hi farley,
the format of the file is a repeated tuple of (accelx, accely, accelz)
binary 16-bit integers.
the file contains no timestamp. CURRENT_TIME is used to orient the
filesystem so that it has some idea of reality when it dates the files;
it's the standard unix time, or "seconds since epoch" (that's jan 1,
1970 0000 UTC). size is time_t, or 32 bits unsigned.
if you want runtime-current timestamps, then you need to run the
companion version of this app hosttimelogging, which is in an adjacent
directory. that uses the host machine to set the shimmer's time while
in the dock, and it will be persistent between resets (yes, programming
resets the device).
i hope that this helps,
steve
On 06/19/2012 10:05 AM, Farley Lai wrote:
Hi, all,
I built and ran JustFATLogging on the Shimmer2r motes. However, I have
questions about the format of the binary data saved by JustFATLogging.
1. what is the endian of the unsigned values and timestamps?
2. the system time in seconds seems greater than 16bits. If we set the
CURRENT_TIME to build the program, what is the size of the timestamp
in bytes the application will write to the storage?
I assume everything is unsigned 16bit little-endian integers and print
the start of the first saved binary file (000) in the format "timestamp,
(x, y, z)".
ts: 2194, (1929, 2798, 2209)
ts: 1949, (2826, 2198, 1959)
ts: 2783, (2257, 1950, 2745)
ts: 2274, (1915, 2828, 2265)
The CURRENT_TIME is set to about 1340092314.0. Nonetheless, I cannot see
anything to do with the time. Could anybody help clarify this?
Thanks.
Farley
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