![](http://datasheet.mmic.net.cn/Exar-Corporation/XRT79L71IB-F_datasheet_100145/XRT79L71IB-F_493.png)
PRELIMINARY
XRT79L71
478
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
This step will cause the value "0x03" to be written into the location that is being identified by the LAPD
Message Buffer pointer.
In this case (per Sub-STEP 6d.1, above) this will be the fourth byte of Indirect
Address 0x03 within the Transmit LAPD Message Buffer.
STEP 6e - Write in a specific value, which the remote terminal equipment can use to identify the PMDL
Message type.
Therefore, the exact value that the user must write in depends upon the type of LAPD Message being
transmitted to the Remote Terminal Equipment. Table 63 presents a mapping of the value to be written into
this byte, with the corresponding PMDL Message type, to be transmitted.
The user can accomplish all of this by executing the following two sub-steps.
Sub-STEP 6e.1 - At Address Location 0x11C0 (The LAPD Message Buffer - Indirect Address Register)
write the value "0x04".
This step will cause the internal LAPD Message Buffer pointer to point to the fifth byte of Indirect Address 0x04
within the Transmit LAPD Message Buffer.
Sub-STEP 6e.2 - At Address Location 0x11C1 (The LAPD Message Buffer - Indirect Data Register) write
the appropriate value (per Table 63) into the location that is being identified by the LAPD Message Buffer pointer.
In this case (per Sub-STEP 6e.1, above) this will be the fifth byte of Indirect Address 0x04 within the Transmit
LAPD Message Buffer.
STEP 6f - Write in the remaining 75 or 81 byte of the Information Payload within the PMDL Message into
the Transmit LAPD Message Buffer.
This is accomplished by executing the procedure that is defined and presented in the following flow-chart.
TABLE 63: A MAPPING OF THE VALUE TO BE WRITTEN INTO INDIRECT ADDRESS LOCATION 0X11B0 AND THE
CORRESPONDING
PMDL MESSAGE
PMDL MESSAGE TYPE
VALUE TO BE WRITTEN INTO ADDRESS LOCATION
0X11B0 DURING STEP 5E
Test Signal
0x32
Idle Signal
0x34
CL Path Identification
0x38
ITU Path Identification
0x3F