cs5535 National Semiconductor Corporation, cs5535 Datasheet - Page 87

• Manufacturer Part Number: cs5535
• Description: Geode Cs5535 Companion Multi-function South Bridge
• Manufacturer: National Semiconductor Corporation

www.national.com
ACC Functional Description
transferred for a given PRD is 65534 bytes for mono
streams and 65532 bytes for stereo streams.
For stereo streams (bus masters 0, 1, and 6):
For mono streams (bus masters 2, 3, 4, 5, and 7):
Descriptions of the control flags are:
• End of Transfer (EOT) - If set in a PRD, this bit indi-
• End of Page (EOP) - If set in a PRD and the bus master
DWORD
Sample
cates the last entry in the PRD table. The last entry in a
PRD table must have either the EOT bit or the JMP bit
set. A PRD can not have both the JMP and EOT bits set.
When the bus master reaches an EOT, it stops and
clears its Bus Master Enable bit. If software desires an
IRQ to be generated with the EOT, it must set the EOP
bit and the EOT bit on the last PRD entry.
has completed the PRD’s transfer, the End of Page bit is
set (in the IRQ status register) and an IRQ is generated.
If a second EOP is reached due to the completion of
another PRD before the End of Page bit is cleared, the
Bus Master Error bit is set (in the IRQ status register)
and the bus master pauses. In this paused condition,
reading the IRQ status register clears both the Bus
Memory Region Base Address and Size should be a
multiple of four (DWORD aligned). This ensures an
equal number of left and right samples.
Memory Region Base Address and Size should be a
multiple of two (WORD aligned).
0
1
0
0
0
0
1
1
1
1
Little Endian
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
O
E
T
2 Channel,
Channel
O
E
P
Right
Right
Right
Right
Left
Left
Left
Left
M
P
J
Byte 3
Table 4-7. PCM Data format (Byte and Channel Ordering)
Byte
High
High
High
High
Low
Low
Low
Low
Table 4-6. Physical Region Descriptor (PRD) Format
Memory Region Base Address [31:0] (Address of Audio Data Buffer)
Sample
Reserved
(Continued)
Little Endian
0
0
1
1
2
2
3
3
1 Channel,
Byte 2
Byte
High
High
High
High
Low
Low
Low
Low
87
Sample
• Jump (JMP) - This PRD is special. If set, the Memory
4.3.7.3
Table 4-7 shows an example of the how PCM audio data is
stored in memory (byte order and channel order). Each row
represents a byte in memory, with increasing addresses as
you go down. The byte order can be configured via the Bus
Master Command Register for Intel (little endian) or Motor-
ola (big endian) byte ordering. Changing the byte order
ONLY affects how PCM data is interpreted. PRD entries
and register contents are always little endian. The two
channel format applies to the 32-bit bus masters handling
left and right input and output. The single channel format
applies to the 16-bit bus masters. The 32-bit bus masters
always operate on stereo data, and the 16-bit bus masters
always operate on mono data. Since there is no special
mode for playing monaural sound through the main chan-
nels (left and right), it is the responsibility of the software to
create stereo PCM data with identical samples for the left
and right channels to effectively output monaural sound.
Master Error and the End of Page bits, and the bus
master continues.
Region Base Address is now the target address of the
JMP. The target address of the JMP must point to
another PRD. There is no audio data transfer with this
PRD. This PRD allows the creation of a looping mecha-
nism. If a PRD table is created with the JMP bit set in the
last PRD, the PRD table does not need a PRD with the
EOT bit set. A PRD can not have both the JMP and EOT
bits set.
0
0
0
0
1
1
1
1
PCM Data Format and Byte Order
Big Endian
2 Channel,
Channel
Right
Right
Right
Right
Byte 1
Left
Left
Left
Left
Size [15:0]
Byte
High
High
High
High
Low
Low
Low
Low
8
7
6
Sample
5
0
0
1
1
2
2
3
3
Big Endian
1 Channel,
Byte 0
4
3
2
Revision 0.8
Byte
High
High
High
High
Low
Low
Low
Low
1
0