Appendix E. Manual Calibration; A/D Calibration - Advantech MIC-3716 Manual

Appendix E. Manual Calibration

E.1 A/D Calibration
Regular and proper calibration procedures ensure the maximum
possible accuracy. It is easy to complete the A/D calibration procedure
automatically (i.e. through software calibration) by executing the A/D
calibration program AutoCali.EXE. Therefore, it is not necessary to
adjust the hardware settings of the MIC-3716. However, the following
calibration steps are also provided for your reference in case manual
calibration is needed:
1. Adjust the on board reference voltage. First, adjust VR1 until the
reference voltage on TP4 has reached +5.0000 V. Next, to write
0x0080, 0x0180, 0x0280 and 0x0380 sequentially to the
Calibration Command and Data register (BASE+18) set
MIC-3716 to AI software trigger and calibration mode.
2. Adjust the PGA offset voltage. First, write any value to BASE+9
to clear FIFO. Then set A/D channel to channel 0.
3. Write the value from 0x0200 to 0x02FF sequentially to the
Calibration Command and Data register (BASE+18), and get
each bipolar range' s data by the software trigger A/D method.
Repeat this procedure 1000 times then average those data for each
value. After that, compare the average data of the range between
±5 V and ±0.625 V, to see whether the discrepancy is less then 2
LSB. If so, go to the next step. Otherwise, you must change the
value and repeat the whole procedure in this step again until the
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