CS4231A Datasheet, PDF (20/76 Pages) List of Unclassifed Manufacturers – PARALLEL INTERFACE MULTIMEDIA AUDIO CODEC

CS4231A
rising edge starts the initialization process in
which a full calibration occurs. While the
CS4231A is initializing, 80 hex is returned from
all reads by the host computer. All writes during
initialization of the CS4231A will be ignored.
At the end of the initialization, all registers are
set to known reset values as documented in the
register definition section.
Calibration Modes
The CS4231A has four different calibration
modes. The selected calibration occurs whenever
the Mode Change Enable (MCE, R0) bit goes
from 1 to 0.
The completion of calibration can be determined
by polling the Auto-Calibrate In-Progress bit in
the Error Status and Initialization register (ACI,
I11). This bit will be high while the calibration is
in progress and low once completed. The cali-
bration time varies with calibration mode.
The Calibration procedure is as follows:
1) Place the CS4231A in Mode Change En-
able using the MCE bit of the Index
Address register (R0).
2) Set the CAL1,0 bits in the Interface Con-
figuration register (I9).
3) Return from Mode Change Enable by reset-
ting the MCE bit of the Index Address
register (R0).
4) Wait until ACI (I11) cleared to proceed
No Calibration (CAL1,0 = 00)
This is the fastest mode since no calibration is
performed. This mode is useful for games which
need to change the sample frequency quickly.
This mode is also useful when the codec is oper-
ating in full-duplex and an ADC data format
change is desired. This is the only calibration
mode that does not affect the DACs (i.e. mute
20
the DACs at some point). Changing from any
other calibration mode to No Calibration mode
will take 40 sample periods to complete; how-
ever, subsequent MCE cycles will take 0 sample
periods.
Converter Calibration (CAL1,0 = 01)
This calibration mode calibrates the ADCs and
DACs but does not calibrate any of the analog
mixing channels. This is the second longest cali-
bration mode, taking 136 sample periods, and is
software and hardware similar to the CS4231 or
CS4248. Since the mixer is not calibrated, any
analog signals mixing into the output will be un-
affected. The calibration sequence done by the
CS4231A is as follows:
The DACs are muted
The ADCs are calibrated
The DACs are calibrated
The DACs are unmuted
DAC Calibration (CAL1,0 = 10)
This calibration mode only calibrates the DACs’
(playback) interpolation filters leaving the ADCs
unaffected. This is the second fastest calibration
mode (no cal. is the fastest) taking 40 sample pe-
riods to complete. The calibration sequence done
by the CS4231A is as follows:
The DACs are muted
The DAC filters are calibrated
The DACs are unmuted
Full Calibration (CAL1,0 = 11)
This calibration mode calibrates all offsets,
ADCs, DACs, and analog mixers. Full calibra-
tion is automatically initiated on power up or
anytime the CS4231A exits from a power down
state. This is the longest calibration mode and
takes 168 sample periods to complete. The cali-
bration sequence done by the CS4231A is as
follows:
DS139PP2