VXI SVM2608, Руководство пользователя

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SVM2608 Programming 51
E
XAMPLES
Example 1: Setting the Channel 2 and 4 Sample Rate to 123 ms (8.13 kHz)
The sample rate clock for an individual low-speed channel (Channels 0 – 3) is generated by
dividing a 0.1 µs (10 MHz) reference clock, generated by an on-board oscillator, by the value
present in the Sample Rate register of the respective channel. For the high-speed channels
(Channels 4 – 5), the reference clock is 8.333 ns (120 MHz).
123 ms = 123*10
-3
s
For Channel 2, divide 123 ms by the 0.1 µs reference clock:
000 , 230 , 1
s 10 100
s 10 123
9
-3
=
×
×
−
For Channel 4, divide 123 ms by the 8.333 ns reference clock:
14,760,590
s 10 333 . 8
s 10 123
9
-3
≅
×
×
−
To set the Sample Rate to 123 ms, the reference clock must be divided by 1,230,000 for Channel 2
and 14,760,590 for Channel 4. In hexadecimal format, these values correspond to 0x12C4B0 and
E13A8E, respectively. The Sample Rate register for Channel 2 is composed of two 16 bits
registers located at offsets 0xC0005C (the MS – Most Significant bits, bits D24 - 16) and
0xC0005E (the LS – Least Significant bits, bits D15 - D0). The Sample Rate register for Channel
4 is similar, starting at offset 0xAC.
Method 1 : Make two 16 bits writes.
For low-speed Channel 2:
Write 0x0012 to Base a 0xC0005C
Write 0xC4B0 to Base a 0xC0005E
For high-speed Channel 4:
Write 0x00E1 to Base a 0xC000AC
Write 0x3A8E to Base a 0xC000AE
Method 2 : Make one 32 bits write.
For low-speed channels 0 – 3:
Write 0x0012C4B0 to Base a 0xC0005C
For high-speed channels 4 – 5:
Write 0x00E13A8E to Base a 0xC000AE
Example 2: Setting Channel 2 to Acquire 200,000 Samples
The number of samples acquired in Linear mode by a channel is determined by the value
programmed in the Sample Points register of the respective channel. In hexadecimal format,
200,000 corresponds to 0x30D40. The Sample Points register for Channel 2 is composed of two
16-bit registers located at offsets 0xC00060 (the MS, bits D19 - D16) and 0xC00062 (the LS, bits
D15 - D0).
Method 1 : Make two 16 bits writes.
Write 0x0003 @ Base a 0xC00060