Bt8370/8375/8376
Fully Integrated T1/E1 Framer and Line Interface
3.16 Data Link Registers
0A7—RDL #1 FIFO Fill Control (RDL1_FFC)
7
6
5
4
3
2
1
0
MSG_FILL[1]
MSG_FILL[0]
FFC[5]
FFC[4]
FFC[3]
FFC[2]
FFC[1]
FFC[0]
MSG_FILL[1:0]
Unformatted Message Fill Limit—Applicable only for Pack8 and Pack6 modes, the message
fill limit selects how many receive FIFO locations [RDL1; addr 0A8] are filled before the
receive data link generates an RFULL interrupt [ISR2; addr 009] and generates a
corresponding RDL1 Partial message status word entry. Fill limit determines how many bytes
constitute an unformatted message, and also gives the processor an alternative to using
RNEAR interrupts to signal the end of a received unformatted message.
The number of bits per unformatted message must divide evenly by the number of bits
monitored per multiframe. For example, SLC applications monitor Fs-bits during even frames
for a total of 36 bits monitored out of 72 frames. Using Pack6 mode, that group of 36 Fs-bits
from each SLC multiframe can be chosen to constitute one unformatted message by selecting a
message fill limit which equals 6 bytes (of 6 bits/byte). In the SLC example, an RFULL
interrupt would be generated every 9 ms on each SLC multiframe boundary. Fill limits
provided for T1 cases are multiples of 6 bytes (i.e., 6, 12 or 18 FIFO locations) to hold one or
more multiframes of monitored data. In E1 mode, fill limits are specified in multiples of 8
bytes to correspond with the 16-frame multiframe lengths (i.e., monitoring CRC4 in MFAS
framing mode, or monitoring TS16 in CAS framing mode).
T1/E1N
MSG_FILL[1:0]
Message Fill Limit
Disabled
8 bytes
X
0
0
0
1
1
1
00
01
10
11
01
10
11
16 bytes
24 bytes
6 bytes
12 bytes
18 bytes
N8370DSE
Conexant
3-95
CONEXANT [ CONEXANT SYSTEMS, INC ]
