6.0 Basic Operation
CN8478/CN8474A/CN8472A/CN8471A
6.4 Protocol Support
Multichannel Synchronous Communications Controller (MUSYCC™)
Setting MCENBL to 0 prevents MUSYCC from copying the Message
Configuration Bits from the Transmit Buffer Descriptor and has the following
effect on transmit channel operations throughout the channel group:
•
•
PADEN and PADCNT are set to 0, thereby facilitating back-to-back
message transmission.
REPEAT is set to 0, thereby disabling automatic message retransmission.
Any of the Message Configuration Bits can be changed by writing new values
for these bit fields directly into a channel group’s Transmit Configuration Table.
However, the exact time the new bit field values are applied by the transmitter is
unrelated to the message being serviced. If the channel is idle, any change to the
message configuration bits in the Configuration Table will apply to subsequent
messages.
To write new configuration bits into the Transmit Message Configuration
Table, a PCI dword operation is required. Tables 6-12 and 6-13 list the address
map and the Message Configuration Descriptor layouts.
Table 6-12. Memory Map for Message Configuration Descriptor Table
Location of Message Configuration Descriptor
in Specific Group (0–3) (Byte offset from Base Address Register)
Channel
Number
(0–31)
0
1
2
3
4
5
6
7
06180h
06980h
07180h
07980h
16180h
16980h
17180h
17980h
0
1
06184h
06984h
07184h
07984h
16184h
16984h
17184h
17984h
Address of Message Configuration Descriptor for a
channel in a group
Address of Message Configuration Descriptor for a
channel in a group
x
06180h + (Group_Number[0:3]•00800h) +
16180h + (Group_Number[4:7]•00800h) +
(Channel_Number[31:0]•00008h)
(Channel_Number[31:0]•00008h)
061FCh
069FCh
071FCh
079FCh
161FCh
169FCh
171FCh
179FCh
31
Table 6-13. Message Configuration Descriptor (1 of 2)
Bit
Field
Name
Value
Description
31:27
26:25
RSVD
IC
0
0
1
2
3
Reserved.
Idle Code Select –7Eh (0111 1110b)
Idle Code Select –FFh (1111 1111b)
Idle Code Select –00h (0000 0000b)
Idle Code Select –Reserved.
6-30
Conexant
100660E
CONEXANT [ CONEXANT SYSTEMS, INC ]
