Microcomputer-Based Synchronous Multichannel Data Acquisition System

Most of the multichannel data acquisition systems invariably use a sequential data conversion method. Thus, the sampling instants of the analog signals are dispersed in time. However, synchronous sampling is desirable when the data are required for system indentification studies, or when fast data conversion of a large number of analog channels is involved. A cost-effective technique is proposed here for a microcomputer-based 8-channel synchronous data acquisition system. The software routine for complete data conversion and storing the values in RAM takes only 93 /s=u/s of CPU time, when used with a single-board microcomputer SDK-85. As the A/D converters (ADC's) are operated in a memory mapped mode, the system can be expanded almost indefinitely. The circuit can handle ADC's of 12-bit resolution as well.