Intel PXA26X - Manual (Page 494)

13-32 Intel® PXA26x Processor Family Developer’s Manual
AC97 Controller Unit
13.8.3.18 Accessing 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 formulas
below 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 13-24 .
Figure 13-11. Modem Transmit and Receive Operation
TxEntry0
TxEntry1
TxEntry2
TxEntry3
TxEntry15
15 0
RxEntry0
RxEntry1
RxEntry2
RxEntry3
RxEntry15
15 0
MODR Register
31 0
Processor/DMA Processor DMA
Modem Transmit FIFO Modem Receive FIFO
15 16
0x0000
Write Read
Transmit
data Receive
Data