Smart home control app opened on a smartphone
© Stanisic Vladimir – stock.adobe.com

The Internet of Things in Your Hand

IoT Device Control and Configuration via Inductive Data Transmission

Inductive data transmission involves employing the magnetic coupling of adjacent circuits specifically to transmit data between two devices. At low frequencies, loudspeaker components are also capable of such coupling effects. From this we developed a solution for controlling devices easily using a smartphone: users simply select the desired device configurations in an app, which then transmits them via the phone’s speakers to, say, their coffee machine, heating system or fitness equipment. With little effort, this turns smartphones, together with the appropriate apps or web applications, into universal control units for any IoT device.

How does device control via loudspeaker work?

No additional transmission hardware
required

By using frequencies at the very edge of the human hearing range, the phone’s loudspeaker itself becomes a transmitter.

Inductive data transmission

Data is transmitted unidirectionally from the smartphone loudspeaker to the IoT device – by magnetic coupling between the integrated inductor in the loudspeaker and the resonant circuit connected to the IoT device’s microcontroller.

Minimal extension at the receiver

The integration of a simple resonant circuit on the microcontroller is sufficient to receive the magnetically transmitted signals, which are then digitized and processed with an appropriate software decoder. This means no microphone is necessary on the receiving end.

The technical details

  • Frequency
    18.5 kHz
  • Modulation type
    MSK (minimum shift keying)
  • Symbol rate
    1200 baud/s
  • Range
    5 to 20 cm
  • Standby power consumption
    about 20 μA (depending on the microcontroller)

Feature upgrade for smart devices

Inductive data transmission via loudspeakers gives every smart device a simple and useful feature upgrade.

Easy integration

Cost-effective and space-saving

  • Minimal hardware extension
  • No additional radio module, no microphone

Greatest possible freedom in product design

  • No need for keys, displays or interfaces
  • Metallic housings and water- and dustproof designs possible

No compatibility
problems

  • Works with any smartphone or tablet
  • Via the speaker in license-free frequency spectrum

Effortless connectivity

No
pairing

  • Devices can be addressed immediately without first coupling with the smartphone
  • Limited range protects against unauthorized external access

Rapid
availability

  • Easy access, for example via a QR code on the IoT device
  • Ideal for frequently changing users

Direct communication with the IoT device

  • “Talk” to the device with no gateway or Internet connection
  • Or: use data transmission via loudspeaker to register IoT devices in the network (“device provisioning”)

Virtual user interface

Simplified
device use

  • Virtual user interface with access to all device functions
  • Intuitive control via app or web interface

Extended
operability

  • Control via smartphone as additional operating option
  • Also for additional functions or special settings

Simplified configuration for manufacturers

  • Can be used to transmit manufacturer-side configuration settings
  • Even for several devices simultaneously and through packaging

How you can use the technology

Do you want to make it as easy and convenient as possible for the users of your smart products to adjust all device settings while avoiding the complex integration of a radio module? Then inductive data transmission via loudspeaker is the ideal solution.

Under the name “Magnolinq”, the patented technology is available through LZE GmbH as a product-related implementation. An evaluation kit is also available, with which Magnolinq can first be integrated into a product prototype for testing.

LZE GmbH is part of a joint initiative of the Fraunhofer Institutes for Integrated Circuits IIS and for Integrated Systems and Device Technology IISB with Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU).