DS3181/DS3182/DS3183/DS3184
256
12.7 HDLC
12.7.1 HDLC Transmit Side Register Map
The transmit side uses five registers.
Table 12-27. Transmit Side HDLC Register Map
ADDRESS
REGISTER
REGISTER DESCRIPTION
(0,2,4,6)A0h
HDLC Transmit Control Register
(0,2,4,6)A2h
HDLC Transmit FIFO Data Register
(0,2,4,6)A4h
HDLC Transmit Status Register
(0,2,4,6)A6h
HDLC Transmit Status Register Latched
(0,2,4,6)A8h
HDLC.TSRIE HDLC Transmit Status Register Interrupt Enable
(0,2,4,6)AAh
—
Unused
(0,2,4,6)ACh
—
Unused
(0,2,4,6)AEh
—
Unused
12.7.1.1 Register Bit Descriptions
Register Name:
HDLC.TCR
Register Description:
HDLC Transmit Control Register
Register Address:
(0,2,4,6)A0h
Bit #
15
14
13
12
11
10
9
8
Name
—
TDAL4
TDAL3
TDAL2
TDAL1
TDAL0
Default
0
1
0
Bit #
7
6
5
4
3
2
1
0
Name
—
TPSD
TFEI
TIFV
TBRE
TDIE
TFPD
TFRST
Default
0
Bits 12 to 8: Transmit HDLC Data Storage Available Level (TDAL[4:0]) – These five bits indicate the minimum
number of bytes ([TDAL*8]+1) that must be available for storage (do not contain data) in the Transmit FIFO for
HDLC data storage to be available. For example, a value of 21 (15h) results in HDLC data storage being available
(THDA = 1) when the Transmit FIFO has 169 (A9h) bytes or more available for storage, and HDLC data storage
not being available (THDA = 0) when the Transmit FIFO has 168 (A8h) bytes or less available for storage. Default
value (after reset) is 128 bytes minimum available.
Bit 6: Transmit Packet Start Disable (TPSD) – When 0, the Transmit Packet Processor will continue sending
packets after the current packet end. When 1, the Transmit Packet Processor will stop sending packets after the
current packet end.
Bit 5: Transmit FCS Error Insertion (TFEI) – When 0, the calculated FCS (inverted CRC-16) is appended to the
packet. When 1, the inverse of the calculated FCS (non-inverted CRC-16) is appended to the packet causing a
FCS error. This bit is ignored if transmit FCS processing is disabled (TFPD = 1).
Bit 4: Transmit Inter-frame Fill Value (TIFV) – When 0, inter-frame fill is done with the flag sequence (7Eh).
When 1, inter-frame fill is done with all ‘1’s.
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.