atorch-ble

A standalone Python parser for the Atorch BLE protocol used by USB/AC/DC power meters such as the J7-C and UC96. The package provides byte-level notification-frame reassembly, packet decoding, and typed dataclasses for measurements, with no Home Assistant dependency so it can be used from any async or sync Python program. This package is consumed by the atorch_ble Home Assistant integration, which declares it as a manifest.json requirement following the Bluetooth-Devices org pattern that keeps raw byte parsing out of HA Core.

Status: v0.1 — initial release, J7-C / packet type 0x03 only.

Installation

pip install atorch-ble

Requires Python 3.12 or newer.

Usage

from atorch_ble import AtorchBleParser, UnsupportedPacketType, UsbMeterReading

# A canonical 36-byte J7-C USB-meter frame (synthetic, derived from the
# documented byte layout). In real use you'd feed the bytes you receive
# from a bleak notification callback.
frame = bytes.fromhex(
    "ff55010300020000007b0001c800000315010f0110001b01020304"
    "000000000000ec0000"
)

parser = AtorchBleParser()
try:
    readings: list[UsbMeterReading] = parser.feed(frame)
except UnsupportedPacketType as exc:
    # Raised for non-J7-C packet types (e.g. DL24/UD18 DC meters).
    print(f"unsupported packet type: 0x{exc.packet_type:02x}")
    readings = []

for r in readings:
    print(f"voltage:     {r.voltage_v} V")
    print(f"current:     {r.current_a} A")
    print(f"capacity:    {r.capacity_mah} mAh")
    print(f"energy:      {r.energy_wh} Wh")
    print(f"D+ / D-:     {r.voltage_dplus_v} V / {r.voltage_dminus_v} V")
    print(f"temperature: {r.temperature_c} C")
    print(f"duration:    {r.duration_s} s")

AtorchBleParser.feed() accepts raw bytes from a single BLE notification callback (zero, partial, one, or multiple frames) and returns the list of fully decoded UsbMeterReading instances. Recoverable decode failures (bad length, magic, direction byte, or checksum mismatch) are swallowed and recorded on parser.error_count / parser.last_error; UnsupportedPacketType is re-raised so callers can surface it to the user.

Supported devices

Development

git clone https://github.com/dallanwagz/atorch-ble
cd atorch-ble
pip install -e ".[dev]"
pytest

Quality gates: ruff for lint and formatting, mypy --strict for typing, and pytest with a 95% coverage floor.

License

MIT — see LICENSE.