WITRN UI BOKEH

The code on this repository builds upon the existing Python driver-functionality of witrn-ui by didim99, by adding real-time plotting (and logging) functionality using Bokeh. The result allows the user to control a WITRN USB-meter to be controlled using a web-browser.

Currently the code has only been tested using a Witrn C4.

1 - Installation

1.1 - Install required packages

pip install -r requirements.txt

NOTE: The requirements.txt file is generated by running pipreqs (pip install pipreqs) in the project directory. ~= means compatible version.

1.2 - Configure platform-dependent functionality

1.2.1 - Linux

Copy the udev-rules-file to the correct location.

sudo cp udev/90-usbmeter.rules /etc/udev/rules.d/90-usbmeter.rules

Restart the udev management tool.

sudo udevadm control --reload-rules
sudo udevadm trigger

1.2.2 - Windows

Use Zadig to replace Windows's default HID-driver to libusbK.

1. Run zadig-2.8.exe
2. Click on Options > List All Devices
3. Select the WITRN.C4 device (in case the Witrn C4 is used)
4. Select libusbK (v3.0.7.0) above the Replace Driver button
5. Click on Replace Driver
6. Confirm the driver replacement operation, wait for the tool to finish

2 - Running

Running witrn-ui-bokeh.py as-is with Python won't do anything. It is supposed to be launched using Bokeh server (bokeh serve), which creates (and opens, on http://localhost:5006/witrn-ui-bokeh) an interactive web application that connects front-end UI events to running Python code. The correct usage is shown below.

bokeh serve --show witrn-ui-bokeh.py

Once the web-interface opens, use the following steps.

1. Select a Device using the dropdown (C4 selected by default).
   • Depending on the way the current will flow/flows through the USB-meter, disable (default enabled) the Invert Current Sign logic using the corresponding toggle-switch.
2. Click on Open Connection
   • Change the Plot Period [ms] to a value greater than 0 if the measurement-throughput is too/unnecessary high (the tool defaults to (try to) plot all incoming measurements, a non-zero value only plots incoming measurements at the defined period)
   • Click on Clear Plot to clear all of the already plotted measurements (the tool only keeps 6000 (configurable, using MAX_X_POINTS in witrn-ui-bokeh.py) data-points on the X-axis (per data-line) before discarding old data, in an attempt to maintain a somewhat responsive real-time application)
   • Click on an item in the Legend to enable or disable the display of certain lines on the plot
3. Use the tooltips on the side (activated when hovering over the plot) to zoom in or out on the measurements, ...
4. Change the plot- and file- Title and Log Period [ms] using the corresponding fields (if necessary), click on Start Logging to start saving values to a .csv-file.
   • The generated file has the following syntax (DateTime corresponds to the time at which the button has been pressed): YYYY-MM-DD_HH-MM-SS_<Title>.csv

Usage sample:

3 - TODO

• Add functionality to re-plot stored CSV-data
• Add functionality to "download" offline recordings from the USB-meter
• Implement U2P functionality (see this and this)
• Implement TC66 functionality (see this)