which port suitable for connecting an lcd

[prasadideas]

among the 4 ports of the microcontroller at89s52, which port is best suitable for connecting an lcd,ttl logic devices,keypad..etc..
plz tell me i suffer a lot of problem with tihs............................

 

[nandhu015]

You can use any port for anything. Only thing to be noticed is port3 is having interrupts and uart pins.

 

[dojo]

Port 0
The P0 port is characterized by two functions. If external memory is used then the lower address byte (addresses A0-A7) is applied on it. Otherwise, all bits of this port are configured as inputs/outputs.

Port 1
P1 is a true I/O port, because it doesn't have any alternative functions as is the case with P0, but can be cofigured as general I/O only. It has a pull-up resistor built-in and is completely compatible with TTL circuits.

Port 2
P2 acts similarly to P0 when external memory is used. Pins of this port occupy addresses intended for external memory chip. This time it is about the higher address byte with addresses A8-A15. When no memory is added, this port can be used as a general input/output port showing features similar to P1.

Port 3
All port pins can be used as general I/O, but they also have an alternative function. In order to use these alternative functions, a logic one (1) must be applied to appropriate bit of the P3 register. In tems of hardware, this port is similar to P0, with the difference that its pins have a pull-up resistor built-in.

 

[gccute]

any port is good but with port 0 u have to connent a pull resistor ship of 10 k..

it is not required with p1,p2,p3....

 

[dojo]

Yes port0 does not have internal pullups so you can plan your circuit according to this for interfacing lcd,ttl logic devices,keypad..etc..