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为了提高单片机检测控制系统的抗干扰能力,有效的方法是进行光电隔离.对开关量信号的光电隔离是很容易的,但对模拟量的隔离要相对困难一些.采用数字光电隔离法实现模拟量隔离,其优点是不存在非线性问题,且成本低.数字光电隔离电路如图1所示.该电路含16路8位A/D转换、双路8位D/A转换,通过一片8255实现与单片机8031硬件接口.其中PB口作A/D数字隔离后的信号输入,PA_(4～7)作16路模拟输入的模拟开关控制.PA_3作A/D转换的起动.PC口作D/A的数字输出,PA_0、PA_1作两片D/A的片选控制和第一级寄存器写入,PA_2同时控制两片D/A的第二级寄存器写入.
In order to improve the anti-jamming ability of the single-chip detection and control system, the effective method is to conduct optical isolation .On the photoelectric isolation of the switch signal is very easy, but it is relatively difficult for analog isolation.Make use of digital photoelectric isolation method to achieve analog Isolation, the advantage of non-existent non-linear problems, and low cost digital optoelectronic isolation circuit shown in Figure 1. The circuit contains 16 8-bit A / D conversion, dual 8-bit D / A conversion, achieved through a piece of 8255 And 8031 hardware interface.Among which PB port for A / D digital isolated signal input, PA_ (4 ~ 7) for analog input control of 16 analog switches.PA_3 for A / D conversion start.PC mouth for D / A digital output, PA_0, PA_1 for two D / A chip select control and first-level register write, PA_2 at the same time control two D / A second-level register write.