BT8376EPF datasheet(227/323 Pages) CONEXANT

227 / 323 page

Bt8370/8375/8376

Fully Integrated T1/E1 Framer and Line Interface

3.16 Data Link Registers

N8370DSE

Conexant

3-109

0B8—Transmit Data Link FIFO #2 (TDL2)

NOTE:

Not available in Bt8376 device.

TDL2[7:0]

Transmit Message Data—Output by the transmitter data link from LSB to MSB sent on

selected time slot bits. The processor writes 8-bit FIFO data during HDLC and Pack8 modes.

During Pack6 mode, only the 6 least significant bits TDL2[5:0] are used.

0B9—TDL #2 Status (TDL2_STAT)

NOTE:

Not available in Bt8376 device

TMSG2

In-Progress Transmit Message—The real-time status of the transmit message sequencer is

provided mostly for diagnostic purposes. During HDLC modes, TMSG2 is high for the

interval between opening and closing FLAG characters to indicate the transmitter is actively

pulling data bytes from transmit FIFO locations. TMSG2 is low while the channel transmits

FLAG or abort characters. During Unformatted and Circular Buffer modes, TMSG2 is

continuously high.

0 = channel idle

1 = channel actively emptying FIFO

TMPTY2

Transmit FIFO Empty—Indicates that no message data is present in the transmit data link

FIFO. This is typically checked by the processor in response to a TMSG or TNEAR interrupt.

If a TMSG interrupt occurs, the processor checks TMPTY2 to verify that all queued messages

were sent (TMPTY2=1) or that more queued messages remain to be sent (TMPTY2=0). If

TNEAR interrupt occurs, the processor confirms TMPTY2=0 to verify that the partial transmit

message was not aborted by a FIFO underrun.

0 = FIFO contains data to be transmitted

1 = FIFO empty

TNEAR2

Transmit FIFO Near Empty—Indicates that the data link has emptied the transmit FIFO to

below the near empty threshold as specified in FEC[5:0]. After sending the byte that occupied

the near empty FIFO threshold level, TNEAR2 goes active-high, which generates a TNEAR

interrupt. The processor must write data to TDL2 to fill the transmit FIFO beyond the near

empty threshold to clear TNEAR2 status and enable the next TNEAR interrupt event.

0 = FIFO depth is below the near empty level

1 = FIFO has been emptied past the near empty level

TFULL2

Transmit FIFO Full—Indicates the processor has filled 64 byte locations in the transmit FIFO.

While TFULL2 remains active, subsequent processor writes to TDL2 are ignored. If the

processor inadvertently writes to TDL2 while TFULL2 is active, the processor must allow

FIFO to become completely empty without writing to TDL2_EOM, to force the transmitter to

send an Abort character.

0 = FIFO is less than full

1 = FIFO has been completely filled

TDL2[7]

TDL2[6]

TDL2[5]

TDL2[4]

TDL2[3]

TDL2[2]

TDL2[1]

TDL2[0]

————

TMSG2

TMPTY2

TNEAR2

TFULL2

BT8376EPF Datasheet(PDF) 227 Page - Synaptics Incorporated.

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