How Mobike’s Electronic Locks Play Christmas Songs: Inside the IoT Architecture

After a rider discovered a Mobike bike playing a Christmas tune when scanning the QR code, the author investigated the technology behind this surprise.

Mobike’s electronic lock system consists of a central control unit, GPS module, 2G wireless communication module, electromechanical lock, battery, kinetic‑energy generator, charging management, and an onboard accelerometer. When a user scans the QR code, the bike’s communication module downloads an audio file from the cloud server and plays it through the bike’s speaker.

The unlocking workflow works as follows: the central control unit connects to the backend management system via the wireless module, sends the GPS‑derived location to the server, receives an unlock command, and activates the electromechanical lock. After the ride, the lock reports its status back to the server, which then finalizes billing.

Early generations of Mobike bikes used a purely kinetic generator, making pedaling laborious. The second generation added solar panels to the basket, reducing rider effort. Images illustrate the lock’s internal modules and the overall architecture.

Mobike’s platform now covers over 50 cities, more than 3 million smart bikes, and generates over 1 TB of data daily, forming the world’s largest IoT platform for shared mobility.

Understanding this system reveals how a simple QR scan can trigger both unlocking and a festive song, showcasing the integration of cloud services, IoT hardware, and user experience in modern shared‑bike operations.