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MICROCONTROLLERS MADE EASY

Flash

Flash is an electrically erasable and programmable memory. It can be used instead of ROM to

store program instructions and data. A key parameter of Flash memory is its endurance or the

number of times it can be erased or reprogrammed. Depending on the technology used, flash

endurance can be either 100 or 300,000 program/erase cycles.

RAM (Random Access Memory)

During in the execution of a program, data have to be saved for later use. Data are usually

stored in RAM.

EEPROM (Electrically Erasable Programmable Read Only Memory)

There is another way to store data in a microcontroller: EEPROM is used to store data that

must be saved through a power down cycle.

CPU (Central Processing Unit)

It is the brain of the system that processes all data and their travel along the bus. For example,

in order to execute a program, the CPU will read the first instruction from program memory.

This instruction is decoded by the CPU and executed. At the completion of the execution of

the instruction, the next instruction is fetched from memory and is executed. This procedure is

repeated until the end of the program (or an endless loop) is found.

Figure 2. Typical Microcontroller Block Organization

TIMERS

The timer or timing system makes it possible to measure and time external and internal

events. The power of the timers varies greatly between different MCUs.

I / O (INPUT / OUTPUT) PORTS

Most microcontrollers have several digital I/O ports that are used to drive a LED or get a key-

board input. Usually, a port consists of eight or less bits, usually programmable as either input

or output bits.

CENTRAL

PROCESSING

UNIT

RAM

EEPROM

DATA

MEMORY

ROM

PROGRAM

MEMORY

INPUT

OUTPUT

TIMING

SYSTEM

BUS

PERIPHERAL

SYSTEMS

VR02101B

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