A maker has built CrowdClock festival badges with 16 addressable RGB LEDs and an ESP32 that broadcast local clock ticks via ESP-NOW. Each badge listens for higher ticks from nearby badges, updating itself until the whole group runs synchronized light sequences
When a crowd swells toward the stage, the glow often comes first—wristbands and badges that flash in time with the music. But pairing gear, master controllers, and extra infrastructure are usually part of the deal.
Tony Goacher wanted a different approach. He’s built his own set of syncing festival badges called CrowdClock, designed to get their lights moving in step without any pairing process or additional infrastructure to speak of.
Each CrowdClock badge carries a ring of 16 addressable RGB LEDs. An ESP32 microcontroller drives the lights, bringing built-in wireless capability right out of the box. Rather than rely on a central organizer to coordinate everything, Goacher built the badges to communicate with one another.
The key is ESP-NOW. Goacher uses the ESP-NOW wireless communication protocol so each badge can broadcast its current local clock tick. At the same time, every badge listens for clock ticks coming from other badges in the area. When a badge receives a higher clock tick value, it updates its own current clock tick to match.
In practice. that creates a simple self-correcting chain reaction: badges within radio range sync up automatically over short order. then run their LED sequences in sync. There’s no master designation at all. The devices just all converge to whichever badge has the highest clock value in the area. and then move forward from there.
It’s a neat solution for anyone who’s been stuck watching the glow fall out of rhythm—because there’s nothing to configure, and nothing that has to “start the show.” For people who like tinkering, Goacher has placed files on GitHub for those curious to learn more.
If you’ve ever wondered how those concert wristbands work, that curiosity isn’t new either: the project comes with a reference to how those concert wristbands work as well, along with a video embedded after the break.
ESP32 ESP-NOW RGB LEDs festival badges self-syncing wireless communication microcontroller projects GitHub