Cirrus Logic EP93xx User Manual

Page 699

DS785UM1

22-11

AC’97 Controller

EP93xx User’s Guide

CM:

Compact mode enable. If the RSIZE value is either “00” or
“11” (setting the data word size to 12- or 16-bits) then the
CM bit determines whether the two data words are
compacted into one 32-bit word, or each is sent in a
separate word. If the RSIZE value is either “01” or “10”
(setting the data word size to 18- or 20-bits) then the CM
bit has no effect. See

Table 22-4

0 - The data is justified into one 32 bit word
1 - The two data words are compacted into one 32-bit
word for reading by the CPU.

RSIZE:

Determines how many bits to a data word. See

Table 22-4

for details of the interaction between RSIZE and CM.
00 data is 16 bits
01 data is 18 bits
10 data is 20 bits
11 data is 12 bits

TX12:

FIFO stores SLOT12 data (takes precedence over
AC97S12Data)

TX11:

FIFO stores SLOT11 data

TX10:

FIFO stores SLOT10 data

TX9:

FIFO stores SLOT9 data

TX8:

FIFO stores SLOT8 data

TX7:

FIFO stores SLOT7 data

TX6:

FIFO stores SLOT6 data

TX5:

FIFO stores SLOT5 data

TX4:

FIFO stores SLOT4 data

TX3:

FIFO stores SLOT3 data

TX2:

FIFO contains SLOT2 data (only use if sampling rate is
48 kHz). Takes precedence over AC97S2Data.

Table 22-4. Interaction Between RSIZE and CM Bits

RSIZE

Data to CPU

Justified, one 16 bits

Justified, one 12 bits

Compacted, two 16 bits

Compacted, two 12 bits

Justified, 20 bit

Justified, 18 bit