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Monday, 23 March 2015

Introduction to Microcontrollers and AVR





Topic: What is a Microcontroller(µC) and how it differs from Microprocessors!!!

MICROPROCESSORS :

Microprocessor is an IC which has only the CPU inside them i.e. only the processing powers. There are no Ram, Rom or other peripherals on chip. So to make a microprocessor functional, the user  has to add them externally. That is why we can easily add/change Ram or hard disk without bothering about the microprocessor such as Intel’s Pentium 1,2,3,4, core 2 duo, i3, i5 etc. The processing speed of MPUs now a days are above 1Ghz.


MICROCONTROLLERS : 

It has a CPU, in addition with a fixed amount of RAM, ROM and other peripherals all embedded on a single chip. At times it is also termed as a mini computer or a computer on a single chip. The processing speed is in the range of Mhz, like AVR microcontrollers mostly run with a 12mhz/16mhz on board crystal oscillator which serves as the processing speed or simply the heart beat of the system.

**In brief, Microprocessor Units (MPU) are much faster than Microcontroller Unit (MCU), but MCUs are way too cheap. Although they can't be compared with price and neither can they replace each other's existence. 

AVR Microcontrollers






  • Basically, AVR is the name of the architecture of this microcontroller series under ATMEL corporation.

  • There are different ICs like Atmega8, Atmega16, Atmega32 etc., all following the same architecture but differing in many aspects viz.,

  1. Ram
  2. Rom
  3. EEPROM
  4. Flash Memory
  5. GPIO
The differences can be spotted right from their datasheets (links provided below).


atmega32.pdf

Now you must be confused about what Microcontroller should you use for your work?

Different MCUs are available with different specifications as said above. Lets discuss some of them:

 GPIO:  These are the general purpose I/O pins of the MCU. The more the number of I/O pins, the more number of Input Devices (switches,sensors) and Output Devices (leds, motors,relays) you can interface with the system.

Flash Memory : It is the space inside the unit where your program gets stored; the more the space i.e., larger Flash Memory, the more complex and large program you can store.

EEPROM :   The MCU can store some data in its RAM, but as RAM is volatile, the memory gets deleted after Power Off or resetting the device. But sometimes some data (like passwords) needs to be retained in the system even after power off. As the EEPROM is non-volatile, any data (of size within the max limit of the EEPROM) can be stored inside the EEPROM memory to keep it safe during any interrupts in the power of  the device. 








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