CDB5378 Datasheet, PDF (42/72 Pages) Cirrus Logic – Single-channel Seismic Evaluation System

CDB5378
3.3.5 Gain / Offset
The Gain / Offset sub-panel controls the digital filter GAIN and OFFSET registers.
The OFFSET and GAIN registers can be manually written with any 24-bit 2’s complement value from
0x800000 to 0x7FFFFF. The USEGR, USEOR, ORCAL, and EXP[4:0] values enable gain correction, off-
set correction, and offset calibration in the digital filter.
The offset calibration routine built into the digital filter is enabled by writing the ORCAL and EXP[4:0] bits.
The EXP[4:0] value can range from 0x00 to 0x18 and represents an exponential shift of the calibration
feedback, as described in the digital filter data sheet. Offset calibration results are automatically written to
the OFFSET registers and remain there, even after offset calibration is disabled.
Control
Gain
Offset
Read
Write
USEGR
USEOR
ORCAL
EXP[4:0]
Description
Displays the digital filter GAIN register.
Displays the digital filter OFFSET register.
Reads values from the GAIN and OFFSET registers.
Writes values to the GAIN and OFFSET registers.
Enables gain correction. When enabled, output samples are gained down by the
value in the GAIN register.(Output = GAIN / 0x7FFFFF).
Enables offset correction. When enabled, output samples are offset by the value in
the OFFSET register. (Output = Sample - OFFSET).
Enables offset calibration using the exponent value from the EXP[4:0] control.
Results are automatically written to the OFFSET registers as they are calculated.
Sets the exponential value used by offset calibration.
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DS639DB3