
Preliminary Information
MT9071
147
7
6
5
4
3
2
1
0
RXF7
RXF6
RXF5
RXF4
RXF3
RXF2
RXF1
RXF0
HDLC Receive FIFO Data.
This is the received data byte read from the Receive FIFO. The
FIFO status is not changed immediately when a receiver write or processor read occurs. It is
updated after the data has settled and the transfer to the last available position has finished.
Bit
Name
Functional Description
15-9
8
(0000 000)
GAL
(0)
Not Used
Go Ahead Latch.
When the HDLC receiver detects a go-ahead pattern (01111111), this
status bit is latched to one. This bit is cleared when either this register, or the T1 & E1 HDLC
Interrupt Status - R Address Y33 is read.
End of Packet Detect Latch.
When the HDLC receiver writes an end of packet (EOP) byte
into the Receive FIFO, this status bit is latched to one. This can be in the form of a flag
(01111110), an abort sequence (x1111111x) or as an invalid packet. This bit is cleared when
either this register, or the T1 & E1 HDLC Interrupt Status - R Address Y33 is read.
Transmit End of Packet Latch.
When the HDLC transmitter has finished sending the
closing flag of a packet or after a packet has been aborted, this status bit is latched to one.
This bit is cleared when either this register, or the T1 & E1 HDLC Interrupt Status - R Address
Y33 is read.
End of Packet Read Latch.
When there is only one byte of data left in the Receive FIFO,
and this data is the last byte of the packet, this status bit is latched to one. It is also set if the
Receive FIFO is read and there is no data in it. This bit is cleared when either this register, or
the T1 & E1 HDLC Interrupt Status - R Address Y33 is read.
Transmit FIFO Low Latch.
When the HDLC transmitter empties the Transmit FIFO below
16 bytes, this status bit is latched to one. This bit is cleared when either this register, or the
T1 & E1 HDLC Interrupt Status - R Address Y33 is read.
Frame Abort Latch.
When the HDLC receiver detects an abort sequence (x1111111x), this
status bit is latched to one. Note that it must be received after a minimum number of bits have
been received (26), otherwise it is ignored. This bit is cleared when either this register, or the
T1 & E1 HDLC Interrupt Status - R Address Y33 is read.
Transmit FIFO Empty Latch.
When the HDLC transmitter reads an empty Transmit FIFO,
this status bit is latched to one. This bit is cleared when either this register, or the T1 & E1
HDLC Interrupt Status - R Address Y33 is read.
Receive FIFO High Latch.
When the Receive FIFO is filled above 16 bytes, this status bit is
latched to one. This bit is cleared when either this register, or the T1 & E1 HDLC Interrupt
Status - R Address Y33 is read.
Receive FIFO Overflow Latch.
When the HDLC receiver writes to an already full Receive
FIFO, this status bit is latched to one. This bit is cleared when either this register, or the T1 &
E1 HDLC Interrupt Status - R Address Y33 is read. The HDLC will disable the receiver once
the receive overflow has been detected. The receiver will be re-enabled upon detection of the
next flag, but will overflow again unless the Receive FIFO is read.
Table 131 - T1 & E1 HDLC Latched Status - R Address Y23
7
EOPDL
(0)
6
TEOPL
(0)
5
EOPRL
(0)
4
TXFLL
(0)
3
FAL
(0)
2
TXFEL
(0)
1
RXFHL
(0)
0
RXFOL
(0)
Bit
Name
Functional Description
Table 130 - T1 & E1 HDLC Receive FIFO Data - R/W Address Y1F