IoT for retail & sensors

  • Hi Guys,

    In retail, you often have several independent sensors or systems, eg: a 'bing bong' when a customer opens the front door, an alarmed rear fire door to alert staff of run away stock theft, a microphone and PA speaker system "Customer announcement, the store will be closing in 10 minutes".

    I run a hardware store and I want to combine all of this in to one automated solution, and I can't find anything off the shelf ? I was hoping there was an android app out there that listened for sensor inputs and then played audio recordings but I can't find anything like that?

    The store has an audio amplifier and microphone to evenly distribute music throughout the store, and it has several unused inputs which, when played, interrupt the music. For example the microphone for staff announcements is one input.

    The idea:
    Install sensors that trigger audio recordings which can be played over the store's sound system using one of the 3.5mm Auxiliary In ports on the store music amplifier.

    I would like:

    1. IR Line Sensor at the cash register queue that can be turned on/off depending on if the store is busy or not (eg via a on/off switch operated by a staff member).
      Example: Store is quiet, staff are busy at the back of the store re-stocking shelves. Customer walks in to the cash register area and breaks the IR beam and triggers an audio message "Staff Announcement, customer waiting".
    2. Contact sensor on the front and rear doors to play an audio recording when triggered
    3. Scheduled recording for the benefit of staff and customers.
      EG: 5 minutes before opening "Staff Announcement, this store will be opening in 5 minutes"
      EG: 10 minutes before closing "Customer Announcement, this store will be closing in 10 minutes"

    Any suggestions? I was thinking of using an old Pixel 1 android phone, with an app, and connect the phone to the amp using the headphone jack, but what app, and how the sensors would talk to the app is the question?

    Thanks in advance !! 🙂

  • Mod

    I built a sensor for the front door of a store. The code is available at

    I installed Domoticz on a Raspberry Pi and configured Domoticz to play a sound (through the audio jack) whenever the sensor was triggered. The sound was an mp3 file.

    It is possible to configure Domoticz to play different files depending on which sensor was triggered.

    I have no experience with Android but there are probably was to do something similar on a phone.

  • Hardware Contributor

    Hello @jones87 there are some MP3 shields and modules on AliExpress with jack output, it feels easier to make a node that will trigger different mp3 files on an sd card based on activation of switches, than using those instead of relying on an old smartphone that doesn't get security updates anymore, an app etc...
    Search for VS1053 on AliExpress for some examples.

  • I also suggest using MP3 shields and modules with jack output.

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