Embedded systems have substantially different design constraints. No single characterization applies to diverse spectrum of embedded design. However, some combination of cost pressure, long life cycle, real-time requirements, reliability requirements, and design culture dysfunction makes the characterization .The extreme diversity of embedded system makes the generalization more difficult. Nonethless, the interest in the entire range of embedded system is emerging. Embedded systems require high life cycle. Embedded systems support ease of up-gradation. Embedded systems find applications in every field where the technology up-gradation is more vital.
Embedded VoIP Gateway:
Access Networks has developed a VoIP gateway using embedded design. The design is a distributed system, which uses a ARM7 TDMI microcontroller as a processing unit and a Teak Lite DSP core as the sensors/actuators. The microcontroller controls the entire system and provides interface for the external environments provides the signal processing operations required for the gateway to handle the calls. The basic idea of distributed design is the high-speed communication that is required. DSP performs signal processing alone hence there will be high speed. The microcontroller performs high speed controlling operations such as data transfer between DSP and external environment.
The DSP performs signal-processing operations such as digital to analog/analog to digital conversion, filtering, basic coding etc. Some DSPs provide different CODEC operations. They can also provide Subscriber Line Interface Circuit (SLIC) need to handle the telephone functions such as off hook and on hook.
The microcontroller performs data transfer and external call handling functions. It also performs the protocol conversion of data. It provides interface to external environment. The software loaded in the processor performs all the required tasks. With the ease of up-gradation, the software can be changed without disturbing the hardware and its functionalities. Embedded systems provide ease of technology up-gradation with less investment. There are some certain design criteria, which should be answered while designing