Data Range
The data range of the A/D converter is determined by
A/D Ref Input+ and A/D Ref Input-. A/D Ref Input- sets the bottom of the data range. Any input voltage that is less than or equal to the A/D Ref Input- will be read as a zero. A/D Ref Input+ sets the top of the data range. Any input voltage that is greater than or equal to the A/D Ref Input+ will be read as a 1023 (3FFh). The data range is as follows:
Data Range = (A/D Ref Input-) to (A/D Ref Input+)
Data Range = 0 to 1023 Data Range = 0 to 3FFh
Figure 4.1 shows the Data Range and A/D Ref Inputs relationship.
Figure 4.1 - A/D Converter Data Range
Converting Data
The data read from the 485SDA10 A/D converter is directly related to the A/D input channel and the reference range (discussed in previous sections). The 485SDA10 has a 10-bit A/D converter. A 10-bit A/D has 1024 possible output values, 0 to 1023 (0 to 3FFh). These 1024 output values are divided into equal steps over the reference range. The size of each step can be computed as follows:
Step size = (Reference Range) / 1023
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