Department of Computer Scien

ce and Information Engineering

National Cheng Kung University, TAIWAN

I/O HANEL

PROGRAMMING

Port 0

‰It can be used for input or output, each pin must be connected externally to a 10K ohm pull-up resistor

¾This is due to the fact that P0 is an open drain, unlike P1, P2, and P3

ƒOpen drain

is a term used for MOS chips in the

same way that open coll

ector is used for TTL

chips

Vcc P0.0P0.1P0.2P0.3P0.4P0.5P0.6P0.7

10 K

8051

Port 0

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
P0.X