National Instruments AT-MIO-16X User Manual
Page 188
Chapter 5
Programming
© National Instruments Corporation
5-19
AT-MIO-16X User Manual
1.
Write FF04 to the Am9513A Command Register to select the
Counter 4 Mode Register.
2.
Write 1025 to the Am9513A Data Register to store the Counter 4
mode value for posttrigger acquisition modes. Write 9025 to the
Am9513A Data Register to store the Counter 4 mode value for
pretrigger acquisition modes.
3.
Write FF0C to the Am9513A Command Register to select the
Counter 4 Load Register.
4.
Write the 16 LSBs of the sample count value minus 1 to the
Am9513A Data Register to store the Counter 4 load value.
–
If the 16 LSBs are all 0, write FFFF.
5.
Write FF48 to the Am9513A Command Register to load Counter 4.
6.
Write 0 to the Am9513A Data Register to store 0 into the Load
Register for Counter 4 reloading.
7.
Write FF28 to the Am9513A Command Register to arm Counter 4.
8.
Write FF05 to the Am9513A Command Register to select the
Counter 5 Mode Register.
9.
Write 25 to the Am9513A Data Register to store the Counter 5
mode value.
10. Write FF0D to the Am9513A Command Register to select the
Counter 5 Load Register.
11. Take the 16 MSBs of the sample count and complete the following
steps:
–
If the 16 LSBs of the sample count are all 0 or all 0 except for
a 1 in the LSB, write the 16 MSBs to the Am9513A Data
Register to store the Counter 5 load value.
–
Otherwise, add 1 to the 16 MSBs of the sample count and write
that value to the Am9513A Data Register to store the Counter 5
load value.
12. Write FF70 to the Am9513A Command Register to load and arm
Counter 5.
13. Set the CNT32/16* 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 decrements every time Counter 4 reaches zero. The data