Cirrus Logic EP93xx - Manual (Page 699)

DS785UM1 22-11
Copyright 2007 Cirrus Logic
AC’97 Controller
EP93xx User’s Guide
2
2
2
2
22
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
CM RSIZE Data to CPU
0 0 0 Justified, one 16 bits
0 1 1 Justified, one 12 bits
1 0 0 Compacted, two 16 bits
1 1 1 Compacted, two 12 bits
X 1 0 Justified, 20 bit
X 0 1 Justified, 18 bit