USB Accelerometer Model X16-1C
3.2.6
Real Time Clock
A real time clock (RTC) is integrated into the X16-1C system and is used to determine time for each
line of data recorded. The RTC maintains
±
2ppm accuracy (0°C to +40°C) and is powered by the
primary battery. The RTC will reset if the battery is removed or depleted. The RTC also provides the
system temperature (°C) recorded to the header of each data file.
The RTC is set using a text file named “time.txt” located in the root directory of the microSD card.
The system looks for the time.txt file upon booting. If the file exists, the time stored in the file is
loaded to the RTC and the time.txt file is deleted. The time information in the time.txt file must be in
the exact “yyyy-MM-dd HH:mm:ss” 24-hour format, occur on the first line, and end with a newline
character. The time file method of setting the RTC does not require special communication drivers so
it can be implemented using any text editor. Direct initialization of the RTC is possible but requires
specific device drivers from Gulf Coast Data Concepts.
3.2.7
Memory Card
The X16-1C stores data to a removable 2GB microSD flash memory card. The device operates using
FAT16 file structure, which limits the maximum microSD card capacity to 2GB. The “config.txt” and
“time.txt” files must occur in the root directory (see section 3.2.4 and section 3.2.6). The X16-1C
functions as a Mass Storage Device to computer operating systems when transferring data to and from
the microSD memory card.
The X16-1C is compatible with microSD and microSDHC type cards but the card must be formatted to
FAT16 for proper operation of the X16-1C. Under Windows XP, the card must be formatted using the
“FAT” file system and the default allocation size. Do not select “Quick Format” or “FAT32”. The
X16-1C will create a folder called “GCDC”, if not already present, to place the data files (see section
3.2.5).
January 2012 Rev New
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