8051: Unique Features

The 8051 microcontroller is generic part number actually includes a whole family of microcontrollers that have numbers ranging from 8031 to 8751 and are available in N-channel Metal Oxide Silicon(NMOS) and Complimentary Metal Oxide Silicon(CMOS) constructed in a variety of package types. The unique features of 8051 are;

♂Internal RAM and ROM
♂I/O ports with programmable pins
♂Timers and counters
♂Serial data communication
The block diagram shows usual CPU components- program counter, ALU, working registers, and clock circuits.
The 8051 architecture consists of these specific features;
●8-bit CPU registers A(the accumulator) and B
●16-bit program counter(PC)and data pointer(DPTR)
●8-bit status word
●Internal ROM or EPROM(for 8751) of 0(for 8031) to 4K(for 8051)
●Internal RAM of 128 bytes:
◆Four register banks each containing 8 registers
◆16-bytes, which may be addressed at the level
◆80-bytes general purpose data memory
◆32 I/O pins arranged as 4 eight-bit ports:P0 to P3
◆Two 16-bit timer/counters: T0 and T1
◆Full duplex serial data receiver/transmitter
◆Control registers: TCON, TMOD, SCON, IP and IE
◆Two external and 3 internal interrupt sources
◆ Oscillator and clock circuits

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8051 Simple Programs

Sum of 8-bit Numbers Stored in Memory Here we will discuss about 8051 programs but we can't discuss about all of the 8051 instructions. For programming 8051 we should know about assembler directives as well as instruction set. Click here to download Atmel c51 user guide that will discuss about 8051(c51 family microcontroller) instruction set, assembler directives, c51 cross assembler from Atmel. Program ORG 00H MOV R0,#50H ; get memory location in memory pointer R0 MOV R1,#51H ; get memory location on memory pointer register R1 MOV A,@R0 ; get content of memory location 50H to accumulator ADD A,@R1 ; add content of A with content of memory location 51H and store result in A MOV R0,#52H ; get 52H to memory pointer R0 MOV@R0,A ; copy content of A to memory location 52H END Add 16-bit Numbers ...

ATMEGA-32 Pin-out Diagram

Overview The Atmel®AVR®ATmega32 is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega32 achieves throughputs approaching 1 MIPS per MHz allowing the system designer to optimize power consumption versus processing speed. AVR spin-out diagrams Block diagram:- The Atmel®AVR®AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers. The ATmega32 provides the following features: 32Kbytes of In-System Programmable Flash Program memory with Read-While-Write capabilities, 1024bytes EEPROM, 2Kbyte SRAM, 32 general purpose I/O ...

Even and Odd Memory Banks

The 8086 microprocessor uses a 20-bit address to access memory. With 20-bit address the processor can generate 2 20 = 1 Mega address. The basic memory word size of the memories used in the 8086 system is 8-bit or 1-byte (i.e., in one memory location an 8-bit binary information can be stored). Hence, the physical memory space of the 8086 is 1Mb (1 Mega-byte). For the programmer, the 8086 memory address space is a sequence of one mega-byte in which one location stores an 8-bit binary code/data and two consecutive locations store 16-bit binary code/data. But physically (i.e., in the hardware), the 1Mb memory space is divided into two banks of 512kb (512kb + 512kb = 1Mb). The two memory banks are called Even (or Lower) bank and Odd (or Upper) bank. The organization of even and odd memory banks in the 8086-based system is shown in Figure. The 8086-based system will have two sets of memory IC's. One set for even bank and another set for odd bank. The data lines D 0 -D 7 are conne...

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