Skip to content

S
Software for White Rabbit PTP Core
Commit f9020875 authored by Adam Wujek's avatar Adam Wujek
Browse files
Options

doc: add documentation for insitu calibration 

Signed-off-by: 's avatarAdam Wujek <dev_public@wujek.eu>
parent 0bb5edb9
Pipeline #4045 passed with stage
    in 1 minute and 31 seconds
    Hide whitespace changes
    Inline Side-by-side
    Showing with 385 additions and 0 deletions
    doc/wrpc.tex
    View file @ f9020875
    ......@@ -21,6 +21,7 @@
    \usepackage{multirow}
    \usepackage[toc]{appendix}
    \newcommand{\newparagraph}[1]{\paragraph{#1}\mbox{}\\}
    \usepackage{placeins}
    \definecolor{wrlblue}{RGB}{165,195,210}
    \definecolor{wrlgray}{RGB}{209,211,212}
    ......@@ -2836,6 +2837,283 @@ make
    \end{lstlisting}
    The output will be copied to the specified \texttt{<install\_dir>}.
    % --------------------------------------------------------------------------
    \newpage
    \section{In-situ calibration}
    \label{appendix:insitu}
    This section describes how to configure and use insitu calibration in WRPC.
    \subsection{In-situ configuration}
    To configure all needed means for in-situ calibration, make sure the option
    \texttt{CONFIG\_INSITU\_CALIB} and \texttt{CONFIG\_CMD\_SFP\_INFO} are selected
    in the dot-config.
    Enabling this configuration options has number of side effects.
    It adds the following commands:
    \begin{lstlisting}
    sfp tune <channel|wavelength>
    insitu <on|off|crtt|run|stop>
    ptp sync_int <n>
    ptp delay_req_int <n>
    ptrack insitu
    \end{lstlisting}
    The output of the command \texttt{sfp info} is extended by extra information
    specific to tunable SFPs:
    \begin{lstlisting}
    SFP tunable: true
    Dither TX: false
    Tunable by channel: true
    Tunable by wavelength: true
    Laser first freq: 191.7000 THz
    Laser last freq: 196.1000 THz
    Laser's grid support: 50.0 GHz
    Channels supported: 1..89
    Current channel number: 1
    Current wavelength: 1563.85 nm
    \end{lstlisting}
    \subsection{Getting timestamps}
    This subsection describes obligatory and optional steps to get input for further
    calculations.
    As a first step it is recommended to disable the assymetry of a link. It can be
    done by setting alpha to 0 for the used SFP in the local database.
    To achieve this, get the Vendor PN of the SFP by:
    \begin{lstlisting}
    wrc# sfp info
    [...]
    Vendor PN: FTLX6872MCC
    [...]
    \end{lstlisting}
    Then add it to the SFPs database:
    \begin{lstlisting}
    wrc# sfp add FTLX6872MCC 200000 300000 0 0
    \end{lstlisting}
    Please note that in this example deltas are set to an example values. Last two
    zeros set the alpha to 0 (disable assymetry).
    The second optional step is to avoid White Rabbit synchronization, only layer-1
    syntonization will be used.
    This can be done with the command:
    \begin{lstlisting}
    ptrack insitu
    \end{lstlisting}
    This can reduce the time between start the procedure and printout of usable data.
    It is useful to run this command before the regular synchronization happens.
    The next optional step is to configure SFP to the desired channel or
    wavelength for transmission using the \texttt{sfp tune} command:
    \begin{lstlisting}
    sfp tune <channel|wavelength>
    \end{lstlisting}
    For example to set wavelength to 1563.85nm:
    \begin{lstlisting}
    sfp tune 1563.85
    \end{lstlisting}
    To get the t1-t4 timestamps please execute the following command:
    \begin{lstlisting}
    insitu on
    \end{lstlisting}
    This will give the output to the console like:
    \begin{lstlisting}
    t1t2: 1661513034.690862958848 3030.150239945501
    t3t4: 3030.189306224000 1661513034.729982850925
    t1t2: 1661513035.526964302848 3030.986341289504
    t3t4: 3031.966333168000 1661513036.507009794932
    \end{lstlisting}
    Alternatively the calculations of the round trip time can be done on WRPC
    with the addition to the delta correction. To display these values instead
    execute the command:
    \begin{lstlisting}
    insitu crtt
    \end{lstlisting}
    This will give an example output:
    \begin{lstlisting}
    t3t4t2t1: 0.000053613578
    t3t4t2t1: 0.000053613573
    t3t4t2t1: 0.000053613578
    \end{lstlisting}
    If needed the rate of issuing delay-request messages can be changed with
    a command:
    \begin{lstlisting}
    ptp delay_req_int <n>
    \end{lstlisting}
    Parameter\texttt{n} is a logarithm to the base 2 of the mean interval of delay
    request message transmission.
    In practice it affects the rate of t3-t4 printouts or round trip time corrected
    with deltas, based on what is to be printed.
    To wrap up this section, as an example the following commands can be executed
    to get the round trip times every 500ms using channel 1 of SFP:
    \begin{lstlisting}
    ptrack insitu
    sfp tune 1
    ptp delay_req_int -1
    insitu crtt
    \end{lstlisting}
    The delays similar to the below will start appearing on the console:
    \begin{lstlisting}
    t3t4t2t1: 0.000053613578
    t3t4t2t1: 0.000053613573
    t3t4t2t1: 0.000053613578
    \end{lstlisting}
    \subsection{Sweep over many channels}
    It is possible to sweep over several SFP's channels in one go with a command:
    \begin{lstlisting}
    insitu run <ch_start> <ch_end> <step> <samples>
    \end{lstlisting}
    Where:
    \begin{itemize*}
    \item \texttt{ch\_start} is the first channel to be set
    \item \texttt{ch\_end} is the last channel to be set
    \item \texttt{step} defines the increment of channel
    \item \texttt{samples} defines number of delay-response messages to be
    collected for each channel
    \end{itemize*}
    The following command run the test for channels 1, 3, 5, 7.
    Change of a channel will happen after 100 of t3-t4 timestamps is collected.
    The presence and the format of timestamps can be changed with
    the \texttt{insitu} command.
    \begin{lstlisting}
    insitu run 1 7 2 100
    \end{lstlisting}
    After this command is triggered it is possible to request printout of
    round trip time corrected with deltas instead of t1-t4 timestamps.
    It can be done with a command:
    \begin{lstlisting}
    insitu crtt
    \end{lstlisting}
    The sweep can generate a significant amount of data to the console.
    The output of the virtual console can be redirected to a file by e.g. command:
    \begin{lstlisting}
    $ ./spec-vuart 2>&1 | tee output_file.txt
    \end{lstlisting}
    \subsection{Combining results into a plot}
    Scripts used in this subsection can be found in the directory
    \texttt{tools/insitu} in \textit{wrpc-sw} repository.
    If wrpc is configured to output t1-t4 timestamps,
    the \texttt{insitu\_process\_data.py} script can be used to calculate one way
    time difference and round trip time
    (please note that it is not corrected with delta values).
    \begin{lstlisting}
    $ ./insitu_process_data.py output_file.txt
    \end{lstlisting}
    Script will generate files:
    \begin{itemize*}
    \item \texttt{output\_file.txt.t1} -- with columns: \texttt{t1}, \texttt{t2},
    \texttt{t2-t1}
    \item \texttt{output\_file.txt.t3} -- with columns: \texttt{t3}, \texttt{t4},
    \texttt{t4-t3}
    \item \texttt{output\_file.txt.tx} -- with columns: \texttt{t2-t1},
    \texttt{t4-t3}, \texttt{(t2-t1)+(t4-t3)}
    \end{itemize*}
    The same script can be used on an output from one channel or from an output of
    a sweep over several channels (command \texttt{insitu run}).
    To generate a plot out of the generated files the following scripts can be used:
    \begin{itemize*}
    \item \texttt{./plot\_t2t1.gnuplot output\_file.txt.t1} -- to plot t2-t1;
    an example plot can be seen in Figure~\ref{fig:insitu_t2t1}
    \item \texttt{./plot\_t4t3.gnuplot output\_file.txt.t3} -- to plot t4-t3;
    an example plot can be seen in Figure~\ref{fig:insitu_t4t3}
    \item \texttt{./plot\_t2t1t4t3.gnuplot output\_file.txt.tx} -- to plot
    (t2-t1)+(t4-t3);
    an example plot can be seen in Figure~\ref{fig:insitu_t2t1t4t3}
    \end{itemize*}
    \begin{figure}[!ht]
    \begin{center}
    \includegraphics[width=.7\textwidth]{fig/insitu.t1.t2t1.png}
    \caption{t2-t1 of a sweep over all SFP channels}
    \label{fig:insitu_t2t1}
    \end{center}
    \end{figure}
    \begin{figure}[!ht]
    \begin{center}
    \includegraphics[width=.7\textwidth]{fig/insitu.t3.t4t3.png}
    \caption{t4-t3 of a sweep over all SFP channels}
    \label{fig:insitu_t4t3}
    \end{center}
    \end{figure}
    \begin{figure}[!ht]
    \begin{center}
    \includegraphics[width=.7\textwidth]{fig/insitu.tx.t2t1t4t3.png}
    \caption{(t2-t1)+(t4-t3) of a sweep over all SFP channels}
    \label{fig:insitu_t2t1t4t3}
    \end{center}
    \end{figure}
    \FloatBarrier
    \subsection{Known problems}
    \subsubsection{No channel for SFP selected}
    If the message like below appears in the console, make sure that SFPs is
    configured to use a non-zero channel.
    \begin{lstlisting}
    Warning: tx not terminated infinite mcr=0x1001410
    Warning: tx timestamp never became available
    \end{lstlisting}
    Check which channel is selected:
    \begin{lstlisting}
    wrc# sfp info
    [...]
    Current channel number 1
    Current wavelength 1563.85 nm
    \end{lstlisting}
    If needed set the channel to e.g. \texttt{1} by the command:
    \begin{lstlisting}
    sfp tune 1
    \end{lstlisting}
    \subsubsection{WRPC stays in PTP mode}
    It was observed that every few tunes the WRPC goes to the PTP mode.
    For an unknown reason PPSi does not set the link as White Rabbit.
    It can be observed especially when sweeping SFP channels with \texttt{sfp run}
    command. In such case both syntonization and synchronization is done.
    To workaround this problem, please unplug/plug the fiber or restart PPSi by
    executing commands \texttt{ptp stop} followed by \texttt{ptp start}.
    % from scratch the toolchain for RISC-V.
    % Firstly, clone the \texttt{riscv-gnu-toolchain} repo and checkout the tag
    % \texttt{2022.03.09} (or commit \texttt{051b9f7d}). This will allow to build
    % the GCC 11.1.0 for the RISC-V architecture.
    % \begin{lstlisting}
    % git clone https://github.com/riscv/riscv-gnu-toolchain -b 2022.03.09
    % \end{lstlisting}
    % Run the configuration script with parameters to specify the installation
    % directory and the details for the RISC-V architecture.
    % The selected options use soft-float (\texttt{ilp32}) and allow to use
    % compressed instruction set.
    % \begin{lstlisting}
    % ./configure --prefix=<install_dir> --with-arch=rv32i --with-abi=ilp32
    % \end{lstlisting}
    % Start the build of the toolchain.
    % \begin{lstlisting}
    % make
    % \end{lstlisting}
    % The output will be copied to the specified \texttt{<install\_dir>}.
    % --------------------------------------------------------------------------
    \newpage
    ......
    tools/insitu/insitu_process_data.py 0 → 100755
    View file @ f9020875
    #!/usr/bin/python3
    # Author: Adam Wujek, 2022
    import sys
    from fractions import Fraction
    count = 0
    if len(sys.argv) < 2:
    print("Error not enough parameters: " + str(len(sys.argv)))
    print("open file: " + sys.argv[1])
    file_t1 = open(sys.argv[1] + '.t1', 'w')
    file_t3 = open(sys.argv[1] + '.t3', 'w')
    file_tx = open(sys.argv[1] + '.tx', 'w')
    t21f_sum = Fraction(0)
    t21f_cnt = 0
    t43f_sum = Fraction(0)
    t43f_cnt = 0
    with open(sys.argv[1]) as fp:
    while True:
    count += 1
    line = fp.readline()
    if not line:
    break
    fields = line.split()
    if len(fields) == 0:
    continue
    if fields[0] == "t1t2:":
    t1f = Fraction(fields[1])
    t2f = Fraction(fields[2])
    t21f = t2f-t1f
    file_t1.write(fields[1]+" "+fields[2]+" "+str(float(t21f % 1))+str("\n"))
    if fields[0] == "t3t4:":
    t3f = Fraction(fields[1])
    t4f = Fraction(fields[2])
    t43f = t4f-t3f
    file_t3.write(fields[1]+" "+fields[2]+" "+str(float(t43f % 1))+str("\n"))
    try:
    # may fail if t4t3 is the first in the file
    file_tx.write(str(float(t21f % 1))+" "+str(float(t43f % 1))+" "+str(float(t43f+t21f))+str("\n"))
    except NameError:
    pass
    tools/insitu/plot_t2t1.gnuplot 0 → 100755
    View file @ f9020875
    #!/usr/bin/env -S /usr/bin/gnuplot -c
    # Author: Adam Wujek, 2022
    LOGFILE=ARG1
    print "Using log file : ", LOGFILE
    output_scale = 4
    set output LOGFILE.".t2t1.png"
    if (!exists("scale_x")) scale_x=640
    if (!exists("scale_y")) scale_y=480
    set terminal pngcairo size scale_x*output_scale,scale_y*output_scale enhanced font "arial,10" fontscale output_scale linewidth output_scale
    set title "t2-t1"
    set ylabel "s"
    set ytics format "%.11f"
    set xlabel "sample"
    plot LOGFILE u ($3) notitle
    tools/insitu/plot_t2t1t4t3.gnuplot 0 → 100755
    View file @ f9020875
    #!/usr/bin/env -S /usr/bin/gnuplot -c
    # Author: Adam Wujek, 2022
    LOGFILE=ARG1
    print "Using log file : ", LOGFILE
    output_scale = 4
    set output LOGFILE.".t2t1t4t3.png"
    if (!exists("scale_x")) scale_x=640
    if (!exists("scale_y")) scale_y=480
    set terminal pngcairo size scale_x*output_scale,scale_y*output_scale enhanced font "arial,10" fontscale output_scale linewidth output_scale
    set title "(t2-t1)+(t4-t3)"
    set ylabel "ns"
    set ytics format "%.3f"
    set xlabel "sample"
    plot LOGFILE u ($3*1000000000) notitle
    tools/insitu/plot_t4t3.gnuplot 0 → 100755
    View file @ f9020875
    #!/usr/bin/env -S /usr/bin/gnuplot -c
    # Author: Adam Wujek, 2022
    LOGFILE=ARG1
    print "Using log file : ", LOGFILE
    output_scale = 4
    set output LOGFILE.".t4t3.png"
    if (!exists("scale_x")) scale_x=640
    if (!exists("scale_y")) scale_y=480
    set terminal pngcairo size scale_x*output_scale,scale_y*output_scale enhanced font "arial,10" fontscale output_scale linewidth output_scale
    set title "t4-t3"
    set ylabel "s"
    set ytics format "%.11f"
    set xlabel "sample"
    plot LOGFILE u ($3) notitle
    Markdown is supported
    0% or
    You are about to add 0 people to the discussion. Proceed with caution.
    Finish editing this message first!
    Please register or to comment