8051 microcontroller tutorial - an introduction to 8051 family

The most commonly used set of microcontrollers belong to 8051 Family. 8051 Microcontrollers continue to remain a preferred choice for a vast community of hobbyists and professionals. Through 8051, the world became witness to the most revolutionary set of microcontrollers.








there  many 8-bit microcontrollers available in market and they have different architecture and features-
􀂾 Motorola’s 6811
􀂾 Intel’s 8051
􀂾 Zilog’s Z8
􀂾 Microchip’s PIC

introduction to 8051:

In 1971, intel coprotration introduce an 8-bit mircrocontroller called 8051. it had 128 bytes of RAM, 4K bytes of on-chip ROM, two timmer, one serial port and four ports (each 8 bit wide) all on a single chip. b bit microcontroller means it can process 8 bit wide data. data large than 8 bit has to be broken in to 8-bit pieces. MCS-51 is the original member of 8051 family and intel refers it as MCS-51.

8051 family:

mainly there are 3 microcontroller in 8051

• 8051
• 8052
• 8031

Important:

you cannot see 8051 on any micorocontroller, they  named like 'AT89c51', 'DS5000', 'DS89c420'. this is because intel give rights to other compnaies to produce 8051 family microcontroller with a condition that they cannot change their archi techaure.so there are many version of 8051 with different memory, different type of ROM, numbers of ports etc.   but all the microcontroller are compatibile to each other even  they made by different companies.

8051:

it is main member and mostly used in low memory projects because it have following specifications

• 4k byte of ROM
• 128 byte of RAM
• 4 input/output port
• 2 timer
• 6 interrupt 
• one serial port

8052:

it is similar to 8051 but it have some extra RAM and ROM then 8051, other specifications are-

• 8 k byte ROM
• 256 byte of RAM
• 4 input/ output port
• 3 timer
• one serial port

8031: ROM less 8051

This microcontroller has all the features of 8051 except for it to be ROM-less. An external ROM that can be as large as 64 K bytes should be programmed and added to this chip for execution. The disadvantage of adding external ROM is that 2 ports (out of the 4 ports) are used. Hence, only 2 ports are left for I/O operations which can also be added externally if required for execution.



















The 8051 family has the largest number of diversified (multiple source) suppliers
􀂃 Intel (original)
􀂃 Atmel
􀂃 Philips/Signetics
􀂃 AMD
􀂃 Infineon (formerly Siemens)
􀂃 Matra
􀂃 Dallas Semiconductor/Maxim

In  second tutorial we will talk about Registers and some instructions ( ADD , MOV ) and how to use them.