An embedded system is characterized by real-time and multi-rate operations define the ways in which the system works, reacts to events and interrupts and schedules the system’s functioning in real time.
It does so by following a plan to control latencies and to meet deadlines.
The different operations may take place at distinct rates. The user of an embedded device is often not even aware that a computer is present in the device.
The computer is used primarily to provide flexibility and to simplify the system design. Unlike a PC, program code is usually stored in ROM and not a hard disk drive. Typically, the end user does not develop new software for the embedded device. With advances in VLSI technology, embedded systems have become so inexpensive that they are found in most of today’s electronic devices.
EMBEDDED SYSTEMS EVERYWHERE
Embedded systems span all aspects of modern life and there are many examples of their use.
Biomedical Instrumentation – ECG Recorder, Blood cell recorder, patient monitor system
Communication systems – pagers, cellular phones, cable TV terminals, fax and transreceivers, video games and so on.
Peripheral controllers of a computer – Keyboard controller, DRAM controller, DMA controller, Printer controller, LAN controller, disk drive controller.
Industrial Instrumentation – Process controller, DC motor controller, robotic systems, CNC machine controller, close loop engine controller, industrial moisture recorder and controller.
Scientific – digital storage system, CRT display controller, spectrum analyzer.
A microcontroller is a single silicon chip with memory and all Input/Output peripherals on it. Hence a microcontroller is also popularly known as a single chip computer. Normally, a single microcomputer has the following features
Memory for storing program
EEPROM for nonvolatile data storage
RAM for storing variables and special function registers
Timers and counters
Analog to digital converter
Circuits for reset, power up, serial programming, debugging
Instruction decoder and a timing and control unit
Serial communication port