Bt8370/8375/8376
3.16 Data Link Registers
Fully Integrated T1/E1 Framer and Line Interface
TDL2_EN
Transmit Data Link 2 Enable—When enabled, the transmitter begins to empty and format the
contents of the transmit data link FIFO for output during the selected time slot bits, according
to the selected DL2[1:0] mode. It also enables generation of transmitter data link interrupt
events.
0 = disabled
1 = enable transmit data link
RDL2_EN
Receive Data Link 2 Enable—When enabled, the receiver begins to format data from the
selected time slot bits and fill the receive data link FIFO according to the selected DL2[1:0]
mode. It also enables generation of receiver data link interrupt events.
0 = disabled
1 = enable receive data link
0B2—RDL #2 FIFO Fill Control (RDL2_FFC)
NOTE:
Not available in Bt8376 device.
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 [RDL2; addr 0B3] are filled before the
receive data link generates an RFULL interrupt [ISR1; addr 00A] and before the data link
generates a corresponding RDL2 Partial message status word entry. Fill limits determine how
many bytes constitute an unformatted message, and give 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 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
FFC[5:0]
Near Full FIFO Threshold—Selects FIFO depth of near full interrupt [RNEAR; addr 00A] and
near full level status [RNEAR2; addr 0B4]. The RNEAR interrupt and RNEAR2 indicator are
both activated when the number of empty FIFO locations equals the selected threshold. The
threshold controls how many data and/or status bytes (64 minus threshold value) the processor
3-104
Conexant
N8370DSE
CONEXANT [ CONEXANT SYSTEMS, INC ]
