Open Source Badge - Bitcoin Amsterdam 2026 Edition
Limited edition of 100 units. There will be no second batch.
Description
The badge of Bitcoin Amsterdam 2026, designed and built by us. An 18 LED ₿, two TX/RX LEDs and three buttons on a board that rides on a LilyGO T-Display-S3 (ESP32-S3 with a 1.9" 170x320 colour screen), inside a 3D printed case and ready to hang from its lanyard.
Limited edition of 100 units. Part of the run was sold at the conference in Amsterdam and what is left is here. There will be no second batch.
Proof of Peer
Put two badges together, press PEER on both and they swap contact cards over ESP-NOW, with no internet in between: name, X, Telegram, npub, Lightning address and PGP fingerprint. Badges near you announce themselves, and everyone you met can be downloaded as vCard or CSV.
Zaps
Give it your npub and a WiFi and the ₿ lights up every time someone zaps you. It listens to the Nostr relays damus, primal and nos.lol: purple for a Nostr zap, gold for a Lightning payment.
NerdMiner inside
Solo mining at about 140 kH/s with the SHA-256 hardware of the ESP32-S3, while you are looking at its screen. Out of the box it points at our pool; put your own Bitcoin address in and the block would be yours.
Seed Lab
Watch a BIP39 seed being born from dice or coin tosses, with the radio off. It is there to learn how it works: for real money use an offline signer such as the Seeder.
Open source, and yours to change
MIT firmware on GitHub and a web flasher at flasher.bitronics.store, so you can update it or write your own. Setup is done from the phone: a long press on MODE opens its own WiFi and a page at badge.local with your profile, the WiFi, your npub and the list of people you met.
In the box
- The badge, assembled and tested, in its 3D printed case
- A 1100 mAh LiPo battery, already fitted inside
- The lanyard
Specs
- LilyGO T-Display-S3: ESP32-S3, 1.9" IPS 170x320, WiFi and ESP-NOW
- 18 WS2812B RGB LEDs forming the ₿, plus TX and RX LEDs
- Three buttons (PEER, MODE, SEED), Qwiic port and a switch that really cuts the battery
- LiPo 603450 of 1100 mAh: around 12 hours with power saving, around 5 hours with everything at full
- Black PCB with ENIG gold finish, 100 x 70 mm; 3D printed case of 104 x 80 mm, about 1 cm thick
- Charges and flashes over USB-C
THE OPEN SOURCE BADGE
Bitcoin Amsterdam 2026 · Limited edition of 100
The Open Source Badge is the badge we designed and built for Bitcoin Amsterdam 2026. A black board with an ENIG gold finish carries a LilyGO T-Display-S3 (ESP32-S3 with a 1.9" colour screen), 18 RGB LEDs drawing the ₿, three buttons and its own 1100 mAh battery, inside a 3D printed case with two tabs for the lanyard.
It swaps contact cards with other badges, lights up when someone zaps you, mines solo and shows how a seed is born. Only 100 were made and there will be no second batch.
Current version
Open Source Badge rev0.9 · LilyGO T-Display-S3 · firmware v1.0.0
Drag it to turn it around
See what it does
This is the badge running the same effects as the firmware inside it. Press its buttons, or pick a mode.
A badge that keeps working after the event
It is a small ESP32-S3 computer with a colour screen, 20 LEDs and three buttons, running on its own battery for around 12 hours. Every line of its firmware is public, so it can do what we built it for or whatever you decide to make of it.
Set up from your phone
A long press on MODE opens the badge's own WiFi and a page at badge.local: your name, X, Telegram, npub and Lightning address, the WiFi it should use, and the people you met, ready to download as vCard or CSV.
What it can do:
Proof of Peer:
Put two badges together and press PEER on both: they swap contact cards over ESP-NOW, with no internet in between.
Nostr zaps:
Give it your npub and a WiFi and the ₿ lights up in purple every time someone zaps you on Nostr.
Lightning:
Its screen shows your Lightning address as a QR, so anyone next to you can send you sats.
NerdMiner inside:
Solo mining at 140 to 160 kH/s while its screen is on, with live hashrate, shares and best difficulty.
Seed Lab:
Watch a BIP39 seed being born from dice or coin tosses, with the radio off. Made for learning, not for real money.
Open source:
MIT firmware on GitHub and a web flasher at flasher.bitronics.store to update it from the browser.
Play with it:
Write your own LED effects and screens, or plug sensors into its Qwiic port. Buttons, LEDs and screen are yours to program.
See it in action
The whole story of the badge on our YouTube channel: how the idea came up, what is inside it and every function working on the real thing, from Proof of Peer between two badges to the NerdMiner and the Seed Lab.
Jump to
Open Source Badge resources
Everything you need for your badge: the user guide and, since it is open source, the firmware, the flasher and how we built it.