V.BTTN application

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  • Official comment
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    VSN Mobil Support (Edited )

    1. The Developer Quick Start Guide mentions Link Loss Service (Section 6b). 

    The link loss is controlled by the stealth mode.  So, you’ll need to use stealth mode.  If your customer’s usage profile includes frequent disconnect/reconnect, I would recommend setting the V.BTTN to beep only.  This will reduce current drain on the device.

    2. Battery level.

    a. The V.BTTN device periodically measures battery level using A/D built into the BLE chip.   Depending on when the measurement is taken, the result could be affected by battery droop due to the buzzer, LED and/or BLE chip being active.  The measurement result thus could vary from reading to reading.  So to avoid user confusion, we recommend you design the app to display battery level as a range (e.g. using color code) and not display a numerical percentage.

    Recommended range

    Good/Green > 20%

    Low/Yellow — 10% to 20%

    Critical/Red  < 10%

    b. Avoid constantly reading the battery level


    c. Use the battery notification characteristic and let the V.BTTN notify your application when there is a change in the battery percentage. 


    d. Always use quality coin cell battery (e.g. Energizer, Panasonic, etc.).

     

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    John Developer

    We have now implemented stealth mode. There are cases where we have frequent disconnects/reconnects so hopefully this will help.

    Also, I have done some tests with the connection interval.

    We were using 20 - 40ms but I have now increased it to 300-400ms (min-max).

    If I increase the range above these values we have issues with responsiveness.

    We have not touched the other settings (slave latency and supervision timeout).

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    VSN Mobil Support

    Is 400ms the max connection interval you can set it to?  You should try to get the largest value you can.

    Once you’ve determined the connection interval, then you should look at changing the slave latency to 1.  This essentially allows the BLE chip to skip an interval if there’s no data to send.  So if there are long period of time that the user is not pressing the button, you would have effectively doubled the connection interval.

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