labelbee

A network label printer: an ESP32-S3 drives a DYMO LabelManager PnP over USB and serves a label designer in the browser. Design a label on your phone or computer, press Print, done. No driver, no app, no cloud.

Features

• Label designer in the browser: text (18 embedded fonts), QR codes, barcodes (Code 128, Code 39, EAN-13), images (dithered to 1 bit), frames and over 7,000 Material Design Icons. Drag, resize, align, undo, and a preview in the colours of the tape.
• Exact preview: the label is drawn at the printer's 180 dpi, dot for dot, and the browser sends those dots. What you see is what is printed.
• Files on the device: labels are saved on the ESP32 (LittleFS), with previews and dates, and can be opened from any browser in the network.
• Settings page: printer status and battery, WiFi with network scan (DHCP or a fixed address), roaming between access points (802.11k/v), its own access point, time (NTP or the browser's clock), device name, firmware update over WiFi, live log, factory reset.
• Always reachable: labelbee always opens its own WiFi (labelbee) next to the home network, so it can be set up and used without one.
• German and English interface: follows the browser, with a switch that remembers your choice.
• Case: a 3D printed case (OpenSCAD) glued to the side of the printer, with a two colour logo on the lid.

The web interface is plain HTML, CSS and JavaScript without a build step; codes and images are rendered in the browser, the firmware only stores files and talks to the printer.

Hardware

Part	Notes	Used here
DYMO LabelManager PnP	the printer; D1 tape 6, 9 or 12 mm (12 mm and 6 mm tested, 9 mm not yet)
ESP32-S3 DevKitC-1 (N16R8 clone)	16 MB flash, 8 MB PSRAM; its native USB pins drive the printer	amazon.de
USB-A socket breakout	to the printer, wired to GPIO19 (D−) and GPIO20 (D+)	amazon.de
USB-B socket breakout	5 V in from a USB power supply (5 V / 2 A)	amazon.de
3 V relay module (SRD-03VDC-SL-C)	switches the printer's 5 V, controlled by GPIO4	amazon.de
100 µF and 100 nF capacitors	on the printer's 5 V

The links are the parts this one was built from; any equivalent part works (the case is measured for these, see case/).

Wiring, pin positions and checks before the first power-on: docs/wiring.md. The case and how to print it: case/.

Inside the case	On the printer	Power in (top), printer (bottom)

In the photo of the open case the relay is at the top, the ESP32-S3 in the middle with its antenna end free, and both USB breakouts at the bottom, which is the case's back edge: USB-B for the power supply, USB-A with a short cable to the printer. The D+ and D− wires to the USB-A socket are twisted.

Building and flashing

The firmware uses ESP-IDF 6.0.1 through PlatformIO (platform = espressif32@7.0.1):

pio run                      # build
pio run -t upload            # flash over the USB-C socket with the USB serial chip
pio device monitor           # serial console, 115200 baud

Warning

Disconnect the power supply while the board is connected to a computer: it is not known whether the board separates the two 5 V sources.

Later updates go over WiFi, from the settings page or with

curl --data-binary @.pio/build/labelbee/firmware.bin http://labelbee.local/api/ota

A new firmware runs on probation: it counts as good once its web server is up (first answered request, or 30 s after it started). If it crashes or restarts before that, the bootloader starts the previous version again, and the settings page says so. WiFi is no criterion, since labelbee also runs with only its own access point.

First start

1. Power labelbee. It switches the printer on and opens the WiFi labelbee (password labelbee).
2. Join it and open http://192.168.4.1/settings. Under Network, choose your WiFi and save; labelbee restarts and joins it.
3. From then on open http://labelbee.local/ in your home network (or its IP address, shown on the settings page). The own WiFi stays available as a way in.

The serial console has a wifi <ssid> <password> command as an alternative to step 2.

labelbee has no authentication: anyone in the network (and in its own WiFi) can print and change settings. Give the access point a password and keep it in a network you trust.

HTTP API

Request	Purpose
GET /api/status	tapes, resolution, printer state, cassette, battery
POST /api/print?tape=12mm&width=W[&copies=N]	print; body: columns left to right, height/8 bytes each, top dot = MSB
POST /api/test-print?tape=12mm[&offset=N]	a test pattern; offset tries another head dot for the image to start at (to centre a tape), ruler=1 prints a ruler over the whole head
POST /api/power?on=0|1	switch the printer
GET /api/templates, PUT|DELETE /api/templates/<name>	saved labels (designer JSON)
GET|POST /api/settings	settings (POST restarts)
GET /api/info, GET /api/log?since=N	system information, log
GET /api/scan	WiFi networks in reach
POST /api/time?ms=<unix ms>	set the clock from the browser when there is no NTP
POST /api/ota, POST /api/restart, POST /api/factory-reset[?files=1]	maintenance

Everything else is a file of the web interface. Messages from the firmware are in English; the interface translates them.

Repository

Path	Contents
src/	firmware: USB host and printer (printer.cpp), print data (label.cpp), WiFi (net.cpp), settings (config.cpp), HTTP server (web.cpp), files (store.cpp), log (logbuf.cpp)
www/	web interface: designer (index.html, app.js), settings (settings.html, settings.js), translations (i18n.js), fonts and vendored libraries
tools/	build hooks (pack_www.py embeds www/, version_stamp.py) and generators for the icon data
docs/	wiring, the printer's USB protocol (docs/protocol.md), images
case/	the case (OpenSCAD model and STL files)
logo/	the logo

Credits

The print protocol builds on dymoprint and its successor labelle, and on the Java library dymo-print. Embedded fonts, icons and libraries are listed in THIRD-PARTY-NOTICES.md.

DYMO and LabelManager are trademarks of their owners. This project is not affiliated with DYMO.

Licence

Apache License 2.0. Third-party parts keep their own licences: see THIRD-PARTY-NOTICES.md; the device lists them at /licenses.html (linked from the settings, System).