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Intel® PXA255 Processor Developer’s Manual 13-11
AC’97 Controller Unit
SLOTREQ bits are independent of the Control Register Index bits.
Note: Slot requests for Slot 3 and Slot 4 are always set or cleared in tandem (both are set or both are
cleared).
13.4.2.3 Slot 2: Status Data Port
Slot 2 delivers 16-bit control register read data.
Note: If Slot 2 is tagged invalid, the CODEC fills the entire slot with zeroes.
13.4.2.4 Slot 3: PCM Record Left Channel
Slot 3 contains the CODEC left channel output.
The CODEC transmits its ADC output data (MSB first) and fills any trailing non-valid bit positions
with zeroes.
13.4.2.5 Slot 4: PCM Record Right Channel
Slot 4 contains the CODEC right-channel output.
The CODEC transmits its ADC output data (MSB first), and fills any trailing non-valid bit
positions with zeroes.
13.4.2.6 Slot 5: Optional Modem Line CODEC
Slot 5 contains MSB justified line modem ADC output data (if the line modem CODEC is
supported).
The ACUNIT only supports a 16-bit ADC output resolution from the optional line modem.
13.4.2.7 Slot 6: Optional Dedicated Microphone Record Data
Slot 6 contains an optional third PCM system-input channel available for dedicated use by a
microphone. This input channel supplements a true stereo output to enable a more precise echo-
cancellation algorithm for speakerphone applications.
4 Slot 10 request: NA
3 Slot 11 request: NA
2 Slot 12 request: NA
1,0 reserved (Filled with zero)
Table 13-5. Input Slot 1 Bit Definitions (Sheet 2 of 2)
Table 13-6. Input Slot 2 Bit Definitions
Bit Name Description
Bit(19:4) Control register read data Filled with data
Bit(3:0) reserved Filled with zeroes