Bt8370/8375/8376
Fully Integrated T1/E1 Framer and Line Interface
3.16 Data Link Registers
0B8—Transmit Data Link FIFO #2 (TDL2)
NOTE:
Not available in Bt8376 device.
7
6
5
4
3
2
1
0
TDL2[7]
TDL2[6]
TDL2[5]
TDL2[4]
TDL2[3]
TDL2[2]
TDL2[1]
TDL2[0]
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
7
6
5
4
3
2
1
0
—
—
—
—
TMSG2
TMPTY2
TNEAR2
TFULL2
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
TFULL2
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
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
N8370DSE
Conexant
3-109
CONEXANT [ CONEXANT SYSTEMS, INC ]
