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Chapter: Microprocessor and Microcontroller - 8051 Micro Controller

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I/O Ports - 8051 Micro Controller

The 8051 contains four I/O ports All four ports are bidirectional

I/O Ports

 

ü The 8051 contains four I/O ports

ü All four ports are bidirectional

 

ü Each port has SFR (Special Function Registers P0 through P3) which works like a latch, an output driver and an input buffer

 

ü Both output driver and input buffer of Port 0 and output driver of Port 2 are used for accessing external memory

 

ü Accessing external memory works like this

 

1.     Port 0 outputs the low byte of external memory address (which is time- multiplexed with the byte being written or read)

 

2.     Port 2 outputs the high byte (only needed when the address is 16 bits wide)

ü Port 3 pins are multifunctional

ü The alternate functions are activated with the 1 written in the corresponding bit in the port SFR

 

Table 4.3 Alternate Functions of Port 3 pins


 


Serial Communication

 

Some of the external I/0 devices receive only the serial data. Normally serial communication is used in the Multi-Processor environment.8051 has two pins for serial communication.

 

ü SID- Serial Input data.

ü SOD-Serial Output data.


Interrupt Structure

 

ü The 8051 provides 4 interrupt sources

ü Two external interrupts

ü Two timer interrupts


Port Structure


ü The 8051 contains four I/O ports

ü All four ports are bidirectional


ü Each port has SFR (Special Function Registers P0 through P3) which works like a latch, an output driver and an input buffer


ü Both output driver and input buffer of Port 0 and output driver of Port 2 are used for accessing external memory


ü Accessing external memory works like this


ü Port 0 outputs the low byte of external memory address (which is time- multiplexed with the byte being written or read)


ü Port 2 outputs the high byte (only needed when the address is 16 bits wide)

ü Port 3 pins are multifunctional


Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail


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