IC of 8051 microcntroller are 40 pins with DIP(dual in package).32 pins of controller used as I/O pins to read and write data from peripheral device as well as to connect external device with microcontroller.there are four ports(P0,P1,P2 & P3) in micro controller.each ports contain 8pins within.each port work as I/O ports.upon reset configure all port work as input ports.
PORT 0 (P0.0 TO P0.7).
- Pin No :32 to 39.
- work as input or output port.
- also provide 8 bit data (AD0-AD7).
- it also give lower byte of address (A0-A7) with PORT 2.
- connect pull-up register with port 0 with it.
- to make this port as input we have to write 1 to all pins.for output write 0 to all pins of this port.
PORT 1(P1.0 TO P1.7):
- Pin No :1 to 8
- it work as input or output.
- its do not need to connect pull up register because internally connected pull up register.
- port1 is by default input port to make it as output port write 0 to all pins of it.
PORT 2(P2.0 TO P2.7):
- Pin no:21 to 28.
- Work as input or output port.
- also provide higher byte of address (A8-A15) with port0.
PORT 3(P3.0 TO P3.7):
- Pin no:10 to 17.
- work as input or output.
- also each pin have different function which shown in next table.
how to make any port as input/output port?
port 0 as input port.
MOV P0,#0FFHport0 as output port.
MOV P0,00H
1 comments:
how to initiate port 3 as an input port ?
acutely there is push switch connecting to p3.2 and i need call function when the user pressed the push switch >>> not counter and not timer... just call a function ( do special thing) when push witch pressed
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