# GGtag (Eurolan)

> An e-paper badge with programmable RFID features.

- **Category:** Wearables
- **Availability:** Listed by maker
- **Price:** US$45, checked 2026-09-15
- **Good for:** Program an e-paper badge using sound or USB.
- **You'll need:** A computer or phone for programming; USB or a coin cell.
- **Trade-off:** RFID emulation support does not cover every tag system.
- **Page:** https://gadgets.sh/devices/ggtag/

## Where to buy

| Shop | Status | Link |
|---|---|---|
| Crowd Supply | Orderable | https://www.crowdsupply.com/eurolan-ltd/ggtag?utm_source=gadgets.sh&utm_medium=referral&utm_campaign=ggtag&utm_content=api |

## Blueprint

**Open hardware.** rgerganov (designer) and Eurolan (manufacturer) publish the full ggtag schematic, Gerbers, and BOM in their own GitHub repo under GPL-3.0, alongside the firmware.

### Design files

- schematic: [Schematic (PDF)](https://github.com/rgerganov/ggtag/blob/master/hardware/ggtag-schematic.pdf) (PDF)
- gerbers: [Gerbers + drill files, board rev 1.0 (ZIP)](https://github.com/rgerganov/ggtag/blob/master/hardware/ggtag-rev10.zip) (ZIP)
- bom: [Bill of materials (PartList.txt)](https://github.com/rgerganov/ggtag/blob/master/hardware/PartList.txt) (CSV)
- datasheet: [E-paper panel datasheet (PDF)](https://github.com/rgerganov/ggtag/blob/master/hardware/epd-datasheet.pdf) (PDF)

### Source repositories

- [rgerganov/ggtag](https://github.com/rgerganov/ggtag) — hardware, GPL-3.0, ★343

### Key parts

| Part | Role | Datasheet |
|---|---|---|
| RP2040 | MCU | https://datasheets.raspberrypi.com/rp2040/rp2040-datasheet.pdf |
| 3.52-inch e-paper panel (360x240) | display | https://github.com/rgerganov/ggtag/blob/master/hardware/epd-datasheet.pdf |

_Notes:_ Confirmed via gh api tree + blob fetch (200s). hardware/README.md states verbatim: 'This directory contains schematic diagram, parts list and Gerber files ... entire hardware design is made by Eurolan.' Downloaded and unzipped ggtag-rev10.zip locally: 12 Gerber/drill files for board rev 1.0. pdftotext on the schematic PDF confirms RP2040 as the main MCU. A WebSearch summary of the Crowd Supply page also mentions an ATtiny85 running avrfid for 125 kHz RFID emulation. That is unconfirmed in the schematic text and has no reachable datasheet (microchip.com returned 403, and the Mouser mirror failed), so it is left out of parts.

## Specifications

### Compute & display

| | |
|---|---|
| Controller | Raspberry Pi RP2040 |
| Flash | 2 MB |
| Display | 3.52-inch e-paper; 360 × 240 pixels |
| Weight | 32 g |

### Programming & radio

| | |
|---|---|
| Audio input | PDM microphone; ggwave data-over-sound programming |
| Wired programming | USB-C serial and Web Serial |
| RFID | ATtiny85 running avrfid; passive 125 kHz ASK/FSK tag emulation |
| Wireless networking | No Wi-Fi or Bluetooth radio listed |
| Editor | Browser editor for text, images, QR codes and Font Awesome icons |

### Power & open files

| | |
|---|---|
| Power | USB or CR2032 coin cell; battery switch and wake button |
| Image retention | E-paper retains its image without power |
| Battery operation | Maker comparison lists 2–3 days active; this is not an always-on screen refresh claim |
| Licensing | GPLv3 hardware and firmware; design files published |

## Firmware & community

- [EPDiy E-Paper Controller](https://github.com/epdiy/epdiy) — High performance driver framework for low-latency parallel E-Paper displays and interactive conference badges.

## Documentation

- [Maker specifications and product details](https://www.crowdsupply.com/eurolan-ltd/ggtag)
- [Badge editor](https://ggtag.io/)
- [ggwave library](https://github.com/ggerganov/ggwave)
- [GitHub repository](https://github.com/rgerganov/ggtag)
- [hardware directory](https://github.com/rgerganov/ggtag/blob/master/hardware)

---
Source: gadgets.sh · https://gadgets.sh/devices/ggtag/ · JSON: https://gadgets.sh/api/v1/devices/ggtag.json