
XRT84L38
406
OCTAL T1/E1/J1 FRAMER
REV. 1.0.1
When SLC96 mode is enabled, the Fs bit is replaced by the data link message read from memory at the
beginning of each D4 super-frame. The XRT84L38 allocates two 6-byte buffers to provide the SLC96 Data
Link Controller an alternating access mechanism for information transmission. The bit ordering and usage is
shown in the following table; and the LSB is sent first. Note that these registers are memory-based storage and
they need to be initialized.
Each register is read out of memory once every six SF super-frames. The memory holding these registers
owns a shared memory structure that is used by multiple devices. These include DS1 transmit module, DS1
receive module, Transmit LAPD Controller, Transmit SLCa96 Data Link controller, Bit-Oriented Signaling
Processor, Receive LAPD Controller, Receive SLCa96 Data Link Controller, Receive Bit-Oriented Signaling
Processor and microprocessor interface module.
13.1.5.1
How to configure the SLC96 Data Link Controller to transmit SLC96 Data Link
Messages
This section describes how to configure the SLC96 Data Link Controller to transmit SLC96 Data Link
message in a step-by-step basis.
13.1.5.1.1
Step 1: Find out the next available transmit data link buffer
To transmit SLC96 Data Link message, the user is recommended to read Transmit Data Link Byte Count
Register for next available transmit buffer number.
The table below shows how contents of the Buffer Enable bit of the Transmit Data Link Byte Count Register
(TDLBCR) determines what the next available transmit buffer number is.
TRANSMIT DATA LINK BYTE COUNT REGISTER (TDLBCR) (INDIRECT ADDRESS = 0XN0H, 0X14H)
13.1.5.1.2
Step 2: Write SLC96 Data Link Message into transmit data link buffer
After finding out the next available transmit buffer, the user should write the entire message data to the
available transmit data link buffer via PIO or DMA access. The writing of these buffers is through the LAPD
Buffer 0 indirect data registers and the LAPD Buffer1 indirect data registers. LAPD Buffer 0 and 1 indirect data
registers have addresses 0xn6H and 0xn7H respectively. There is no indirect address register for transmit data
link buffer 0 and 1.
A microcontroller WRITE access to the LAPD Buffer indirect data registers will access the transmit data link
buffer and a microcontroller READ will access the receive data link buffers. The very first WRITE access to the
LAPD Buffer indirect data register will always be direct to location 0 within the transmit data link buffer. The
TRANSMIT SLC
96 MESSAGE REGISTERS
B
IT
B
YTE
5
4
3
2
1
0
1
0
1
1
1
0
0
2
C1
1
1
1
0
0
3
C7
C6
C5
C4
C3
C2
4
1
0
C11
C10
C9
C8
5
A2
A1
M3
M2
M1
0
6
0
1
S4
S3
S2
S1
B
IT
N
UMBER
B
IT
N
AME
B
IT
T
YPE
B
IT
D
ESCRIPTION
7
Buffer Select
R
0 - The next available transmit buffer for sending out BOS or MOS mes-
sage is Buffer 0.
1 - The next available transmit buffer for sending out BOS or MOS mes-
sage is Buffer 1.