
DS3171/DS3172/DS3173/DS3174
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Bit 3: Receive Bit Reordering Enable (RBRE)
– When 0, bit reordering is disabled (The first bit received is in the
LSB of the Receive FIFO Data byte RFD[0]). When 1, bit reordering is enabled (The first bit received is in the MSB
of the Receive FIFO Data byte RFD[7]).
Bit 2: Receive Data Inversion Enable (RDIE)
– When 0, the incoming data is directly passed on for packet
processing. When 1, the incoming data is inverted before being passed on for packet processing.
Bit 1: Receive FCS Processing Disable (RFPD)
– When 0, FCS processing is performed (the packets have an
FCS appended). When 1, FCS processing is disabled (the packets do not have an FCS appended).
Bit 0: Receive FIFO Reset (RFRST)
– When 0, the Receive 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 Receive FIFO is
emptied, any transfer in progress is halted, the FIFO RAM is powered down, the RHDA bit is forced low, and all
incoming data is discarded.
Register Name:
Register Description:
Register Address:
Bit #
Name
Bit #
Name
Bit 2: Receive FIFO Full (RFF)
– When 0, the Receive FIFO contains 255 or less bytes of data. When 1, the
Receive FIFO is full.
HDLC.RSR
HDLC Receive Status Register
(0,2,4,6)B4h
15
--
14
--
13
--
12
--
11
--
10
--
9
--
8
--
7
--
6
--
5
--
4
--
3
--
2
1
0
RFF
RFE
RHDA
Bit 1: Receive FIFO Empty (RFE)
– When 0, the Receive FIFO contains at least one byte of data. When 1, the
Receive FIFO is empty.
Bit 0: Receive HDLC Data Available (RHDA)
– When 0, the Receive FIFO contains less data than the Receive
HDLC data available level (RDAL[4:0]). When 1, the Receive FIFO contains the same or more data than the
Receive HDLC data available level.
Register Name:
Register Description:
Register Address:
Bit #
Name
Bit #
Name
Bit 7: Receive FIFO Overflow Latched (RFOL)
– This bit is set when a Receive FIFO overflow condition occurs.
An overflow condition results in a loss of data.
HDLC.RSRL
HDLC Receive Status Register Latched
(0,2,4,6)B6h
15
--
14
--
13
--
12
--
11
--
10
--
9
--
8
--
7
6
--
5
--
4
3
2
1
--
0
RFOL
RPEL
RPSL
RFFL
RHDAL
Bit 4: Receive Packet End Latched (RPEL)
– This bit is set when an end of packet is stored in the Receive FIFO.
Bit 3: Receive Packet Start Latched (RPSL)
– This bit is set when a start of packet is stored in the Receive FIFO.
Bit 2: Receive FIFO Full Latched (RFFL)
– This bit is set when the RFF bit transitions from 0 to 1.
Bit 0: Receive HDLC Data Available Latched (RHDAL)
– This bit is set when the RHDA bit transitions from 0 to
1.