3.0 Registers
CX28394/28395/28398
3.15 Data Link Registers
Quad/x16/Octal—T1/E1/J1 Framers
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
then 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 1 or more multiframes
worth 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 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 009] and
near full level status [RNEAR1; addr 0A9]. The RNEAR interrupt and RNEAR1 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) that the
processor must read from RDL1 after RNEAR interrupt. This is done to clear the RNEAR1
indicator as well as to determine how much time remains (in bytes) for the processor to read
RDL1 before the receive FIFO is full. If a receive message is in progress when the near full
threshold is reached, the receiver issues a message interrupt [RMSG; addr 009] and places a
Partial message in the receive FIFO.
FFC[5:0]
00 0000
00 0001
00 0010
|
Empty @ RNEAR
Filled @ RNEAR
64 = RFULL
none
1 empty FIFO location
2 empty FIFO locations
|
63 filled
62 filled
|
11 1110
11 1111
62 empty FIFO locations
63 empty FIFO locations
1 filled
0 filled = empty
3-78
Conexant
100054E
CONEXANT [ CONEXANT SYSTEMS, INC ]
