DM40GUI

DM40GUI is a Windows desktop app for DM40-series multimeters over Bluetooth Low Energy (BLE).

• Windows only (if someone wants to maintain a non-Bleak Linux BLE stack let me know)
• Tkinter UI
• Pure Python runtime from source (no third-party runtime dependencies)

BRANDING MATERIAL NEEDED (ICON&BANNER), WILL PAY!!!

Go to the Release page to download the latest build

Features

Live Readout and Waveform

• Scrolling waveform graph with live value display
• Pause/resume updates
• CSV save and record for waveform data
• Min/Max/Avg stats strip aligned with current display scaling
• Click to pin a sample, drag to select a range — shows min/max/delta and timestamp span

DMM Controls

• Hold, auto-range, relative, and mode/range switching
• Status indicators (charge, screen lock and hold) are also displayed
• Almost 100% feature compatibility with atk-xtool

Raw Packet Inspector

• Hex packet log with inline CRC pass/fail tags
• Find tool (Ctrl+F / F3 / Shift+F3)

Themes

• 17 built-in themes, persisted across sessions
• Theme browser with live preview

Requirements

Minimum: Windows 10 version 1703 (Creators Update, build 15063). The BLE GATT APIs used (IBluetoothLEDevice3, IGattDeviceService3) were introduced in that release. Connection parameter tuning (IBluetoothLEDevice6) is available on Windows 11+ and silently skipped on older builds.

Runtime (source):

• Windows 10 1703+
• Python 3.13+ with Tkinter

Release build:

• Python 3.13+
• Nuitka
• MSVC Build Tools (Nuitka --msvc=latest target)

Notes: Older python versions untested.

Keybinds

Global app shortcuts:

Keybind	Action
P	Pause/resume waveform updates
R	Start/stop waveform CSV recording
Ctrl+S	Save current waveform buffer to CSV
Ctrl+C	Copy current reading text

Raw packet viewer shortcuts:

Keybind	Action
Ctrl+F	Open find popup in raw packet panel
Enter	Next find result
Shift+Enter	Previous find result
F3	Next find result
Shift+F3	Previous find result
Esc	Close find popup / clear active focus state

Waveform mouse actions:

Action	Behavior
Left click on trace	Pin tooltip at a sample
Left-click drag	Select range and show min/max/delta
Right click	Clear pinned point / clear selection

Project Layout

Path	Description
main.py	App entry point
dm40/app.py	Tk app and UI event loop integration
dm40/ble_worker.py	BLE transport worker thread
dm40/parsing.py	Packet decode to UI model
dm40/protocol_constants.py	UUIDs, command bytes, mode/range maps
GUI/	Widgets, controls, theme UI
build_release.cmd	One-file Nuitka build script

Protocol Notes

Reverse-engineered from BLE HCI packets with Wireshark.

BLE Endpoints

Direction	UUID
Notify (DMM -> PC)	0000fff1-0000-1000-8000-00805f9b34fb
Write (PC -> DMM)	0000fff3-0000-1000-8000-00805f9b34fb

Defined in dm40/protocol_constants.py.

Command Frames

All commands are 6 bytes:

AF 05 03 <cmd> <arg> <checksum>

Checksum formula:

(-sum(first_5_bytes)) & 0xFF

Built by _build_command_packet in dm40/app.py.

Known commands:

CMD_ID          af 05 03 08 00 41
CMD_READ        af 05 03 09 00 40
CMD_HOLD_ON     af 05 03 04 01 01
CMD_HOLD_OFF    af 05 03 04 01 00
CMD_AUTO_ON     af 05 03 03 01 01
CMD_AUTO_OFF    af 05 03 03 01 00
CMD_RELATIVE    af 05 03 05 01 01

Notifications

Two packet families:

• Model ID: prefix DF 05 03 08 14.
• Measurement: prefix DF 05 03 09, decoded by parse_measurement_for_ui.

Measurement Decode

Minimum packet length: 16 bytes.

Byte(s)	Field
data[5]	Mode/range flag (FLAG_INFO)
data[6]	Status byte
data[14:16]	Primary counts (m1, little-endian)
data[12:14]	Secondary counts (m2, little-endian)
data[10:12]	Tertiary counts (m3, little-endian)
data[-8]	Scale/sign slot 1
data[-9]	Scale/sign slot 2
data[-10]	Scale/sign slot 3

CRC check:

(sum(all_bytes) & 0xFF) == 0

Status Byte

data[6] bitfield:

Bits	Meaning
& 0x07	Battery level (0-5 bars)
& 0x08	Charging
& 0x40	Screen lock
& 0x80	Hold

Notes:

Stability

The project is still in an early state, I cannot guarantee measurement correctness for multiple reasons:

1. The DMM doesn't expose all measurement scale/range byte variations unless I am measuring in that specific scale, without decade boxes I'm unable to verify all scale/ranges due to this, if the App crashes with a KeyError the scale is probably not implemented yet, please report this.

2. I do NOT have a lot of time to work on this.

Disclaimer

This project is not affiliated with, endorsed by, or associated with Alientek or any of its subsidiaries.

Use of AI

Claude Opus 4.6 used to write (some of) the Readme files

Run from Source

py -3.13 main.py

No additional runtime package install is required for source execution.

Build for Release

Install build dependency:

py -3.13 -m pip install --upgrade nuitka

Run build script:

build_release.cmd

The script is CI-friendly:

• deterministic compiler/linker env setup
• non-zero exit on failure
• configurable via DM40_* environment variables

Build environment variables:

Variable	Purpose
DM40_PYTHON	Python launcher/command (default: py -3.13)
DM40_OUT_DIR	Build output directory
DM40_CCFLAGS	Additional compiler flags
DM40_LINKFLAGS	Additional linker flags
DM40_NUITKA_FLAGS	Additional Nuitka flags
DM40_MODE_FLAGS	Build mode flags (default: --deployment)
DM40_CONSOLE_MODE	Nuitka console mode (disable, attach, force)
DM40_MSVC	Nuitka MSVC selector (default: latest)
DM40_JOBS	Parallel compile jobs
DM40_EMIT_MODULE_REPORTS	Emit modules.txt and compilation XML report (1 local default, 0 default when CI is set)

Minimal CI example (Windows CMD shell):

set DM40_PYTHON=py -3.13
set DM40_OUT_DIR=build\ci\nuitka
call build_release.cmd

License

Licensed under LICENSE.