AT89C2051 Integrated Circuit (IC)

AT89C2051 Features:

• 2K bytes of Reprogrammable Flash Memory (PEROM) - Endurance: 1,000 Write/Erase Cycles
• 2.7V to 6V operating range
• 128 x 8 bytes of RAM
• 15 Programmable I/O lines (Ports 1.0-1.7 & Ports 3.0-3.5 & 3.7)

Pin Configuration:

• VCC (Pin 20) – Supply Voltage
• GND (Pin 10) – GroundPort 1 (Pins 12 – 19) – 8 Bit bi-directional I/O port
• Port 3 (Pins 2-3,6-9, 11) - Seven bi-directional I/O pins with internal pull-ups
• RST (Pin 1) - Reset input  
• XTAL1 (Pin 5) - Input to the inverting oscillator amplifier and input to the internal clock operating circuit. 
• XTAL2 (Pin 4) - Output from the inverting oscillator amplifier. 
• Port pins P1.2 to P1.7 provide internal pull-ups 
• P1.0 and P1.1 require external pull-ups
• P1.0 and P1.1 also serve as the positive input (AIN0) and the negative input (AIN1)
• P3.6 is hard-wired as an input to the output of the on-chip comparator and is not accessible as a general-purpose I/O pin. 

Block Diagram:

Oscillator Characteristics:

    The XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which can be configured for use as an on-chip oscillator

Note: C1, C2 = 10-30 pF ± 10 pF for Crystals

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Introduction to Atmel 8051

Microcontroller 

VS 

Microprocessor

Microcontroller Unit(MCU)

      A microcontroller is a self-contained system with peripherals, memory and a processor that can be used as an embedded system. Most programmable microcontrollers that are used today are embedded in other consumer products or machinery including phones, peripherals, automobiles and household appliances for computer systems. Due to that, another name for a microcontroller is "embedded controller." They are designed to perform specific tasks. Specific means application where the relationship of input and output is defined. 

Microprocessor

      A microprocessor incorporates the functions of a CPU on a single integrated circuit or a few integrated circuits. They are designed to perform arithmetic and logic operations that make use of data on the chip. General purpose microprocessors in PCs are used for multimedia display, computation, text editing and communication. Several microprocessors are part of embedded systems.

History

      The Center of computer is CPU. Initial days, the CPU was built with Vacuum Tubes, Transistors, IC etc.

      In the year 1969, Intel company put the entire CPU inside a single IC. This IC is called Microprocessor.

      Microcomputer is built using this Microprocessor as CPU, RAM, ROM, I/O etc.

      The logic part of microcomputer is put inside an IC and called Microcontroller.

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