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DS3171/DS3172/DS3173/DS3174
65
Table 10-12. Global 8 kHz Reference Source Table
G8KIS
G8KRS[2:0]
Source
0
000
None, the 8KHZ divider is disabled.
0
001
Derived from CLAD DS3 clock output or CLKA pin if CLAD
is disabled. (Note: CLAD is disabled after reset)
0
010
Derived from CLAD E3 clock output or CLKB pin if CLAD is
disabled
0
011
Derived from CLAD STS-1 clock output or CLKC pin if CLAD
is disabled
0
100
Port 1 8KREF source selected by P8KRS[1:0]
0
101
Port 2 8KREF source selected by P8KRS[1:0]
0
110
Port 3 8KREF source selected by P8KRS[1:0]
0
111
Port 4 8KREF source selected by P8KRS[1:0]
1
XXX
GPIO4 pin
lists the selectable sources for port 8 kHz reference sources.
Table 10-13. Port 8 kHz Reference Source Table
.P8KRS[1:0] Source
0X Undefined
10
Internal receive framer clock
11
Internal transmit framer clock
The 8 kHz reference logic tree is shown below.
Figure 10-7. 8KREF Logic
0
1
CLOCK DIVIDER
0
1
CLOCK DIVIDER
0
1
1
3
2
1
3
2
0
TX CLOCK
RX CLOCK
FRAME MODE
P8KRS
GPIO4
OTHER
PORT
8KREF
DS3 CLK
E3 CLK
CC52 CLK
FROM CLAD
G8KRS[1:0]
G8KRS[1:0]
G8KRS[2]
G8KREF
GLOBAL 8KREF
PORT 8KREF