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Update Battery Benchmark plugin in the manual to correct some out-of-date

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information, and rewrite some sections to improve the English.


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@20352 a1c6a512-1295-4272-9138-f99709370657
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Alex Parker 2009-03-18 22:37:24 +00:00
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97
manual/plugins/batterybenchmark.tex
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@ -1,20 +1,19 @@
\subsection{Battery Benchmark}
The Battery Benchmark Plugin enables you to test your battery's performance,
while making normal use of your \dap. Once loaded it will run in the
background (TSR plugin), reading various info about your battery while you use
it. Once you finish your session you can find the benchmark output data in a
file on your \dap\ \fname{/battery\_bench.txt}.
Please submit your results to the Rockbox wiki.
\wikilink{BatteryRuntime}
The \setting{Battery Benchmark} plugin enables you to test your battery's
performance whilst using your \dap\ normally. Results can be submitted
to the \wikilink{BatteryRuntime} wiki page.
\subsubsection{How it works}
After you load the plug-in the operation of your \dap\ continues as normal.
You can do whatever you could do before loading the plugin except loading
another plugin. If you happen to load a plugin while benchmarking, a splash
screen will inform you about the termination of the benchmark.
While you operate it will log various battery related information every time
the disk is activated by external causes, (buffer refill, open directory,
USB mode) or an hour passes without updating the log file.\\
Once loaded, \setting{Battery Benchmark} runs in the
background recording various information about your battery to memory.
A new point is written to memory every minute.
Every time the disk is accessed for any reason
(such as refilling the audio buffer, opening a directory or entering
USB mode etc.) then the information in memory is written to disk.
Once the memory becomes full (after many hours), then the data
are written to disk anyway. This is done so that the data are not biased by
excessive additional disk accesses. The file is written to the root
directory of your \dap\ and is called \fname{battery\_bench.txt}.
The plugin will continue to log info until:
\begin{itemize}
@ -22,49 +21,43 @@ The plugin will continue to log info until:
\item The \dap\ is shut down.
\item The battery is empty.
\end{itemize}
Between disk activity (or an hour), it will log info in memory (every
measurement is captured when the voltage changes). If there are too many
measurements older entries will be deleted and the log file will inform the
user about the interval where entries were lost. Benchmarks can be resumed if
you accidentally load a plugin, or turn off your \dap, as long as the log
file \fname{/battery\_bench.txt} is not deleted.
Benchmarks can be resumed if
you accidentally load a plugin, or turn off your \dap, so long as the log
file \fname{battery\_bench.txt} is not deleted.
\subsubsection{Information explained}
On the top of the file you will see various info on how to use the plugin.
At the top of the \fname{battery\_bench.txt} file is various
information on how to use the plugin, followed by the data themselves.
\begin{description}
\item[Time] This column reports the total time of operation of the \dap. It is
not the time that you started the plug-in. If you have your player on for 5
not the time that you started the plug-in. If you have your \dap\ on for 5
minutes and then start the plugin, it will start measuring from 5 minutes.
\item[Seconds] As time, it shows time passed in seconds. Nothing special, it is
there because it is free and maybe someone might want to make graphs with
seconds.
\item[Level] The percent level of the battery estimated by Rockbox. This is an
estimation and not an accurate result. Using the real percentage (current
battery voltage / top battery voltage) * 100) we can calculate the difference
between the estimation. Goal of this column is to make the estimation algorithm
of Rockbox more accurate.
\item[Time Left] It shows the estimated (by Rockbox) remaining time until
shutdown. Again, as with Level(above), this column can be used to see
differences between real time left and estimated time left. This could help
make time left more accurate.
\item[Voltage] The battery voltage, the moment the measurement was captured.
Measurements are captured when this number changes while benchmarking.
This column can be used to give quite interesting graphs in a spreadsheet
program. (Excel, Calc, e.t.c)
\item[M/DA] (Measurements per Disk Activity) The number of measurements stored
temporarily in memory, before written on the log file. This can give you an
idea of how many voltage changes there are between disk activity (or one hour).
\item[C] Stands for Charger. An "A" in that column shows if there was the power
adapter attached to the unit, at the time of the measurement.
\item[S] The "S" column shows the state of the device (Charging, or not). The
"C" indicated that the unit was charging when the measurement was captured.
\item[Seconds] The same as \config{Time}, except measured in seconds.
\item[Level] The percent level of the battery estimated by Rockbox, and not the
actual battery level. The actual battery level can be seen from the
\config{Voltage} column
\item[Time Left] This shows the time remaining until the battery is empty,
again as estimated by Rockbox.
\item[Voltage] The battery voltage in mV at the moment the measurement
was taken.
\item[C] This stands for Charger. An "A" in that column shows if the power
adapter was attached to the unit at the time of the measurement.
\item[U] USB powered. Only for targets that support this. A "U" will indicate
if the unit was using the USB port for powering.
if the unit was using the USB port for power at the time of the measurement.
\end{description}
\subsubsection{Making graphs}
While you can tell how long your battery lasted, with a single look at the last
line of the battery log (\fname{/battery\_bench.txt}), the most useful purpose of
Battery Benchmark is to make graphs using a spreadsheet program like Excel or
Calc. The battery log (\fname{/battery\_bench.txt}) is in CSV format (comma separated)
so you can quite easily import it to a spreadsheet program.
\subsubsection{Usage}
The log file can be used to tell you how long the battery lasted (with some
limitations, see below), but it is most useful for graphing discharge curves
in order to improve Rockbox's estimation of battery level and time remaining.
The battery log (\fname{battery\_bench.txt}) is in CSV format
(comma separated variables) and thus can be easily imported into a spreadsheet
or similar program.
\subsubsection{Limitations}
As \setting{Battery Benchmark} needs to write the data held in memory to
disk in order to save them, it is possible that should Rockbox shut down
due to low battery then there will not be enough power remaining to write the
data to disk. Therefore all measurements since the previous save will be lost.