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Make the data from USB power meters usable in the Firefox Profiler.

Quick start

The following instructions will start a server on localhost:2121.

git clone https://github.com/fqueze/usb-power-profiling.git
cd usb-power-profiling
npm i
node usb-power-profiling.js

Then open the Firefox Profiler UI to load the data from the meter. You can also load http://localhost:2121/ in your browser to see a live power profile (updated every 5 seconds).

External power profiling in the Firefox Profiler

In Firefox 121 or later:

  • in about:config, set the devtools.performance.recording.power.external-url preference to http://localhost:2121/power.
  • use the 'power' preset (or any configuration that uses the 'power' feature) when starting the profiler.
  • When capturing the profile, the Firefox Profiler will automatically fetch additional power tracks and add them to the profile.

Seeing a profile containing only the data from the USB power meter

Load http://localhost:2121/profile in the Firefox Profiler.

HTTP API

  • GET /profile will return a profile containing all the data since the script has started. You can view it by loading it in the Firefox Profiler.
  • GET /power?start=<start timestamp in ms>&end=<end timestamp in ms> returns only a power track to be added into a profile from the Gecko Profiler. The start timestamp should be profile.meta.startTime + profile.meta.profilingStartTime from the profile and the end timestamp should be profile.meta.startTime + profile.meta.profilingEndTime.
  • GET /rawdata?last=<timestamp> returns all the stored data in JSON format if the last timestamp is omitted, or all data more recent than the provided last timestamp if it is provided. This API is used by the live profiling web UI.

Supported devices

Power meters known to work

The example profiles are taken using a USB light, first keeping the light off for a while to record noise from the power meter, then turning the light on at different levels of brightness for about 5s, and finally turning the light off again.

Brand Model Example profile Min interval between samples Notes
ChargerLab Power-Z FL001 Super https://share.firefox.dev/4714rQQ 32ms
ChargerLab Power-Z KM001Pro https://share.firefox.dev/4ag8xqN 2ms
ChargerLab Power-Z KT002 https://share.firefox.dev/3RkPsvf 1ms Samples contain timestamps in µs, and sampling is driven by the power meter, making the sampling rate very consistent (no degradation of the data when the USB bus is busy)
ChargerLab Power-Z KM003C https://share.firefox.dev/3Rg6z15 1ms Sampling driven by the computer, causing overhead on the computer and relying on the USB communication being smooth.
Shizuku YK-Lab YK001 See Power-Z KT002. Alternative names: AVHzY CT-3, Power-Z KT002, or ATORCH UT18.
Shizuku YK-Lab YK003C See AVHzY C3.
AVHzY CT-3 See Power-Z KT002.
AVHzY C3 https://share.firefox.dev/41BVhcf 1ms Samples contain timestamps in µs, and sampling is driven by the power meter, making the sampling rate very consistent (no degradation of the data when the USB bus is busy)
AVHzY TC66C (RD) See RuiDeng TC66C
FNIRSI C1 https://share.firefox.dev/4asQhLh 10ms Significant power use changes are smoothed over 500ms.
FNIRSI FNB48S https://share.firefox.dev/3RjtVTl 10ms Significant power use changes are smoothed over 120ms.
RuiDeng TC66C https://share.firefox.dev/3v4AvFV 80ms Sampling rate depends on how much data is displayed on the power meter's screen. With the full display, 100ms is the minimum interval between samples. With only the main 3 values displayed, 90ms is in the minimum between samples, with a static screen (eg. settings) the minimum interval is 80ms. Significant power changes take up to 500ms to stabilize (with a few samples showing only a part of the change).
WITRN C5 https://share.firefox.dev/41nqAaQ 10ms Samples contain timestamps in ms.
ATORCH ACD15P https://share.firefox.dev/3SIWpGS 1s Very low sampling rate.
YZXStudio 1280E https://share.firefox.dev/3Wr9HeW 250ms Low sampling rate. Significant power changes take up to 500ms (2 samples) to stabilize. Seems to have a low level of noise, making it possible to see a difference between low power values ( <10mW) and 0.

Power meters likely to work

Compatibility with these devices has not been verified, but they are likely to either "just work", or work with a trivial adjustment to the code (eg. tweak a USB product id).

Brand Model Notes
ChargerLab Power-Z KM002C Same protocol as the KM003C.
FNIRSI FNB48 Expected to use the same protocol as the FNIRSI C1.
FNIRSI FNB48P Expected to be the same as the FNIRSI FNB48S in a different package.
FNIRSI FNB58 Expected to use the same protocol as the FNIRSI FNB48S.
RuiDeng TC66 Expected to use the same protocol as the TC66C.
WITRN A2 Expected to use the same protocol as the C5.
WITRN A2L Expected to use the same protocol as the C5.
WITRN A2C Expected to use the same protocol as the C5.
WITRN U3 Expected to use the same protocol as the C5.
WITRN U3L Expected to use the same protocol as the C5.
WITRN C4 / C4L Expected to be the same as the C5 with lower data precision.
ATORCH C13P Expected to be the same as the ACD15P.

Installation on Windows

Windows requires the WinUSB driver to be installed and bound in order to work.

The instructions below are for the AVHzY CT-3. The USB ID at least will be different for other devices.

  • Install Zadig driver installer from https://zadig.akeo.ie/
  • Plug in the USB power meter and run the Zadig application
  • Disable the Options -> Ignore Hubs or Composite Parents option in the menu
  • Select the USB device for the meter (for CT-3 it is USB ID 0483 FFFE)
  • Click Replace to install the default WinUSB driver

With those steps, it should now be possible to run the node application above and sample power.