DATA_ACQUISITION_SYSTEM_Ⅱ

Published:2009/7/10 3:08:00 Author:May | From:SeekIC

In this circuit, an HA-4900 series comparator is used in conjunction with a D/A converter to form a simple, versatile, multichannel analog input for a data acquisition system. The processor first sends an address to the D/A, then the processor reads the digital word generated by the comparator outputs. lb perform a simple comparison, the processor sets the D/A to a given reference level, then examines one or more comparator outputs to determine if the inputs are above or below the reference. A window comparison consists of two such cycles with two reference levels set by the D/A. 0ne way to digitize the inputs would be for the processor to increment the D/A in steps. The DiA address, as each comparator switches, is the digitized level of the input. While stairstepping, the D/A is slower than successive approximation; all chan-nels are digitized during one staircase ramp.



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