CN8478 Datasheet, PDF (119/221 Pages) Conexant Systems, Inc – Multichannel Synchronous Communications Controller (MUSYCC)

CN8478/CN8474A/CN8472A/CN8471A
Multichannel Synchronous Communications Controller (MUSYCC™)
5.0 Memory Organization
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 MUSYCC Owns Buffer. Continue processing data buffer normally.
30
NP
0 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
EOM
0 Data Buffer w/o End of Message.
1 Data Buffer w/ End of Message.
28
EOBI
0 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 End of Buffer Interrupt Enabled.
27
0 Reserved.
26:25
IC[1:0]
0 Idle Code Select – 7Eh
1 Idle Code Select – FFh
2 Idle Code Select – 00h
3 Reserved.
24
PADEN
0 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 Repeat message transmission disabled.
1 Repeat message transmission enabled.
14
RSVD
0 Reserved.
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