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trying to improve calibration docs

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Frank Mori Hess 2003-12-03 02:43:22 +00:00
parent 217924bcfe
commit a03c337cdb
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@ -846,9 +846,40 @@ Status: alpha
Description:
This function sets the calibration of the specified subdevice
so that it is in proper calibration when using the specified
channel, range and aref. Depending on the hardware, the
channel, range and aref. It does so by performing writes
to the appropriate channels of the board's calibration
subdevice(s). Depending on the hardware, the
calibration settings used may or may not depend on the channel,
range, or aref. The file_path parameter can be used
range, or aref. Furthermore, the calibrations for different
channels, ranges, or arefs may not be independent.
For example, some boards cannot have their analog inputs calibrated
for multiple input
ranges simultaneously. Applying a calibration for range 1 may
blow away a previously applied calibration for range 0. Applying
a calibration for analog input channel 0 may cause the same
calibration to be applied to all the
other analog input channels as well.
Your only guarantee is that calls to comedi_apply_calibration()
on different subdevices will not interfere with each other.
In practice, their are some rules of thumb on how
calibrations behave. No calibrations depend on the aref.
A multiplexed analog input will have calibration settings that
do not depend on the channel, and applying a setting for one
channel will affect
all channels equally. Analog outputs, and analog inputs
with independent a/d converters for each input channel, will have
calibrations settings which do depend on the channel, and the
settings for each channel will be independent of the other
channels.
If you wish to investigate exactly what comedi_apply_calibration()
is doing, you can perform reads on your board's calibration
subdevice to see which calibration channels it is changing.
You can also try to decipher the calibration file directly (it's a
text file).
The file_path parameter can be used
to specify the file which contains the calibration information.
If <parameter>file_path</parameter> is NULL, then comedilib
will use a default