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M2i.30xx / M2i.30xx-exp Manual
External clocking
Clock generation
External clocking
Direct external clock
An external clock can be fed in on the external clock connector of the board. This can be any clock, that matches the specification of the
card. The external clock signal can be used to synchronize the card on a system clock or to feed in an exact matching sampling rate.
The maximum values for the external clock is board dependant and shown in the table below.
Termination of the clock input
If the external connector is used as an input, either for feeding in an external reference clock or for external clocking you can enable a
50 Ohm termination on the board. If the termination is disabled, the impedance is high. Please make sure that your source is capable of
driving that current and that it still fulfills the clock input specification as given in the technical data section.
Minimum external sample rate
The minimum external sample rate is limited on all boards to 1 MHz and the maximum sample rate depends on the specific type of board.
The maximum sample rates for your type of board are shown in the tables below.
Maximum external sampling rate in MS/s
An external sample rate above the mentioned maximum can cause damage to the board.
The following table shows the available ranges when using external clocking:
The range must not be left by more than 5% when the board is running. Remember that the ranges depend
on the activated channels as well, so a different board setup for external clocking must always include the
related clock ranges.
This table below shows the ranges that are defined by the two range registers mentioned above. The range depends on the activated channels
per module. For details about what channels of your specific type of board is located on which module, please take a look at the according
introduction chapter. Please be sure to select the correct external range, as otherwise it is possible that the card will not run properly.
Register
Value
Direction
Description
SPC_CLOCKMODE
20200
read/write
Defines the used clock mode
SPC_CM_EXTERNAL
8
Enables external clock input for direct sample clock generation
Register
Value
Direction
Description
SPC_CLOCK50OHM
20120
read/write
A „1“ enables the 50 Ohm termination at the external clock connector. Only possible, when using
the external connector as an input.
activated Channels
M2
i.
30
10
M2
i.
30
11
M2
i.
30
12
M2
i.
30
13
M2
i.
30
14
M2
i.
30
15
M2
i.
30
16
M2
i.
30
20
M2
i.
30
21
M2
i.
30
22
M2
i.
30
23
M2
i.
30
24
M2
i.
30
25
M2
i.
30
26
M2
i.
30
27
M2
i.
30
31
M2
i.
30
33
Ch0
Ch1
Ch2
Ch3
X
80
40
80
40
80
80
80
105
50
105
50
105
105
105
105
62.5
62.5
X
n.a.
40
80
40
80
80
80
n.a.
50
105
50
105
105
105
105
62.5
62.5
X
n.a.
n.a.
n.a.
40
80
n.a.
80
n.a.
n.a.
n.a.
50
105
n.a.
105
n.a.
n.a.
62.5
X
n.a.
n.a.
n.a.
40
80
n.a.
80
n.a.
n.a.
n.a.
50
105
n.a.
105
n.a.
n.a.
62.5
X
X
n.a.
40
40
40
40
80
40
n.a.
50
50
50
50
105
50
105
62.5
62.5
X
X
n.a.
n.a.
n.a.
40
80
n.a.
80
n.a.
n.a.
n.a.
50
105
n.a.
105
n.a.
n.a.
62.5
X
X
n.a.
n.a.
n.a.
40
80
n.a.
80
n.a.
n.a.
n.a.
50
105
n.a.
105
n.a.
n.a.
62.5
X
X
n.a.
n.a.
n.a.
40
80
n.a.
80
n.a.
n.a.
n.a.
50
105
n.a.
105
n.a.
n.a.
62.5
X
X
n.a.
n.a.
n.a.
40
80
n.a.
80
n.a.
n.a.
n.a.
50
105
n.a.
105
n.a.
n.a.
62.5
X
X
n.a.
n.a.
n.a.
40
40
n.a.
40
n.a.
n.a.
n.a.
50
50
n.a.
50
n.a.
n.a.
62.5
X
X
X
X
n.a.
n.a.
n.a.
40
40
n.a.
40
n.a.
n.a.
n.a.
50
50
n.a.
50
n.a.
n.a.
62.5
Register
Value
Direction
Description
SPC_EXTERNRANGE
20130
read/write
Defines the range of the actual fed in external clock. Use one of the below mentioned ranges
EXRANGE_LOW
64
External range for slower clocks
EXRANGE_HIGH
128
External range for faster clocks
For cards with 8 bit converter resolution
For cards with 12, 14, 16 bit converter resolution
Activated Channels
on one module
EXRANGE_LOW
EXRANGE_HIGH
EXRANGE_LOW
EXRANGE_HIGH
1
< 50.0 MHz
>= 50.0 MHz
< 50.0 MHz
>= 50.0 MHz
2
< 50.0 MHz
>= 50.0 MHz
< 25.0 MHz
>= 25.0 MHz
4
< 25.0 MHz
>= 25.0 MHz
< 12.5 MHz
>= 12.5 MHz
8
< 12.5 MHz
>= 12.5 MHz
< 6.0 MHz
>= 6.0 MHz
