CS4231A Datasheet, PDF (55/76 Pages) List of Unclassifed Manufacturers – PARALLEL INTERFACE MULTIMEDIA AUDIO CODEC

CS4231A
APPENDIX A
This data sheet describes the CS4231A which is backwards compatible with the CS4231 - both hard-
ware and software. The CS4231A uses four pins that were "No Connects", on the CS4231 (for the
audio serial port). Since the CS4231 defines these pins as "No Connects", the CS4231A will drop into
a CS4231 socket and function properly, although the serial port will not be connected.
There are also software additions to the CS4231A. New bits have been defined to enhance the opera-
tion of the CS4231A. These added bits were reserved in the CS4231. The data sheet states that
reserved bits should be written as 0 and may read back as 0 or 1; therefore, properly written software
is forwards compatible with the CS4231A. The version bits V2-V0 (upper three bits of I25) distinguish
between the CS4231 and the CS4231A. The additions to the CS4231A are as follows:
1. Interface Configuration register (I9): The CAL1 bit does not exist in the CS4231. The CAL0 bit
was labeled ACAL in the CS4231 but the function was the same. The extra calibration modes in the
CS4231A better support full duplex and games software.
2. Alternate Feature Enable I register (I16): The PMCE and CMCE bits do not exist in the CS4231.
These bits were added to enhance full-duplex operation.
The serial audio data port and associated bits - SF1, SF0, SPE - do not exist on the CS4231. The
serial audio data port was added to the CS4231A to allow DSP’s and ASIC’s to act as an audio
coprocessor to the CS4231A.
3. Alternate Feature Enable II register (I17): The APAR and XTALE bits do not exist in the
CS4231. The APAR bit was added better support the ADPCM playback mechanism.
The XTALE bit was added to better support software that switches sample frequencies often, e.g.
games.
4. Alternate Feature Enable III register (I23): The ACF bit does not exist on the CS4231. This bit
better supports the ADPCM capture mechanism.
5. Version / ID register (I25): The Version number bits - V2, V1, V0 - were modified (changed to
101) to allow software to uniquely identify the CS4231A.
6. Mono Input & Output Control register (I26): The MBY bit does not exist in the CS4231. The
power up default value of this register was also changed. The extra bit and the changes will approxi-
mate the CS4231 at power-up. The difference is that the MIN pin (normally the PC beeper) is
directed to the MOUT pin - but not to the L/ROUT pins.
DS139PP2
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