ppk2.html

A power profiler for the Nordic Power Profiler Kit II (PPK2) in a single web page. It talks to the device directly over the Web Serial API, so there's nothing to install: no drivers, no desktop app, no backend, no dependencies.

Not affiliated with or endorsed by Nordic Semiconductor.

Use it

Open https://pilate.github.io/ppk2.html/ in a desktop browser (try it with a simulated PPK2). Connecting a PPK2 needs Web Serial: Chrome and Edge have it, and recent Firefox versions expose it too. Without it you can still open, view, save and export recordings, and use the simulated device.

To get the app as a single file, download it from that page with your browser's Save page as, or build it:

python3 build.py          # writes dist/ppk2.html

dist/ppk2.html is the whole app: styles and code are inlined, so you can double-click it, email it or put it on any static host. It works straight from disk (file://) as well as over https://. The only outside request is for the Barlow web fonts; offline it falls back to system fonts.

No PPK2 at hand? Click Use simulated device, or add ?demo to the URL to connect the simulator and start sampling straight away.

Close nRF Connect Power Profiler (or any serial terminal) first. Only one program can open the PPK2 at a time.

Develop

The source is plain HTML, CSS and ES modules: ppk2.html loads css/ and js/ directly. Browsers won't load modules from file://, so serve the folder while working on it:

python3 -m http.server 8000
# then open http://localhost:8000/ppk2.html

On WSL, run the server inside WSL and open the page in Chrome or Edge on Windows; the PPK2 stays attached to Windows, where the browser can see it. Run python3 build.py again to refresh dist/ppk2.html after changes.

Every push to main runs the tests, builds dist/ppk2.html and publishes it to GitHub Pages (.github/workflows/pages.yml).

Features

Modes	Source meter (PPK2 supplies 0.8–5 V) and ammeter
Power	Set supply voltage, switch power output on and off
Sampling	100 kHz native, or averaged down to 50k/20k/10k/1k/100/10/1 Hz for long recordings; optional stop-after duration
Chart	Live view, scroll to zoom, drag to pan, min/max envelope at any zoom down to individual samples, linear or log current axis, overview strip of the whole recording
Lanes	A band below the chart with a small current lane and D0–D7 logic lanes (each can be shown or hidden); click a lane to show that signal in the big chart, as a current trace or a large logic waveform
Measure	Average current of the whole run; average, min, max, charge and energy for the visible window and for a selected range (with its duration); a status indicator for recording, waiting for a trigger, stopped and so on
Trigger	Rising or falling edge at a current level, capture length, pre-trigger percentage, single or continuous
Files	Save and open recordings as .ppk2, the same format as nRF Connect, so files open in either app; export everything or the selection as CSV with the same columns as nRF Connect; save the chart as PNG
Advanced	Spike-filter tuning, per-range gain adjustment (stored on the PPK2), calibration data viewer, memory limit
Robustness	Detects lost samples from the PPK2's sample counter and marks them as gaps; realigns the stream automatically after USB buffer overruns

Keyboard (with the chart focused): ←/→ pan, +/− zoom, F show all, L follow live, Esc clear selection. Space starts and stops sampling.

How it works

ppk2.html, css/app.css       UI (source page)
build.py                     bundles everything into dist/ppk2.html
js/app.js                    wires controls, device, recorder and chart together
js/settings.js               settings defaults, saved in the browser (only what differs from the defaults)
js/ui.js                     small page widgets: number boxes, steppers, hints, segmented controls
js/transport.js              Web Serial port, plus a simulated PPK2 (same byte protocol)
js/ppk2.js                   device commands, metadata/calibration readout, sample stream
js/protocol.js               command bytes, metadata parser, sample decoder and calibration
js/recorder.js               downsampling, stop-after limit, software trigger
js/store.js                  chunked sample storage with a min/max/sum pyramid
js/chart.js                  canvas chart and overview strip
js/ppk2file.js               the .ppk2 recording format (nRF Connect compatible)
js/fileio.js                 save dialog / download, .ppk2 save and open, CSV, PNG
js/zip.js                    ZIP reading and writing with the browser's deflate
js/format.js                 SI-prefixed number formatting and axis ticks
tests/                       unit, end-to-end and file-format tests (Node 20+)

Protocol. The PPK2 is a USB CDC device (VID 0x1915, PID 0xC00A). Commands are a few bytes each: 0x19 returns the calibration block as text ending in END, 0x06/0x07 start and stop streaming, 0x11 sets the mode, 0x0D sets the supply in mV, 0x0C switches power output, 0x25 sets a range gain. While streaming, every sample is a little-endian 32-bit word: 14-bit ADC value, 3-bit range, 6-bit counter and 8 digital bits. Converting the ADC value to current uses the per-range calibration (R, GS, GI, O, S, I, UG) the device reports, plus the same spike filter nRF Connect applies when the range switches.

Storage. Samples go into 1 Mi-sample chunks. Each chunk keeps min, max, sum and digital OR/AND for buckets of 16, 256, 4 096 and 65 536 samples, so drawing a pixel column or computing statistics over any range touches roughly a hundred values, however long the recording. Memory use is about 6.4 bytes per sample (512 MB holds about 14 minutes at 100 kHz); when the limit is reached the oldest data is dropped.

Recording files use nRF Connect's .ppk2 format: a ZIP archive (deflate, ZIP64 past 4 GiB) with metadata.json ({ metadata: { samplesPerSecond, startSystemTime }, formatVersion: 2 }, plus a ppk2html object with mode, supply voltage, source device and time offset that nRF Connect ignores), minimap.raw (the JSON overview nRF Connect needs to open a file, built with a port of its folding algorithm) and session.raw (6 bytes per sample: little-endian float32 current in µA, NaN for lost samples, then a big-endian uint16 with 2 bits per digital channel: 01 low, 10 high, 11 toggled within the sample). The ZIP code (js/zip.js) uses the browser's built-in deflate, so saving and opening work in Firefox too, where files save as downloads.

From the browser console, ppk2.chart, ppk2.recorder, ppk2.device, ppk2.session and ppk2.settings give access to the live objects.

Tests

npm test        # or: node --test tests/*.test.js

The tests cover metadata parsing, command encoding, decoding across ranges and split reads, lost-sample detection, stream realignment, storage aggregates against brute force (including eviction), the chart's reusable summary bins, downsampling, the trigger, saving settings, .ppk2 save/load and CSV export, and an end-to-end run against the simulated device.

Not yet supported

• Opening the older .ppk files from nRF Connect versions before .ppk2
• Streaming very long recordings straight to disk (the recording lives in memory, up to the limit you set)
• Firmware update of the PPK2 (use nRF Connect)