Lego Smart Play: Patent applications and FCC documents reveal the technology

Contents

At CES, Lego unveiled its new Smart Play system – according to the manufacturer, the "biggest innovation" since the introduction of minifigures in 1978. Ten years of development and 25 patents are said to be incorporated into the technology, which is intended to "bring Lego sets to life": a 2x4 brick with integrated electronics recognizes movements, generates sounds in real-time, controls LEDs, and communicates wirelessly with other Lego bricks – without app compulsion, screens, or external controllers. The electronics are completely hidden within the standard Lego system dimensions.

But is Smart Play really more than just another product from the "Powered Up" series? We delved into Lego's patent applications and documents from the Federal Communications Commission (FCC) to take a detailed look at the technology. The result: Smart Play turns out to be a highly integrated multi-function system with three-axis magnetic tracking, a modular audio engine, and foreign object detection during inductive charging. However, it should be noted: patents describe protected areas and technical possibilities, and the actual implementation may differ. The following summarizes the current state of knowledge from publicly accessible sources.

Empfohlener redaktioneller Inhalt

Mit Ihrer Zustimmung wird hier ein externes Video (TargetVideo GmbH) geladen.

Videos immer laden Video jetzt laden

Ich bin damit einverstanden, dass mir externe Inhalte angezeigt werden. Damit können personenbezogene Daten an Drittplattformen (TargetVideo GmbH) übermittelt werden. Mehr dazu in unserer Datenschutzerklärung.

System Architecture: Smart Brick, Smart Tags, and BrickNet

According to the official Lego press release, the Smart Play system consists of three components: The Smart Brick (2x4 brick) forms the central electronic element with sensors, ASIC, radio, audio, and LEDs. In addition, there are Smart Tags (2x2 tiles, i.e., without studs) as passive ID carriers, which are read by the Smart Brick, and Smart Minifigures, which externally resemble normal minifigures but carry an internal chip for identification.

According to Lego, all elements are fully compatible with the classic System-in-Play. The bricks communicate via a proprietary Bluetooth-based protocol called "BrickNet," which, according to the manufacturer, synchronizes position data and states with low latency between multiple bricks. Lego emphasizes that no app, hub, or cloud connection is necessary during gameplay – the "Lego Smart Assist" app is solely for firmware updates and diagnostics, not for actual gameplay.

Custom ASIC: The Heart in Stud Format

The heart of the Smart Brick is a custom mixed-signal ASIC (Application-Specific Integrated Circuit) with a diameter of only 4.1 millimeters – smaller than a single Lego stud; these have a diameter of about 4.8 millimeters. Lego calls the code running on it the "Play Engine," which, according to manufacturer documentation, interprets movement, orientation, and magnetic fields in real-time and controls audio, light, and radio connections accordingly. The chip was developed in collaboration with Cambridge Consultants (Capgemini) and manufactured by Jabil, according to Lego.

In relevant patents such as WO2025157971A1 ("Magnetic Pose Measurements by Electronic Devices") and EP4593250A1 ("Electronic Device with Multifunction Magnetic System"), this unit is consistently abstracted only as a "processing unit" or "processing module." Details about the CPU architecture, clock speed, memory size, or processor cores used are deliberately left open in the patent specifications. From the functional descriptions, it can only be inferred that the chip must integrate at least the following functional blocks:

• Bluetooth Low Energy Transceiver with full protocol stack (2.4 GHz)
• Multi-channel ADC for evaluating coil signals (amplitude, phase)
• Digital signal processing unit for pose algorithms
• Power management unit with charging control and protection circuits
• Audio synthesizer engine
• Sensor interfaces for accelerometer, light sensor, microphone
• GPIO/PWM for LED control and speaker driver

The patents also mention a "start-up logic" that powers up the processing unit from the inductively received energy and implements voltage and temperature monitoring.

Sensor Suite: Multi-layered Environment Sensing

According to the official Lego documents, the Smart Brick is equipped with a comprehensive sensor package. A multi-axis accelerometer detects movement, tilt, and gestures. According to Lego, the Play Engine is intended to use this data for context-specific reactions – for example, different engine sounds depending on the direction of acceleration or crash effects upon sudden deceleration.

According to the manufacturer, a light sensor or LED array serves not only for light output but also for ambient light and color sensing. This is complemented by a sound sensor that perceives ambient noise.

A technical highlight is the magnetic field sensing: multiple electromagnetic coils measure time-varying magnetic fields of other modules. Patent WO2025157957A1 / EP4591961A1 ("Wireless Interactive Toy Construction Element with Coils") describes a box-shaped building element with six walls and three pairs of parallel side walls – geometrically a classic Lego brick. Inside is a frame element with a set of electromagnetic coils, whose axes are specifically aligned:

• A first coil with its axis parallel to the smallest outer surface (the top of the studs)
• A second coil with its axis parallel to a larger, orthogonal side wall
• A third coil along the third spatial axis

The coil axes are spatially offset and theoretically intersect, but do not physically touch. The patent specifies that the coils on the frame element are wound such that their axes are arranged "distally with respect to" each other and intersect "without touching" – a geometric requirement essential for orthogonal field measurements without crosstalk. This creates a three-axis electromagnetic coordinate system, similar to known tracking systems from medical technology or VR applications.

Lego refers to a "precision copper coil assembly." However, the patents leave the exact geometric parameters (coil diameter, number of turns, inductance, resonant frequency) open.