Sound-programmable e-paper badge with USB serial programming and 125 kHz RFID emulation

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GGtag is a compact e-paper badge designed for versatile programming capabilities. It can be programmed with the web interface, USB serial, or sound! GGtag is centered around the RP2040 microcontroller and features a 3.52 " e-paper display. GGtag supports USB serial programming and emulation of 125 kHz RFID tags (ASK and FSK), providing flexibility for various applications.

Web Interface for Design and Programming

GGtag boasts a web interface that simplifies the creation, editing, and sharing of tag designs. Users can program these designs directly onto the device through our web browser. The interface supports a range of elements, including QR codes, images, and FontAwesome icons. Whether using sound or USB, GGtag can be programmed through this web-based interface.

A Hub for Creativity

As an addition to its practicality, GGtag serves as a platform for experimentation with data-over-sound and e-paper displays. All resources, including reference implementations, hardware specifications, and documentation, are openly accessible, facilitating adaptation for various custom applications.

Programming GGtag

GGtag supports two programming modes: sound and USB serial. Sound programming requires inserting a CR2032 battery into the holder and switching to the BATT position. For USB serial programming, GGtag can be connected to a USB host and switched to the USB mode. Both modes are compatible with the web interface hosted at, accessible through standard HTML browsers.

Sound Programming with GGtag

Programming GGtag via sound is achieved using the custom ggwave library. In this video demonstration, multiple GGtags are programmed simultaneously using a mobile phone. After the initial programming, GGtag enters deep sleep mode, requiring manual activation by pressing the side button. To conserve battery life, it is advisable to switch back to USB mode after programming.

USB Serial Programming for GGtag

For USB serial programming, GGtag relies on the Web Serial API through the web interface at Compatibility extends to modern web browsers, such as Chrome and Edge, with mobile Chrome on Android also supported. This demonstration illustrates the use of a Pixel 5 phone for USB serial programming.

Emulation of RFID Tags

GGtag’s capabilities include the emulation of 125 kHz RFID tags, achieved through an ATtiny85 MCU and the avrfid firmware. Upon receiving an RFID command, GGtag generates the corresponding avrfid firmware and programs the ATtiny85.

RFID Emulation read by Flipper Zero

RFID Emulation read by USB RFID reader

Features & Specifications

GGtag is equipped with the following features and specifications:


A comparative analysis highlights GGtag’s key attributes in relation to similar products in the market, considering factors such as weight, display size, resolution, connectivity, and more. This provides a comprehensive overview of GGtag’s strengths and unique features.

GGtagBadger 2040WAdafruit MagTagInkplate 2Badgy
Weight32 g 32 g unknown unknown 29 g
Display Size3.52 " 2.9 " 2.9 " 2.13 " 2.9 "
Resolution360 x 240 296 x 128 296 x 128 212 x 104 296 x 128
ConnectivityUSB Serial, Sound WiFi WiFi WiFi, Bluetooth WiFi
USB-C AvailableYes No Yes Yes No
Open SourceYes No Yes Yes Yes
Web EditorYes No No Yes No
Passive RFIDYes No No No No
Runs on USB PowerYes Yes Yes Yes Yes
Runs on CR2032 BatteryYes No No No Yes
Battery Life2-3 days days weeks months days

Support & Documentation

Extensive support and documentation are readily available through our public GitHub repository. Both firmware and hardware are open source and licensed under the GPL v3, promoting transparency and flexibility. Detailed hardware specifications can be found in the hardware directory for those interested in exploring the technical aspects.

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Produced by Eurolan in Sofia, Bulgaria.

Sold and shipped by Crowd Supply.


Sound programmable e-paper badge with RFID

$45 $8 US Shipping / $18 Worldwide

About the Team


Sofia, Bulgaria  ·

We design and manufacture quality networking equipment - media converters, Ethernet switches, IPTV STBs. Our products are designed by our own R&D team and manufactured in our factory, based in Sofia, Bulgaria.

Hristo Gerenski
Georgi Gerganov

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