https://github.com/nbuchwitz/usb-meter

Python library for USB-C power meters. Initial support: ChargerLAB POWER-Z KM003C over its HID transport.
https://github.com/nbuchwitz/usb-meter

km003c meter power powerz usb

Last synced: 24 days ago
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Python library for USB-C power meters. Initial support: ChargerLAB POWER-Z KM003C over its HID transport.

• Host: GitHub
• URL: https://github.com/nbuchwitz/usb-meter
• Owner: nbuchwitz
• License: lgpl-2.1
• Created: 2026-05-29T09:35:38.000Z (26 days ago)
• Default Branch: main
• Last Pushed: 2026-05-29T09:47:30.000Z (26 days ago)
• Last Synced: 2026-05-29T11:21:46.466Z (26 days ago)
• Topics: km003c, meter, power, powerz, usb
• Language: Python
• Homepage:
• Size: 22.5 KB
• Stars: 0
• Watchers: 0
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          


# usb-meter

[![License: LGPL v2.1+](https://img.shields.io/badge/License-LGPL_v2.1+-blue.svg)](https://www.gnu.org/licenses/lgpl-2.1)

[![Python 3.10+](https://img.shields.io/badge/python-3.10+-blue.svg)](https://www.python.org/downloads/)

Python library for USB-C power meters. Initial support: ChargerLAB

POWER-Z **KM003C** over its HID transport.

The library talks directly to `/dev/hidraw*`, so it does not fight with

the upstream Linux `powerz` kernel driver (which binds to the device's

vendor-bulk interface and exposes a small subset of values via hwmon).

It also has no third-party dependencies.

## Features

- Find a connected meter by USB vendor/product id.

- Read ADC samples (VBUS, IBUS, VCC1/2, VDP/M, VDD, temperature).

- Compact wire-protocol primitives (message + extension header, opcode

  and attribute enums) shared with the KM002C.

- `usb-meter` CLI for one-shot and streaming reads.

## Installation

Directly from GitHub:

```bash

pip install git+https://github.com/nbuchwitz/usb-meter.git

```

Or from a local checkout:

```bash

pip install .

```

Install the udev rule so non-root users in the `plugdev` group can

access the device:

```bash

sudo install -m 644 etc/udev/rules.d/60-chargerlab-km003c.rules /etc/udev/rules.d/

sudo udevadm control --reload && sudo udevadm trigger

```

## Usage

```python

from usb_meter import KM003C

with KM003C.open() as meter:

    sample = meter.read_adc()

    print(f"{sample.vbus_v:.3f} V, {sample.ibus_a:.3f} A, {sample.temperature_c:.1f} C")

```

Or from the shell:

```bash

usb-meter -n 10 -i 0.2     # 10 samples, 200 ms apart

usb-meter -n 0             # stream forever

```

## Status

Alpha. Only ADC reading is implemented today. The vendor protocol

documents more attributes (`PD_PACKET`, `ADC_QUEUE_10K`, `SETTINGS`,

etc.) that map to the same request/response shape and will land here

incrementally.