Programming
Chapter 4
AT-MIO-16D User Manual
4-60
© National Instruments Corporation
After you complete this programming sequence, Counter 4 is configured to count A/D
conversion pulses generated by Counter 3 and turns off the data acquisition operation when
Counter 4 reaches zero.
Sample Counts Greater Than 65,536. To program the sample counter for sample counts greater
than 65,536, use the following programming sequence. The lower 16 bits of the sample count
are stored in Counter 4, and the upper 16 bits of the sample count are stored in Counter 5. All
writes are 16-bit operations. All values given are hexadecimal.
a.
Write FF04 to the Am9513A Command Register to select the Counter 4 Mode Register.
b.
Write 1025 to the Am9513A Data Register to store the Counter 4 mode value.
c.
Write FF0C to the Am9513A Command Register to select the Counter 4 Load Register.
d.
Write the least significant 16 bits of the sample count value minus 1 to the Am9513A Data
Register to store the Counter 4 load value.
•
If the least significant 16 bits are all zero, write FFFF.
e.
Write FF48 to the Am9513A Command Register to load and arm Counter 4.
f.
Write 0 to the Am9513A Data Register to store 0 into the Load Register for Counter 4
reloading.
g.
Write FF28 to the Am9513A Command Register to arm Counter 4.
h.
Write FF05 to the Am9513A Command Register to select the Counter 5 Mode Register.
i.
Write 25 to the Am9513A Data Register to store the Counter 5 mode value.
j.
Write FF0D to the Am9513A Command Register to select the Counter 5 Load Register.
k.
Take the most significant 16 bits of the sample count and do the following:
•
If the least significant 16 bits of the sample count are all zeros or all zeros except for a 1
in the least significant bit, write the most significant 16 bits to the Am9513A Data
Register to store the Counter 5 load value.
•
Otherwise, add 1 to the most significant 16 bits of the sample count and write that value
to the Am9513A Data Register to store the Counter 5 load value.
l.
Write FF70 to the Am9513A Command Register to load and arm Counter 5.
m. Set the 16*/32 CNT bit in Command Register 1 to notify the hardware that both Counters 4
and 5 will be used as the sample counter.
After you complete this programming sequence, Counter 4 is configured to count A/D
conversion pulses generated by Counter 3, and Counter 5 increments every time Counter 4
reaches zero. The data acquisition operation terminates when both Counters 4 and 5 reach zero
and the last entry in the mux-gain memory is served.
Содержание AT-MIO-16D
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