Locking To The Aes Input Word Clock; Octal Select Register - Lexicon 960L Service Manual

3
2
1
0

Locking to the AES Input Word Clock

The procedure to derive the system word clock from an AES input stream is as follows:
1. Set bit 0 of the Lock Register low and bit 1 high to enter seek mode.
2. Program the selected Crystal AES receiver to be in master mode by setting bit 1 of the receiver's
Control Register 2 high. Bit 2 of the Interrupt Enable register of all of the Crystal receivers should also
be set high.
3. Wait at least 10 mSec.
4. Set bit 1 of the Lock Register low to exit seek mode.
5. Program the selected Crystal AES receiver to be in slave mode by setting 1 of the receiver's Control
Register 2 low.
6. Set bit 0 of the Lock Register high to drive clocks to the Crystal receivers. The system is now locked the
selected AES stream. If the cable is disconnected or the sample rate is out of range then this procedure
will need to be repeated to reestablish lock. Software should monitor the loss of lock status in the
selected AES receiver to detect loss of AES signal, and should also monitor slipped sample to detect
an input stream that is out of the accepted sample rate range.
7. Global TX Reset Chip Select
This address is decoded as a simultaneous chip select for all four Crystal AES transmitters. This location
should be used to reset all four devices within the same word clock period. This technique will ensure that
the AES transmitters' NRZI streams are aligned properly.

Octal Select Register

Register Bit
Number
7
6
5
4
3
2
1
0
Hex value
3
2
1
0
(not used)
(not used)
Enter word clock seek mode (see following
discussion)
Drive clocks to Crystal receivers (see following
discussion)
Function
Not used
Not used
Not used
Output octal group = Tmix #1 Octals 0
& 1
Output octal group = Tmix #1 Octals 10
& 11
Output octal group = Tmix #1 Octals 2
& 3
Input octal group select encoded bit 1
Input octal group select encoded bit 0
Selected Input Octal Group
(not used)
Tmix #2 Octals 8 & 9
Tmix #2 Octals 10 & 11
Tmix #2 Octals 2 & 3
Lexicon
-
-
high
high
Active State
-
-
-
High
High
High
See following table
See following table
7-31