Introduction To Micro Controller

The Intel 8031/8051/8751 is a stand-alone, high performance single-chip computer fabricated with Intel's highly reliable + 5 Volt, depletion load, N-channel, silicon gate MOS technology and packed in a 40 pin. It provides the hardware features, architectural enhancements and new instructions that are necessary to make it a powerful and cost effective controller for applications requiring up to 64 K bites of Program memory and/or up to 64 bytes of data storage.

The 8051/8751 contains a non-volatile 4K x 8 read-only program memory; a volatile 128 x 8 read/write data memory; 32 I/O lines; two 16 bit timer/counters; a five source, two-priority-level, nested interrupt structure; a serial I/O port for either multi process communication; i/O expansion or full duplex UART and on chip oscillator and clock circuits. The 8031 is identical, except that it takes for program memory. For systems that require extra capability, 8051 can be expanded using standard TTL compatible memories and bytes oriented MCS-80 and MCS-85 peripherals.

The 8051 microcomputer, like its 8048 processor that is efficient both as a controller and as an arithmetic processor. The 8051 has extensive facilities for binary and BCD arithmetic and excels in bit-handling capabilities. Efficient use of program memory results from an instruction set consisting of 44% of one byte 41% of two byte, 15% three byte instructions.

The 8051 is a stand - alone high - performance single chip computer intended for use in sophisticated real-time applications such as instrumentation, industrial control and intelligent computer peripherals. It provides the hardware features, architectural enhancements and new instructions that make it a powerful and cost effective controller for applications requiring up to 64 K bytes of program memory and/or up to 64 K bytes of data storage.

The 8031 is a control-oriented CPU without on-chip program memory. It can address 64Kbytes of external program memory in addition to 64K-bytes of External Data Memory. For systems requiring extra capability, each member of the 8051 family can be expanded using standard memories. The 8051 is on 8031 with the lower 4K bytes of program memory filled with on-chip mask programmable ROM while the 8751 has 4K-bytes of UV light erasable/electrically-programmable ROM.

The 8051 CPU manipulates operands in four memory spaces. These are the 64 K-bytes program memory, 384-byte Internal data memory and 16-bit program counter spaces. The internal data memory address space is further divided into the 256 byte Internal Data RAM and 128 byte special Function Register (SFR) address spaces Four Register Banks (each with eight registers), 128 addressable bits, and the stock reside in the Internal Data RAM. The stock depth is limited only by the available Internal Data RAM and its location is determined by the 8 -bit stack pointer. All Registers except the program counter and the four 8 Register Bank reside in the special function Register address space. These memory mapped registers include arithmetic registers, pointers 1/O ports, interrupt system registers, timers and special port. 128 bit locations in the SFR address space are addressable as bits. The 8051 contains 128 bytes of Internal Data RAM and 20 SFRs.

The 8051 provides a non-paged program Memory address space to accommodate relocatable code. Conditional branches are performed relative to the program counter. The register indirect jump permits branching relative to a 16 bit base register with an offset provided by an 8-bit index register. Sixteen-bit jumps and calls permit branching to any location in the contiguous 64 K program memory address space.

The 8051 is classified as an 8-bit machine since the internal ROM, RAM, SFRs, Arithmetic/Logic unit and external data has are each 8-bit wide. The 8051 performs operations on bit, nibble, byte and double-byte data types. The 8051 has extensive qualities for byte transfer, logic and integer arithmetic operations. It excels at bit handling since data transfer, logic and conditional branch operations can be performed directly on Boolean variables.By the use of micro controller 8051 we can control the voting by using number of voting units and a master unit.