BT8376EPF datasheet(224/323 Pages) CONEXANT

224 / 323 page

Bt8370/8375/8376

3.16 Data Link Registers

Fully Integrated T1/E1 Framer and Line Interface

3-106

Conexant

N8370DSE

0B3—Receive Data Link FIFO #2 (RDL2)

NOTE:

Not available in Bt8376 device.

Two different read byte values are supplied: WORD0 equals message status, and WORD1

equals message data. The processor determines which byte value is located in the FIFO by first

reading the receiver data link status [RDL2_STAT; addr 0B4]. In some cases, multiple

consecutive status bytes can be placed in the FIFO, so the processor must always read

RDL2_STAT before reading RDL2 to distinguish between WORD0 and WORD1 byte values.

However, each time a non-0 byte count [RDL2_CNT] status is read, the processor is

guaranteed that the next byte read from RDL2 is message data [WORD1], not message status.

Status byte and a message data byte each occupies 1 byte of FIFO space.

WORD0: Message Status

EOM[1, 0]

End of Message—The receive data link reports an End of Message status for each occurrence

of a complete (Good), a continued (Partial), an errored (FCS/Non-integer), or an aborted

(Abort) message. Properly received unformatted messages are reported with a Partial end of

message status. The processor responds to Good or Partial status by reading the indicated

number of data bytes [RDL2_CNT] from RDL2. For abort or error cases, RDL2_CNT equals

0 to indicate all received data from that message was discarded.

Note that A Good status with RDL2_CNT=0 is reported if the processor reads RDL2 while

the receiver is in progress of filling the FIFO (in which case RDL2_STAT contains RSTAT2=1

and RMSG2=1). If an abort or error status with 0 byte count is reported after the processor has

buffered a prior HDLC Partial message, that partial buffered processor data must be discarded.

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 which is not an integer number of 8-bit octets.

00 = Good

01 = FCS/Non-integer

10 = Abort

11 = Partial

RDL2_CNT[5:0]

Byte Count [5:0]—Indicates the number of Message Data [WORD1] bytes stored in

subsequent consecutive FIFO locations, constituting one received message. The reported byte

count is the actual number of bytes from 0 to 63, where 0 indicates 0 bytes for the processor to

read. The processor can read either the specified number of message data bytes consecutively

from RDL2, or poll RDL2_STAT after reading each data byte until RDL2_STAT reports an

end of message (i.e., RMPTY2=1 or RSTAT2=1).

WORD1: Message Data

RDL2[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 6 least significant bits RDL2[5:0] are filled.

EOM[1]

EOM[0]

RDL2_CNT[5]

RDL2_CNT[4]

RDL2_CNT[3]

RDL2_CNT[2]

RDL2_CNT[1]

RDL2_CNT[0]

RDL2[7]

RDL2[6]

RDL2[5]

RDL2[4]

RDL2[3]

RDL2[2]

RDL2[1]

RDL2[0]

BT8376EPF Datasheet(PDF) 224 Page - Synaptics Incorporated.

BT8376EPF Datasheet(HTML) 224 Page - Synaptics Incorporated.

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