National Instruments AT-MIO-64F-5, Руководство пользователя

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Calibration Procedures Chapter 6
AT-MIO-64F-5 User Manual 6-4 © National Instruments Corporation
0 1 2
7
3 4 5 6
ADC FIFO Length DAC FIFO Length
LSB MSB
0110 = 16,384
0010 = 1,024
0001 = 512
0000 = 256
0101 = 8,192
0100 = 4,096
0011 = 2,048
0110 = 16,384
0010 = 1,024
0001 = 512
0000 = 256
0101 = 8,192
0100 = 4,096
0011 = 2,048
Figure 6-4. ADC and DAC FIFO Depth Field
If the ADC and DAC FIFO Depth Field contains the binary value 00010011, then the
AT-MIO-64F-5 board that was accessed contains an ADC FIFO buffer of depth 512 and a DAC
FIFO buffer of depth 2,048. This information is extremely useful in determining how many
values to read from the ADC FIFO or write to the DAC FIFO when a half-full interrupt is
generated. For example, if it is known that the ADC FIFO is 512 values deep and a half-full
interrupt is generated, then 256 values can be read in at once without checking the Status
Register 0 to see if the FIFO contains values.
Alternately, if the DAC FIFO is 2,048 values deep and a half-full interrupt is generated, then
1,024 values can be read. This can have a significant performance impact on software speed.
••
0 1 2 7 3 4 5 6
Reserved
Reserved
Reserved
Reserved
Reserved
DAC1 Range
DAC0 Range
ADC Range
LSB MSB
Figure 6-5. Area Information Field
If the Area Information Field contains the binary value XXXXX10X where X indicates don't
care bits, then the area described by this area information value contains bipolar DAC 1
calibration constants and unipolar DAC 0 calibration constants; thus a 1 indicates bipolar and
a 0 indicates unipolar. The area information value for the factory bipolar area will always be
XXXXX11X, and for the factory unipolar area it will always be XXXXX00X. If the analog
output section is calibrated using the library functions and the constants are saved to an
EEPROM area, then the area information bits will be set according to the mode in which the
analog output section was calibrated. The analog input section is calibrated in both unipolar and
bipolar modes, so you do not need to recalibrate this section when the mode changes.