CX28394/28395/28398
3.0 Registers
Quad/x16/Octal—T1/E1/J1 Framers
3.15 Data Link Registers
0B8—Transmit Data Link FIFO #2 (TDL2)
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 and sent on
the selected time slot bits. Processor writes 8-bit FIFO data during HDLC and Pack8 modes.
During Pack6 mode, only the six least significant bits, TDL2[5:0], are used.
0B9—TDL #2 Status (TDL2_STAT)
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 the 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 processor in response to a TMSG or TNEAR interrupt. If
this is a TMSG interrupt, the processor checks TMPTY2 to determine that all queued
messages were sent (TMPTY2=1) or more queued messages remain to be sent (TMPTY2=0).
If this is a TNEAR interrupt, the processor confirms TMPTY2=0 to verify 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 data link has emptied transmit FIFO to below the near
empty threshold 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.
This is done in order 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 processor has completely filled 64 byte locations in transmit
FIFO. While TFULL2 remains active, any subsequent processor writes to TDL2 are ignored. If
the processor should inadvertantly write to TDL2 while TFULL2 is active, the processor must
allow FIFO to become completely empty without writing to TDL2_EOM, in order to force the
transmitter to send an Abort character.
0 = FIFO is less than full
1 = FIFO has been completely filled
100054E
Conexant
3-91
CONEXANT [ CONEXANT SYSTEMS, INC ]
