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13-26 Intel® PXA255 Processor Developer’s Manual
AC’97 Controller Unit
13.8.3.7 CODEC Access Register (CAR)
This is a read/write register. Ignore reads from reserved bits. Write zeros to reserved bits.
13.8.3.8 PCM Data Register (PCDR)
This is a read/write register. Ignore reads from reserved bits. Write zeros to reserved bits.
Writing a 32-bit sample to this register updates the data into the PCM Transmit FIFO. Reading this
register gets a 32-bit sample from the PCM Receive FIFO.
Table 13-13. CAR Bit Definitions
Physical Address
4050_0020
CAR Register AC’97 Controller Unit
Bit
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
reserved
CAIP
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Bits Name Description
31:1 — reserved
0CAIP
CODEC Access In Progress (CAIP)
This bit is read by software to check whether a CODEC IO cycle is currently in progress.
0 = No cycle is in progress and the act of reading the register sets this bit to ‘1’. This
reserves the right for the software driver to perform the IO cycle. Once the cycle is
complete, this bit is automatically cleared. Software can clear this bit by writing a ‘0’ to
this bit location if it decides not to perform a CODEC IO cycle after having read this bit.
1 = Indicates that another driver is performing a CODEC IO cycle across the AC-link and
the currently accessing driver must try again later. (This bit applies to all CODEC IO
cycles - GPIO or otherwise).
Table 13-14. PCDR Bit Definitions
Physical Address
4050_0040
PCDR Register AC’97 Controller Unit
Bit
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
PCM_RDATA PCM_LDATA
Reset
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Bits Name Description
31:16 PCM_RDATA PCM right-channel data
15:0 PCM_LDATA PCM left-channel data