
DS3171/DS3172/DS3173/DS3174
159
Register Name:
HDLC.TSR
Register Description:
HDLC Transmit Status Register
Register Address:
(0,2,4,6)A4h
Bit
# 15 14 13 12 11 10 9 8
Name -- -- TFFL5 TFFL4 TFFL3 TFFL2 TFFL1 TFFL0
Bit
# 7 6 5 4 3 2 1 0
Name
-- -- -- -- --
TFF TFE THDA
Bits 13 to 8: Transmit FIFO Fill Level (TFFL[5:0])
– These six bits indicate the number of eight byte groups
available for storage (do not contain data) in the Transmit FIFO. E.g., a value of 21 (15h) indicates the FIFO has
168 (A8h) to 175 (AFh) bytes are available for storage.
Bit 2: Transmit FIFO Full (TFF)
– When 0, the Transmit FIFO contains 255 or less bytes of data. When 1, the
Transmit FIFO is full.
Bit 1: Transmit FIFO Empty (TFE)
– When 0, the Transmit FIFO contains at least one byte of data. When 1, the
Transmit FIFO is empty.
Bit 0: Transmit HDLC Data Storage Available (THDA)
– When 0, the Transmit FIFO has less storage space
available in the Transmit FIFO than the Transmit HDLC data storage available level (TDAL[4:0]). When 1, the
Transmit FIFO has the same or more storage space available than the Transmit FIFO HDLC data storage available
level.
Register Name:
HDLC.TSRL
Register Description:
HDLC Transmit Status Register Latched
Register Address:
(0,2,4,6)A6h
Bit
# 15 14 13 12 11 10 9 8
Name
-- -- -- -- -- -- -- --
Bit
# 7 6 5 4 3 2 1 0
Name -- -- TFOL TFUL TPEL -- TFEL THDAL
Bit 5: Transmit FIFO Overflow Latched (TFOL)
– This bit is set when a Transmit FIFO overflow condition occurs.
Bit 4: Transmit FIFO Underflow Latched (TFUL)
– This bit is set when a Transmit FIFO underflow condition
occurs. An underflow condition results in a loss of data.
Bit 3: Transmit Packet End Latched (TPEL)
– This bit is set when an end of packet is read from the Transmit
FIFO.
Bit 1: Transmit FIFO Empty Latched (TFEL)
– This bit is set when the TFE bit transitions from 0 to 1.
Note: This bit is also set when HDLC.TCR.TFRST is deasserted.
Bit 0: Transmit HDLC Data Available Latched (THDAL)
– This bit is set when the THDA bit transitions from 0 to
1.
Note: This bit is also set when HDLC.TCR.TFRST is deasserted.