CN8478/CN8474A/CN8472A/CN8471A
5.0 Memory Organization
Multichannel Synchronous Communications Controller (MUSYCC™)
5.2 Descriptors
Tables 5-22 and 5-23 list the transmit and receive buffer descriptors and
definitions.
Table 5-22. Transmit Buffer Descriptor
Bit
Field
Name
Value
Description
31
OWNER
0
HOST Owns Buffer. HDLC channel remains in idle mode while polling this bit periodically (if
NP = 0) until host relinquishes control to MUSYCC by setting OWNER = 1. In transparent
mode the channel is deactivated.
1
0
MUSYCC Owns Buffer. Continue processing data buffer normally.
30
NP
Poll Enabled. If OWNER = 0, host-owned, MUSYCC polls the message descriptor
periodically while in idle mode until OWNER = 1.
1
Poll Disabled. If OWNER = 0, then waits for a Channel Activate or Jump Service Request
from host.
29
28
EOM
EOBI
0
1
0
Data Buffer w/o End of Message.
Data Buffer w/ End of Message.
End of Buffer Interrupt Disabled. When no more data can be taken from or put into a data
buffer, an EOB interrupt is not generated.
1
0
0
1
2
3
0
End of Buffer Interrupt Enabled.
Reserved.
27
26:25
IC[1:0]
Idle Code Select – 7Eh
Idle Code Select – FFh
Idle Code Select – 00h
Reserved.
24
PADEN
Pad Fill Disabled. One shared opening/closing flag (7Eh) is inserted before sending next
message.
1
Pad Fill Enabled. Also, see PADCNT bit field.
23:16
PADCNT[7:0]
Pad Count. When PADEN = 1, PADCNT indicates the minimum number of idle codes to be
inserted between the closing flags and the next opening flag (7Eh). If PADCNT = 2 and
IC = 1, for example, MUSYCC outputs the bit pattern 7Eh..FFh..FFh..7Eh. There is no
indication by MUSYCC if more than PADCNT number of idle codes are inserted.
15
REPEAT
0
1
0
Repeat message transmission disabled.
Repeat message transmission enabled.
Reserved.
14
RSVD
13:0
BLEN[13:0]
Buffer Length. The number of octets in data buffer to be transmitted. In general, this would
equal the allocated buffer size.
100660E
Conexant
5-33
CONEXANT [ CONEXANT SYSTEMS, INC ]
