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DS3171/DS3172/DS3173/DS3174
158
Bit 3: Transmit Bit Reordering Enable (TBRE)
– When 0, bit reordering is disabled (The first bit transmitted is the
LSB of the Transmit FIFO Data byte TFD[0]). When 1, bit reordering is enabled (The first bit transmitted is the MSB
of the Transmit FIFO Data byte TFD[7]).
Bit 2: Transmit Data Inversion Enable (TDIE)
– When 0, the outgoing data is directly output from packet
processing. When 1, the outgoing data is inverted before being output from packet processing.
Bit 1: Transmit FCS Processing Disable (TFPD)
– This bit controls whether or not an FCS is calculated and
appended to the end of each packet. When 0, the calculated FCS bytes are appended to the end of the packet.
When 1, the packet is transmitted without an FCS.
Bit 0: Transmit FIFO Reset (TFRST)
– When 0, the Transmit FIFO will resume normal operations, however, data
is discarded until a start of packet is received after RAM power-up is completed. When 1, the Transmit FIFO is
emptied, any transfer in progress is halted, the FIFO RAM is powered down, and all incoming data is discarded (all
TFDR register writes are ignored).
Register Name:
HDLC.TFDR
Register Description:
HDLC Transmit FIFO Data Register
Register Address:
(0,2,4,6)A2h
Bit
# 15 14 13 12 11 10 9 8
Name TFD7 TFD6 TFD5 TFD4 TFD3 TFD2 TFD1 TFD0
Default
0 0 0 0 0 0 0 0
Bit
# 7 6 5 4 3 2 1 0
Name
-- -- -- -- -- -- --
TDPE
Default
0 0 0 0 0 0 0 0
Note: The FIFO data and status are loaded into the Transmit FIFO when the Transmit FIFO Data (TFD[7:0]) is
written (upper byte write). When read, the value of these bits is always zero.
Bits 15 to 8: Transmit FIFO Data (TFD[7:0])
– These eight bits are the packet data to be stored in the Transmit
FIFO. TFD[7] is the MSB, and TFD[0] is the LSB. If bit reordering is disabled, TFD[0] is the first bit transmitted, and
TFD[7] is the last bit transmitted. If bit reordering is enabled, TFD[7] is the first bit transmitted, and TFD[0] is the
last bit transmitted.
Bit 0: Transmit FIFO Data Packet End (TDPE)
– When 0, the Transmit FIFO data is not a packet end. When 1,
the Transmit FIFO data is a packet end.