- In 1981, Intel introduced an 8-bit microprocessor called the 8051. It is the most popular and general-purpose microcontroller. 8051 is an 8-bit microcontroller thus it has an 8-bit word length to fetch, execute, process the programs as it has an 8 bit CPU.
- It has an 8-bit data bus and a 16-bit data bus. This 16-bit address bus can address 64k byte code memory space.
- It is designed to have 40 pins dual linkage package with 4kb of ROM storage and 128 bytes of RAM storage and 2 16 bit timers.
- It consists of four parallel 8 bit ports which are programmable as well as addressable as per the requirement.
- For example, a crystal oscillator is integrated with the microcontroller having a crystal frequency of 12 MHz.
Let us now discuss the architecture of the 8051 microcontrollers.
- The 8051 microcontroller is an 8-bit microcontroller. It can read, write and process 8 bits of data.
- There is a bunch of manufacturers like Atmel, NXP, Texas instrument who manufacture their version of 8051 microcontrollers.
- The internal architecture of the 8051 microcontroller remains more or less the same. The below diagram shows the block diagram with the component of 8051 microcontrollers.
- CPU- It is the main part of the microcontroller mainly consist of ALU and CU. ALU stands for the arithmetic logic unit and CU stand for control unit which is responsible for the timing of the communication process between CPU and other peripherals component. CPU can perform arithmetic and logical operation on the data such as addition, subtraction, multiplication, and division. This is an 8 bit CPU i.e it can perform on 2 8bit data.
- Program memory is also known as code memory is a read-only memory used to store the CPU instructions.
- The data memory is also known as RAM (Random Access Memory) is used to store the value variable temporary data and immediate result for the proper operation of the microcontroller. RAM is a volatile memory and generally organized as a register and user-accessible memory location
- I/O Port- I/O Ports means input-output ports provide the microcontroller a physical connection with the outside world. These ports can be configured as input ports or output ports. Input port provides a gateway for passing data from the outside world to the microcontroller with help of the sensor and the output port allows the microcontroller to control external devices like motor, LED, etc.
- Oscillator- The oscillator is used to generate the clock signal. The clock signal allows the operation inside the microcontroller and other parts to be synchronous. The clock generates is an integrated part of the microcontroller architecture and the user has to provide additional timing circuitry in the form of crystal.
- Timers- Timer hardware is used to generate delay and the same hardware can be used to count external events on T0 and T1 pins
- Serial port- This serial port is used for serial communication between the microcontroller and other serial devices.
- Interrupt control block- This block is used to control external and internal interrupt in microcontrollers.
This all component interfaces together through a system bus.
