules, e. g., for additional peripheral interfaces.