ds2156gn Maxim Integrated Products, Inc., ds2156gn Datasheet - Page 145

• Manufacturer Part Number: ds2156gn
• Description: Ds2156, Ds2156l, Ds2156ln T1/e1/j1 Single-chip Transceiver Tdm/utopia Ii Interface
• Manufacturer: Maxim Integrated Products, Inc.

22.3.3
The transmit FIFO buffer-available register indicates the number of bytes that can be written into the
transmit FIFO. The count form this register informs the host as to how many bytes can be written into the
transmit FIFO without overflowing the buffer.
Register Name:
Register Description:
Register Address:
Bit #
Name
Default
Bits 0 to 7/Transmit FIFO Bytes Available (TFBAO to TFBA7). TFBA0 is the LSB.
22.3.4
The lower 7 bits of the receive packet-bytes available register indicates the number of bytes (0 through
127) that can be read from the receive FIFO. The value indicated by this register (lower seven bits)
informs the host as to how many bytes can be read from the receive FIFO without going past the end of a
message. This value refers to one of four possibilities: the first part of a packet, the continuation of a
packet, the last part of a packet, or a complete packet. After reading the number of bytes indicated by this
register, the host then checks the HDLC information register for detailed message status.
If the value in the HxRPBA register refers to the beginning portion of a message or continuation of a
message, then the MSB of the HxRPBA register returns a value of 1. This indicates that the host can
safely read the number of bytes returned by the lower seven bits of the HxRPBA register, but there is no
need to check the information register since the packet has not yet terminated (successfully or otherwise).
Register Name:
Register Description:
Register Address:
Bit #
Name
Default
Bits 0 to 6/Receive FIFO Packet Bytes Available Count (RPBA0 to RPBA6). RPBA0 is the LSB.
Bit 7/Message Status (MS)
0 = bytes indicated by RPBA0 through RPBA6 are the end of a message. Host must check the INFO5 or
INFO6 register for details.
1 = bytes indicated by RPBA0 through RPBA6 are the beginning or continuation of a message. The host
does not need to check the INFO5 or INFO6 register.
FIFO Information
TFBA7
Receive Packet-Bytes Available
MS
7
7
0
0
TFBA6
RPBA6
H1TFBA, H2TFBA
HDLC # 1 Transmit FIFO Buffer Available
HDLC # 2 Transmit FIFO Buffer Available
9Fh, Afh
H1RPBA, H2RPBA
HDLC # 1 Receive Packet Bytes Available
HDLC # 2 Receive Packet Bytes Available
9Ch, ACh
6
0
6
0
TFBA5
RPBA5
5
0
5
0
RPBA4
TFBA4
4
0
4
0
145 of 265
RPBA3
TFBA3
3
0
3
0
TFBA2
RPBA2
2
0
2
0
TFBA1
RPBA1
1
0
1
0
TFBA0
RPBA0
0
0
0
0