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MT90500
109
Table 67 - DIVX Register
Address: 60A8 (Hex)
Label: DIVX
Reset Value: 2000 (Hex)
Label
Bit Position
Type
Description
DIVX
13:0
R/W
This value is used (along with DIVXN, in the next register) to divide MCLK to obtain an
RXVCLK reference. The average frequency of RXVCLK is obtained as follows:
Note that when a new RXVCLK setting requires a change to this register and to the DIVX
Ratio Register, these two writes should be performed as closely together as possible. This
is required to prevent drifting of the REF8KCLK output frequency during the period that
one register has been updated but the other hasn’t.
Reserved
15:14
R/W
Reserved. Should be written as “00”.
Table 68 - DIVX Ratio Register
Address: 60AA (Hex)
Label: DIVXR
Reset Value: 0FFF (Hex)
Label
Bit Position
Type
Description
DIVXN
11:0
R/W
This value defines how many times MCLK will be divided by (DIVX + 2) and how many
times it will be divided by (DIVX + 3), as per the formula shown in 60A8h above. When
001h, MCLK is divided by (DIVX + 2) once, then divided 4095 times by (DIVX + 3).
Note: 0 is an illegal value for DIVXN (same ratio as 1)
Reserved
15:12
R/W
Reserved. Should be written as “0000”.
Table 69 - SRTS Transmit Gapping Divider Register
Address: 60B0(Hex)
Label: SRTGD
Reset Value: 0000 (Hex)
Label
Bit Position
Type
Description
TX_Gapping
7:0
R/W
This field provides the separation between consecutive pulses of the f
B
clock. This field
should be set according to the following formula: (256 / number of channels per VC) - 1.
The result must be rounded down.
1 channel -> 255
2 channels -> 127
3 channels -> 84
...
TX_Ch_per_VC
14:8
R/W
Number of channels in the VC that is selected for transmitting the SRTS.
0h -> 1 channel
1h -> 2 channels
...
79h -> 122 channels
Note:
Since maximum number of channels per VC is 122, values 7A:7F are reserved.
Reserved
15
R/W
Reserved. Should be written as ‘0’.
RXVCLKavg
MCLK
-------------------+
DIVXN
DIVX
4096
3
+
)
4096
DIVXN
–
(
)
×
+
------------------------------------------------------------------1
×
=