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8051 BoardsMicro controller Boards

Learn 8051, PIC, AVR On the Go-Part1


This article is originally intended to learn AT89S51, PIC16F877A, and ATMEGA16 at the same time. The learning process requires no prior knowledge but follow the article blindly. Here the method is so simplified to learn the three microcontrollers as easy as possible.


A Microcontroller needs three external components to be connected at some special pins. They are Power supply, Oscillator and Reset circuitry. Even though several microcontrollers has internal oscillator, this is not the case that we are going to deal. The following table specifies the basic components needed,


S.No Component Name AT89S51 PIC16F877A ATMEGA16
1 Power Supply +5V, GND +5V, GND +5V, GND
2 Crystal Oscillator(Popular) 4-33Mhz(11.0592) 1-20Mhz(10MHz) 1-16Mhz(16MHz)
3 Reset-Reset MCU VCC GND GND
5 Special Pins EA&PSEN-VCC


*Refer the Test Circuit for PIN details


The supply +5V need to be given on the VDD or VCC pins of microcontroller. This can be derived from an external power supply circuit or via USB connector. The USB port of PC can supply 5V, 100mA, so it’s enough to operate a microcontroller.


Oscillator row specifies the possible range but the most popularly used crystals are 11.0592MHz for 8051, 10MHz for PIC and 16MHz for ATMEGA.


The Reset pin when supplied with Reset MCU (Row 3) will reset the microcontroller to its initial state or it will hold the microcontroller in reset as long as it is supplied by Reset MCU. For normal execution the reset pin should be configured as per (row 4) Reset-EXE mode i.e. straight opposite to reset state.


There are some Special Pins in 8051, EA and PSEN. EA (external access) is tied to VCC and the pin PSEN is tied with VCC or left open for normal execution.


Sample Schematic Circuit for 8051


Sample Schematic Circuit for PIC16F877A


Sample Schematic Circuit for AT MEGA AVR



Tags : 80518051 tutorialAVR On the Go-Part1avr tutorialPICpic tutorial

The author jeevarajan