User Manual

TSI/PCM interface
99-137719-D Confidential - For internal use 7-43
7777
Data interfaces
7.9.2 Data formats
The data format for ISDN data sent and received on the TSI/PCM interface is 8-bit PCM
A-law.
The drift information is distributed via a dedicated TSI slot as specified in section 6.6.5
on page 6-30. The drift information is constructed by a 3 byte frame and is distributed
to the integrator periodically every 4
th
second if distribution of at least one of the drift
parameters has been enabled as per section 6.6.5 on page 6-30.
Example: Check sum calculation
ID = 5, Clock drift (byte 2) = 0x45, CS fifo drift (byte 3) = 0xC4
Check Sum = 16 - ((5+4+5+12+4)%16) = 2
Byte 1 = 0x52, byte 2 = 0x45, byte 3= 0xC4
7.9.3 Configuring the TSI/PCM interface for test mode operation
The TSI/PCM interface may be configured for loopback test. This is described in detail
in section 11.3.4 on page 11-9.
Byte 1 Byte 2 Byte 3
ID (7..4) Check sum (3..0) Clock drift CS fifo drift
Table 7-31: Drift information format (3 bytes)
Data field Type Bits Value Comment
ID U4 7..4 0..15 0x0 - not valid.
0x1 .. 0x4 reserved
0x5 - Clock adjust
0x6 .. 0xf reserved.
Check sum U4 3..0 0..15 The result of an unsigned addition off all nibbles
including checksum must give a 4bit result = 0. See
example below.
Clock drift S8 7..0 -128..
127
Contains the clock drift information (if enabled, otherwise
0). Signed value x 0.0625 ppm
CS fifo drift S8 7..0 -128..
127
Contains the CS fifo drift information (if enabled,
otherwise 0). Signed value x 0.0625 ppm
Table 7-32: Drift information frame content