4 Replies Latest reply on Aug 6, 2018 2:38 PM by Adam Burnett

Android can't reliably connect to Zebra via BLE when BT classic is enabled

Michael Heins Aug 3, 2018 8:06 AM

We have an iOS app that we are re-doing for Android. We typically connect with ZD4xx family printers via wifi, BLE or BT classic, depending on customer requirements. Typically all 3 of those interfaces are active. On iOS we are able to reliably discover and connect to the printers via BLE, but on Android, the connect attempt usually fails. If we disable the BT classic interface on the printer, the BLE connections usually succeed (but that is not a viable solution for us). The behavior is the same with different Android platforms and Android OS versions that we have tried.

Our speculation is that the reason may be that the printer is advertising the BLE and BT classic with the same MAC address on both interfaces, and that this confuses the Android Bluetooth stack. We speculate that if BLE and BT classic were advertising with different MAC addresses, the problem would go away.

Our questions are: Has anyone else has observed this problem? Has anyone found a solution? Is there any way to programmatically set a different MAC address for the two Bluetooth interfaces?

Thank you.

Michael Heins

Re: Android can't reliably connect to Zebra via BLE when BT classic is enabled

Steven Si Aug 3, 2018 11:02 AM (in response to Michael Heins)

Hi Michael,

Do you have a test app to share that we can reproduce this problem? We would like to see if this happens during the discovery or happens after connected.
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- Re: Android can't reliably connect to Zebra via BLE when BT classic is enabled
  
  Michael Heins Aug 6, 2018 8:13 AM (in response to Steven Si)
  
  Our Android guy used an Android app called "nRF Connect" to test it independently of our BLE app code.
  
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  - Re: Android can't reliably connect to Zebra via BLE when BT classic is enabled
    
    Steven Si Aug 6, 2018 2:06 PM (in response to Michael Heins)
    
    ...but on Android, the connect attempt usually fails. ...
    What specific device and Android version do you use when you observed this problem? I've tried nRF Connect on Zebra TC56 and was able to connect to the ZD410 over BLE straight away.
    
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    - Re: Android can't reliably connect to Zebra via BLE when BT classic is enabled
      
      Adam Burnett Aug 6, 2018 2:38 PM (in response to Steven Si)
      
      Hi Steven,
      
      I'm the Android guy referred to previously. I have tested this on the following platforms:
      Kindle Fire 7 (Android 5.1.1).
      Google Pixel XL (Android 8.1).
      Lenovo TB-X103F (Android 6.0).
      
      I initially discovered this when placing our Zebra ZD410 into "Smart Only" mode in the connection parameters and turning off the WiFi. The Zebra Printer Setup app (Android) fails to discover or connect when the connection is forced over BLE (i.e. smart mode).
      
      On a separate note, from nRF Connect I can connect to a printer on all of the platforms listed above fairly regularly when I put the printer into "Smart Only" mode. It seems the problem occurs when both BLE and Classic are enabled for a printer.
      
      Thanks for your help Steven,
      Adam Burnett
      
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