实验用的ADC0809逐次逼近A/D转换器是八位A/D转换器。每采集一次一般需100us。本程序是用延时查询方式读入A/D转换结果。也可以用中断方式读入结果，在中断方式下，A/D转换结束后会自动产生EOC信号，将其与CPU的外部中断相接。-Experiment with the ADC0809 successive approximation A/D converter is eight A/D converter. Each collection time normally takes 100us. This program is read into the delay ways to search for A/D conversion results. Interrupt can be read with the result, in the interrupt mode, A/D conversion will be automatically generated after the EOC signal to the CPU s external interrupt phase.