Intel PXA255 manual Accessing Codec Registers, Modem Transmit and Receive Operation

Models: PXA255

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AC’97 Controller Unit

Figure 13-11. Modem Transmit and Receive Operation

Transmit data

TxEntry15

Modem Transmit FIFO

TxEntry3

TxEntry2

TxEntry1

TxEntry0

15

Processor/DMA

Processor DMA

 

Receive

 

Data

 

Write

 

 

Read

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RxEntry15

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0x0000

 

MODR Register

 

Modem Receive FIFO

 

 

 

 

 

 

 

 

 

 

31

 

1615

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RxEntry3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RxEntry2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RxEntry1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RxEntry0

 

 

 

 

 

 

 

 

 

 

 

0

0

 

 

 

 

 

 

15

 

 

13.8.3.17Accessing CODEC Registers

Each CODEC has up to sixty-four 16-bit registers that are addressable internal to the CODEC at half-word boundaries (16-bit boundaries). Because the processor only supports internal register accesses at word boundaries (32-bit boundaries), software must select the one of the following formulas to translate a 7-bit CODEC address into a 32-bit processor address:

Processor physical address for a Primary Audio CODEC

=0x4050-0200 + Shift_Left_Once(Internal 7-bit CODEC Register Address)

Processor physical address for a Secondary Audio CODEC

=0x4050-0300 + Shift_Left_Once(Internal 7-bit CODEC Register Address)

Processor physical address for a Primary Modem CODEC

=0x4050-0400 + Shift_Left_Once(Internal 7-bit CODEC Register Address)

Processor physical address for a Secondary Modem CODEC

=0x4050-0500 + Shift_Left_Once(Internal 7-bit CODEC Register Address)

In the equations, Shift_Left_Once() shifts the 7-bit CODEC address left by one bit and shifts a 0 to the LSB. The address translations are shown in Table 13-23.

13-32

Intel® PXA255 Processor Developer’s Manual

Page 484
Image 484
Intel PXA255 manual Accessing Codec Registers, Modem Transmit and Receive Operation