121GW for Linux

Native GTK4 / libadwaita companion app for the EEVblog 121GW multimeter, talking to the meter over Bluetooth LE through BlueZ.

It is a port of the official EEVblog app-121gw and the evotronix iOS / Windows / Android / Chrome ports (iOS v1.4.22 feature set): same packet decoder, key codes, logging behaviour and Live / Sessions / Connect layout.

Pure Python + PyGObject. BLE goes straight to BlueZ over D-Bus, so there is nothing to pip install.

Features

Live

• LCD replica: BT, AUTO, 1kHz, 1ms, LowZ, BAT, APO, DC / AC / DC+AC, DIODE, CONT, REL, HOLD, MIN / MAX / AVG, MEM, dBm, TEST annunciators, sign, overload (OL)
• 26-segment analog bargraph with 0–5 / 0–10 scale and range marker (from the original EEVblog app)
• Secondary display: internal temperature, frequency (AC V), dBm, burden voltage, beeper threshold
• SETUP pages decoded: battery, time, date, year, beeper, auto power-off, LCD contrast, logging interval, meter ID, calibration
• Header: link RSSI (dBm), meter battery voltage, meter clock
• Warnings: communication lost (5 s watchdog), battery low (≤ 4.5 V) and near power-off (≤ 4.2 V), also as desktop notifications when the window is in the background
• Remote keys HOLD / MODE / REL▲ / RANGE / MIN-MAX / MEM / PEAK▼ / SETUP with short and long press (MODE long ≈ backlight); REL / PEAK act as ▲ / ▼ in the SETUP menu
• Trend chart: Y axis follows the meter mode/range (or “Auto Y”), mouse-wheel zoom, drag to pan, double-click to reset, hover readout, dashed internal-temperature trace with show/hide toggle. It shows a rolling preview before logging starts and the full 25,000-sample window while logging.

Logging & sessions

• Start / Stop & Save, with a session name prompt
• Logging pauses when the measurement function changes (range changes stay in the same log and are normalized for the graph). You are asked whether to save, then logging resumes.
• Session list with statistics (samples, duration, min, max, average, peak-peak, std-dev, rate)
• Notes (auto-saved), rename, delete, delete all
• Export full-resolution CSV and the graph as PNG

Connect

• Scan, device list with RSSI, connect, disconnect
• Auto-reconnect to the last meter (scans in the background and connects as soon as it advertises)
• “Show all BLE devices” for meters that advertise without their name
• Detects a powered-off or rfkill-blocked adapter and offers “Turn On Bluetooth”
• Continuity feedback: beep with ON/OFF ohm hysteresis (defaults ON < 25 Ω, OFF > 400 Ω), diode-conduction beep, ON threshold synced from the meter’s beeper setting, test beep

Linux extras

• --demo simulated meter (real frames through the real parser, reacts to the keys) to try the app without hardware
• Keyboard shortcuts: H HOLD, M MODE, R REL, G RANGE, X MIN/MAX, E MEM, P PEAK, S SETUP, Shift+key = long press, ↑/↓ in SETUP, Ctrl+L log, Ctrl+1/2/3 tabs

Vibration feedback from the mobile apps has no PC equivalent and is omitted. The original Xamarin app’s multi-meter tabs aren’t carried over either; like all the evotronix ports, this app connects to one meter.

Install

One command: it checks/installs the dependencies (Arch, Debian/Ubuntu, Fedora, openSUSE), downloads the app and adds 121GW Multimeter to your app launcher. No root needed except for missing system packages.

curl -fsSL https://raw.githubusercontent.com/bigtimer-dev/121gw-linux/main/install.sh | bash

Or from a clone:

git clone https://github.com/bigtimer-dev/121gw-linux.git
cd 121gw-linux
./install.sh

Then open 121GW Multimeter from your launcher, or run 121gw (121gw --demo without a meter). Run the same command again to update. Uninstall with ./install.sh --uninstall (or curl … | bash -s -- --uninstall). Installer options: --yes (install missing packages without asking), --no-deps (skip the dependency check).

Requirements

• Python ≥ 3.10, PyGObject, pycairo, GTK ≥ 4.12, libadwaita ≥ 1.6 (Arch, Fedora 41+, Ubuntu 25.04+, Debian 13+, openSUSE Tumbleweed)
• BlueZ (bluetooth.service running) and a Bluetooth LE adapter
• For the continuity beep: pw-play, paplay or aplay

Run without installing

python3 -m gw121          # real meter
python3 -m gw121 --demo   # simulated meter

Connecting the meter

1. Make sure Bluetooth is on: rfkill unblock bluetooth && bluetoothctl power on (or use Turn On Bluetooth on the Connect tab).
2. On the 121GW hold 1ms PEAK until the BT icon appears.
3. The app connects automatically (auto-reconnect), or press Scan on the Connect tab and pick the meter. Pairing is not needed.

Files

What	Where
Settings	~/.config/121gw/settings.json
Sessions	~/.local/share/121gw/sessions.json

Protocol notes

• BLE service 0bd51666-e7cb-469b-8e4d-2742f1ba77cc (Bluegiga Cable Replacement); data characteristic e7add780-b042-4876-aae1-112855353cc1, frames arrive as indications
• 19-byte frames: 0xF2, …, XOR checksum of bytes 0–17 in byte 18 (gw121/packet.py)
• Keys: F4 k c k c, k = 0x30 short / 0x38 long, c = 0x31…0x38 (RANGE, HOLD, REL, PEAK, MODE, MIN/MAX, MEM, SETUP)

Development

python3 -m unittest discover -s tests

Layout: packet.py decoder · bluez.py BLE transport · demo.py simulator · link.py shared live state · sessions.py logging/CSV · continuity.py beeper · chart.py trend chart · lcd.py LCD widget · window.py UI · app.py entry point.

License

MIT, like the upstream projects. See LICENSE.