cx28394 Conexant Systems, Inc., cx28394 Datasheet - Page 200

• Manufacturer Part Number: cx28394
• Description: Quad/x16/octal-t1/e1/j1 Framers
• Manufacturer: Conexant Systems, Inc.

3.0 Registers
3.15 Data Link Registers
FFC[5:0]
3-78
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).
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.
For example, SLC applications monitor Fs bits during even frames for a total of 36 bits
T1/E1N
FFC[5:0]
00 0000
00 0001
00 0010
11 1110
11 1111
X
0
0
0
1
1
1
|
MSG_FILL[1:0]
none
1 empty FIFO location
2 empty FIFO locations
|
62 empty FIFO locations
63 empty FIFO locations
00
01
10
11
01
10
11
Empty @ RNEAR
Conexant
Message Fill Limit
Disabled
16 bytes
24 bytes
12 bytes
18 bytes
6 bytes
8 bytes
64 = RFULL
63 filled
62 filled
|
1 filled
0 filled = empty
Quad/x16/Octal—T1/E1/J1 Framers
Filled @ RNEAR
CX28394/28395/28398
100054E