Department of Computer Scien

ce and Information Engineering

National Cheng Kung University, TAIWAN

PIN HANEL

DESCRIPTION XTAL1 and

XTAL2

‰The 8051 has an on-chip oscillator but requires an external clock to run it

¾A quartz crystal oscillator is connected to inputs XTAL1 (pin19) and XTAL2 (pin18)

ƒThe quartz crystal oscillator also needs two capacitors of 30 pF value

XTAL2 XTAL1 GND

C2 30pFC1 30pF

P1.0P1.1P1.2P1.3P1.4P1.5P1.6P1.7RST(RXD)P3.0(TXD)P3.1(INT0)P3.2(INT1)P3.3(T0)P3.4(T1)P3.5(WR)P3.6(RD)P3.7XTAL2XTAL1GND

(^8051) (8031)
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)
4039383736353433323130292827262524232221