8051 Microcontroller

The 8051 is a Harvard architecture, single chip microcontroller (µC) series which was developed by Intel in 1980 for use in embedded systems.Intel's original versions were popular in the 1980s and early 1990s. While Intel no longer manufactures the MCS-51, binary compatible derivatives remain popular today. In addition to these physical devices, several companies also offer MCS-51 derivatives as IP cores for use in FPGAs or ASICs designs.

Intel's original MCS-51 family was developed using NMOS technology, but later versions, identified by a letter C in their name (e.g., 80C51) used CMOStechnology and were less power-hungry than their NMOS predecessors. This made them more suitable for battery-powered 

devices.

Important features and applications

i8051 microarchitecture.

The 8051 architecture provides many functions (CPU, RAM, ROM, I/O, interrupt logic, timer, etc.) in a single package

• 8-bit ALU, Accumulator and 8-bit Registers; hence it is an 8-bit microcontroller
• 8-bit data bus – It can access 8 bits of data in one operation
• 16-bit address bus – It can access 2¹⁶ memory locations – 64 KB (65536 locations) each of RAM and ROM
• On-chip RAM – 128 bytes (data memory)
• On-chip ROM – 4 kByte (program memory)
• Four byte bi-directional input/output port
• UART (serial port)
• Two 16-bit Counter/timers
• Two-level interrupt priority
• Power saving mode (on some derivatives)

One particularly useful feature of the 8051 core was the inclusion of a boolean processing engine which allows bit-level boolean logic operations to be carried out directly and efficiently on select internal registers and select RAM locations. This advantageous feature helped cement the 8051's popularity in industrial control applications because it reduced code size by as much as 30%. Another valued feature is the including of four bank selectable working register sets which greatly reduce the amount of time required to complete an interrupt service routine. With a single instruction the 8051 can switch register banks as opposed to the time consuming task of transferring the critical registers to the stack or designated RAM locations. These registers also allowed the 8051 to quickly perform a context switch which is essential for time sensitive real-time applications.

Basic Working Circuit For 8051

click here to see 8051 datasheet