Yoctopuce Yocto-GPS, User Manual

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// Next calls to loadMore() will retrieve measures
Console . WriteLine ( "loading details" ) ;
int progress;
do {
Console . Write ( "." ) ;
progress = dataset. loadMore () ;
} while( progress < 100 ) ;
// All measures have now been loaded
List<YMeasure> details = dataset. get_measures () ;
foreach ( YMeasure m in details ) {
Console . WriteLine ( String. Format ( logFmt,
m. get_startTimeUTC_asDateTime () . ToString ( timeFmt ) ,
m. get_endTimeUTC_asDateTime () . ToString ( timeFmt ) ,
m. get_averageValue () , sensor. get_unit ())) ;
}
You will find a complete example demonstrating how to retrieve data from the logger for each
programming language directly in the Yoctopuce library. The example can be found in directory
Examples/Prog-DataLogger .
Timestamp
As the Yocto-GPS does not have a battery, it cannot guess alone the current time when powered on.
Nevertheless, the Yocto-GPS will automatically try to adjust its real-time reference using the host to
which it is connected, in order to properly attach a timestamp to each measure in the datalogger:
• When the Yocto-GPS is connected to a computer running either the VirtualHub or any
application using the Yoctopuce library, it will automatically receive the time from this
computer.
• When the Yocto-GPS is connected to a YoctoHub-Ethernet, it will get the time that the
YoctoHub has obtained from the network (using a server from
pool.ntp.org
)
• When the Yocto-GPS is connected to a YoctoHub-Wireless, it will get the time provided by the
YoctoHub based on its internal battery-powered real-time clock, which was itself configured
either from the network or from a computer
• When the Yocto-GPS is connected to an Android mobile device, it will get the time from the
mobile device as long as an app using the Yoctopuce library is launched.
When none of these conditions applies (for instance if the module is simply connected to an USB
charger), the Yocto-GPS will do its best effort to attach a reasonable timestamp to the measures,
using the timestamp found on the latest recorded measures. It is therefore possible to "preset to the
real time" an autonomous Yocto-GPS by connecting it to an Android mobile phone, starting the data
logger, then connecting the device alone on an USB charger. Nevertheless, be aware that without
external time source, the internal clock of the Yocto-GPS might be be subject to a clock skew
(theoretically up to 0.3%).
17.3. Sensor calibration
Your Yocto-GPS module is equipped with a digital sensor calibrated at the factory. The values it
returns are supposed to be reasonably correct in most cases. There are, however, situations where
external conditions can impact the measures.
The Yoctopuce API provides the mean to re-caliber the values measured by your Yocto-GPS. You
are not going to modify the hardware settings of the module, but rather to transform afterwards the
measures taken by the sensor. This transformation is controlled by parameters stored in the flash
memory of the module, making it specific for each module. This re-calibration is therefore a fully
software matter and remains perfectly reversible.
Before deciding to re-calibrate your Yocto-GPS module, make sure you have well understood the
phenomena which impact the measures of your module, and that the differences between true
values and measured values do not result from a incorrect use or an inadequate location of the
module.
17. Advanced programming
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