Bt8370/8375/8376
Fully Integrated T1/E1 Framer and Line Interface
3.16 Data Link Registers
Abort status is reported if the receiver detects a string of 7 or more consecutive 1s during an
HDLC message. FCS error status is reported if FCS mode is enabled, and the checksum
calculated over the received HDLC message does not match the received 16-bit FCS.
Non-integer error status is reported if the receiver detects a closing FLAG character that yields
an HDLC message length that is not an integer number of 8-bit octets.
00 = Good
01 = FCS/Non-integer
10 = Abort
11 = Partial
RDL1_CNT[5:0]
Byte Count [5:0]—Indicates the number of Message Data [WORD1] bytes stored in
subsequent consecutive FIFO locations and which constitute one received message. The
reported byte count is the actual number of bytes, from 0 to 63 bytes, where 0 indicates 0 bytes
for the processor to read. The processor can either read the specified number of message data
bytes consecutively from RDL1, or poll RDL1_STAT after reading each data byte until
RDL1_STAT reports an end of message (i.e., RMPTY1=1 or RSTAT1=1).
WORD1: Message Data
7
6
5
4
3
2
1
0
RDL1[7]
RDL1[6]
RDL1[5]
RDL1[4]
RDL1[3]
RDL1[2]
RDL1[1]
RDL1[0]
RDL1[7:0]
Receive Message Data—Filled by the receiver data link, from LSB to MSB, with bits from the
selected channel. The processor reads 8-bit FIFO data during HDLC and Pack8 modes. During
Pack6 mode, only the six least significant bits RDL1[5:0] are filled.
0A9—RDL #1 Status (RDL1_STAT)
7
6
5
4
3
2
1
0
—
—
—
RMSG1
RSTAT1
RMPTY1
RNEAR1
RFULL1
RMSG1
In-Progress Receive Message—Real time status of receive message sequencer is provided
mostly for processor-polled applications. During HDLC modes, RMSG1 is high for the
interval between opening and closing FLAG characters to indicate that the receiver is filling
FIFO locations (in which case RSTAT1 is also held high). RMSG1 is low while the channel
receives FLAG or abort characters. During unformatted modes, RMSG1 is high continuously.
0 = channel idle
1 = channel actively filling FIFO
RSTAT1
Next, FIFO Read Equals Message Status—For non-empty FIFO conditions (RMPTY1=0),
RSTAT1 indicates that the next byte read from RDL1 returns WORD0 message status or
WORD1 message data. RSTAT1 equals zero if the FIFO is empty and no message is
in-progress. The processor polls RSTAT1 before reading RDL1 to determine how to interpret
RDL1 read byte value, or the processor checks RSTAT1 in response to RMSG interrupt [ISR2;
addr 009].
0 = RDL1 byte equals Message Data (or empty FIFO, if RMTPY1=1)
1 = RDL1 byte equals Message Status (if RMPTY1=0)
N8370DSE
Conexant
3-97
CONEXANT [ CONEXANT SYSTEMS, INC ]
