一款带模数转换的单片机设计

摘要

With the size reduction in electronic system,the requirement of more functions integrated into a single chip is produced.So analog to digital converter combining with microcontroller will be used in more applications,such as reducing the size and weight.A way to embed a 12 bit SAR A/D converter into MCS5 1 microcontroller is discussed.The difficulties are made from the Microcontroller's working speed and CMOS process precision.The design must be fixable if 12 bit precision needs to be achieved. A/D control circuit is embedded in SFR,and the fixed code is transferred from flash by means of reset timing.Test result shows that 12 bit A/D converter can be embedded into microcontroller and get the aimed precision.%随着电路系统体积的不断缩小，应用上希望在单个芯片上嵌入更多的电路功能。而模数转换器和单片机的组合，能够从相当程度上满足应用需求，并有效缩小电路板的体积和重量。研究如何在MCS51单片机的基础上，嵌入12位SAR型模数转换器。嵌入的难点在于单片机本身工作在较高的频率下，自然会对A／D的转换精度造成一定影响，并且CMOS的工艺精度只能达到10位精度的匹配效果，要想达到12位A／D，必须进行修调设计。通过对单片机内部的研究，提出了从SFR区嵌入A／D控制功能，并利用上电复位的时间，从flash加载修调码至A／D转换器。结果显示，12位模数转换器能够有效嵌入单片机并达到预计精度。