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8位单板微型机常常配置一个并行接口片供用户使用,如8255,R6522等。若将其 B、C口用作控制,A 口用作输入输出数据,则仅有8位数据线。假如控制和检测要求用8个、16个或24个 LED 发光二极管显示不同的工作状态,而且要求任一 LED 灯点亮不受先前或以后各种因素的影响,具有程序设计的独立性、方便性。这一问题表面看来不难,其实若不巧妙解决许多矛盾,简直无法实现。本文以洛克韦尔公司的 AIM 65机用于故障检测为例给出一种实用逻辑,原则上适用于任何其它微型机,也适用于多路手动控制输出,因而具有典型性。
8-bit single board microcomputer is often configured with a parallel interface for users to use, such as 8255, R6522 and so on. If its B, C port for control, A port as input and output data, only 8-bit data line. If the control and testing requirements of the use of 8, 16 or 24 LED light-emitting diodes show different working conditions, and require any LED lights from previous or future various factors, with the independence of programming, convenience Sex. It seems easy to see this issue on its face. Actually, many contradictions can not be solved without clever solution. This article is based on the Rockwell AIM 65 machine for fault detection as an example to give a practical logic, in principle, for any other micro-computer, but also for multiple manual control output, which is typical.