Department of Computer Scien

ce and Information Engineering

National Cheng Kung University, TAIWAN

I/O HANEL

PROGRAMMINGI/O Port Pins

‰The four 8-bit I/O ports P0, P1, P2 and P3 each uses 8 pins‰All the ports upon RESET are configured as input, ready to be used as input ports

¾When the first 0 is written to a port, it becomes an output¾To reconfigure it as an input, a 1 must be sent to the port

ƒTo use any of these ports as an input port, it must be programmed

P1.0P1.1P1.2P1.3P1.4P1.5P1.6P1.7RST(RXD)P3.0(TXD)P3.1(INT0)P3.^2 (I^3 NT1)P3.(T0)P3.4(T1)P3.5(WR)P3.6(RD)P3.7XTAL2XTAL1GND

VccP0.0(AD0)P0.1(AD1)P0.2(AD2)P0.3(AD3)P0.4(AD4)P0.5(AD5)P0.6(AD6)P0.7(AD7)-EA/VPPALE/PROG-PSENP2.7(A15)P2.6(A14)P2.5(A13)P2.4(A12)P2.3(A11)P2.2(A10)P2.1(A9)P2.0(A8)

(^1234567891011121314151617181920)
(^40393837363534333280513130) (8031) 292827262524232221