RST 20 VCC (RXD) P3. 0 P1.7 (TXD) P3. 1 P1.6 ⅩTAL2 P1.5 ⅩTAL1 AT89C2051 P1.4 (INTO)P3. 2 P1.3 (INT1)P3.3 P1.2 (TO)P3.4 P1.1(AIN1) (T1)P3.5 P1.O(AINO) GND 10 P3.7 图10.1AT89C205的结构框图RST (RXD) P3.0 (TXD) P3.1 XTAL2 XTAL1 (INT0)P3.2 (INT1)P3.3 (T0)P3.4 (T1)P3.5 GND VCC P1.7 P1.6 P1.5 P1.4 P1.3 P1.2 P1.1(AIN1) P1.0(AIN0) P3.7 AT89C2051 1 10 11 20 图10.1 AT89C2051的结构框图