BL4S100 User’s Manual
29
3.4.1 A/D Converter Calibration
When you start to develop your application, run
USERBLOCK_READ_WRITE.C
in the
SAMPLES\UserBlock
folder to save the factory calibration constants in case you inad-
vertently write over them while running the sample programs.
To get the best results from the A/D converter, it is necessary to calibrate each mode
(single-ended, differential, and current) for each of its gains. It is imperative that you cali-
brate each of the A/D converter inputs in the same manner as they are to be used in the
application. For example, if you will be performing floating differential measurements or
differential measurements using a common analog ground, then calibrate the A/D con-
verter in the corresponding manner. The calibration table in software only holds calibra-
tion constants based on mode, channel, and gain.
Other factors affecting the calibration must
be taken into account by calibrating using the same mode and gain setup as in the intended use.
Sample programs are provided to illustrate how to read and calibrate the various A/D
inputs for the three operating modes.
These sample programs are found in the
ADC
subdirectory in
SAMPLES\BL4S1xx
. See
Section 4.2.3 for more information on these sample programs and how to use them.
Mode
Read
Calibrate
Single-Ended, unipolar
ADC_RD_SE_UNIPOLAR.C ADC_CAL_SE_UNIPOLAR.C
Differential, bipolar
ADC_RD_DIFF.C
ADC_CAL_DIFF.C
4–20 mA
ADC_RD_MA.C
ADC_CAL_MA.C
