A current i at Li produces an open circuit voltage u,at L2s dyal

Let us add and subtract on the right side of I2 we have

9.1 I/O接口扩展概述 9.1.1 扩展的I/O接口功能 9.1.2 I/O端口的编址 9.1.3 I/O数据的传送方式 9.1.4 I/O接口电路 9.2 AT89S52扩展I/O接口芯片82C55的设计 9.2.1 82C55芯片简介 9.2.2 工作方式选择控制字及端口PC置位/复位控制字 9.2.3 82C55的3种工作方式 9.2.4 单片机扩展82C55的接口设计 9.2.5 AT89S52扩展82C55的应用举例 9.3 利用74LSTTL电路扩展并行I/O口 9.4 用AT89S52单片机的串行口扩展并行口 9.4.1 用74LS165扩展并行输入口 9.4.2 用74LS164扩展并行输出口 9.5 用I/O口控制的声音报警接口 9.5.1 蜂鸣音报警接口 9.5.2 音乐报警接口

Frequency characteristics(Xi, xc,x,z, y, o vs o Z=R+A=R+(L+Xc)=R+ilo I

练习 1解方程z-2iz-5=0. 2求z=(1+i)的值 3证明三角形的内角和等于π

We assume=Im cos(t+a)i=Im cos(ot+B) The phase angle by which the voltage leads

Let us assume a solution i(t=Ae, where a and S, are constant to be determined

Ohm's law states that voltage across many types of conducting materials is directly proportional to the current flowing through the material. U= Ri or R= i R--resis tance()( linear resistor) The resistor is a passive element that cannot deliver power or store energy

一、选择题(共20p每小题1p)(请直接圈出你的选择,例如:(A) 1、图示电路,求i

1.解 1-1说明图(a),(b)中,(1)u,i的参考方向是否关联?(2)乘积表示 什么功率?(3)如果在图(a)中u>0,i0,i>0,元件实际发 出还是吸收功率?