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JustTec | Upgrade for the shopping cart

Digital deposit lock revolutionizes stationary retail trade

Who doesn't know this situation: You're standing in front of a shopping cart at the supermarket and have neither a coin nor a shopping cart chip with you. No chance of getting a shopping cart - unless you could use your smartphone to borrow one very easily and uncomplicatedly.


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JustTec GmbH approached m2m Germany with precisely this specific project - to launch an automatic shopping cart lock that can be unlocked via smartphone and app. The basic idea for the smart deposit lock already existed. m2m Germany was specifically asked to develop a corresponding electronic assembly for the shopping cart lock, consisting of hardware and firmware. In addition, the firmware required for communication with the smartphone and for sequence control of the unlocking of the shopping cart lock was to be developed.


The radio unit/board integrated by m2m Germany is based on a Bluetooth Low Energy module from the manufacturer Laird Technologies, which has an NFC device interface. The NFC interface acts like a readable and writable NFC TAG. The smartphone app reads the NFC TAG to determine whether it is a shopping cart and then writes the command to open the lock to the NFC TAG.

The deposit lock works via smartphone. Shoppers hold their cell phone over the lock to unlock it. Communication takes place via near field communication (NFC). NFC is an international transmission standard for the wireless exchange of data over short distances (10-20 cm). As a rule, all common smartphones are equipped with the technology ex works. In the JustTec app, the "Unlock" button is selected and the deposit lock opens. In this way, shoppers no longer need to search for small change to fetch a shopping cart.

In particular, the platform:

  • Be compatible with the app
  • do without coins
  • have integrated radio solution

Whatever it takes:

  • Time saving for buyers
  • automatic trolley lock
  • Smartphone compatible

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