Zebra Bluetooth Unpairing

I'm starting on integrating bluetooth printing into our Android app and I'm looking forward and seeing a potential issue with unpairing.  We are currently using TC70 & TC70Xs to connect to ZQ520 printers.  Using the linkos library an the emdk it seems fairly straight forward to search for unpaired devices and connect to them.  The issue that I see, because we have multiple devices, is what happens when a different device wants to use an already paired printer to print?  I can see issues where the device that originally paired with it is not readily available to open bluetooth settings and unpair, is there a way to unpair the printer from the printer so it can be paired to a new device?

I'm also aware of the insecure connection that allows you to print without pairing, but for simplicity in our app I'd prefer to have the printer paired once, and then not have to select the printer each time the user wants to print something.

Anonymous (not verified)
Hi, you can have multiple

Hi, you can have multiple devices paired with the printer at once, you just can't have multiple devices connected (and printing) to the printer.  That being said, if you want to unpair a printer from the TC70/TC70X the EMDK does also have a scanAndUnpair API: ScanAndPairManager (app API)

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Charles Berlin
"you can have multiple

"you can have multiple devices paired with the printer at once"

Is there a limit to this?

Also the scanAndUnpair method seems to unpair from the device that you call that from, what I"m worried about is having several devices that I do not have access to (because they broke or get swapped out of rotation) be paired to the printer preventing new devices from pairing.  So I guess a more direct question is is there a way to manage (remove) the paired devices from the printer and do I need to be able to do this if multiple devices are allowed to pair.

Thanks.

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Anonymous (not verified)
If there is a restriction in

If there is a restriction in the number of simultaneously paired devices it would be a restriction of the Bluetooth protocol or hardware limitations.  There is a lot of conflicting information on the internet about this but the following SO post looks good & accurate: How many devices can be hooked up to one PC Bluetooth adapter at a time? - Super User .

The printers are acting like any other BT peripheral in this scenario.

I'm not an expert on the print size but the ZQ520 documentation https://www.zebra.com/content/dam/zebra/manuals/printers/common/bluetooth-ug-en.pdf  and https://www.zebra.com/content/dam/zebra/manuals/en-us/printer/zq500series-ug-en.pdf  do not refer to unpairing so I do not believe this would be an issue.

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Charles Berlin
Right, I read those manuals

Right, I read those manuals and didn't see anything about unpairing so that was why I raised the issue here.  Is there a better place to get more detailed information about those specifics?

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Anonymous (not verified)
Hi Joseph, The Zebra printers

Hi Joseph, The Zebra printers all follow Bluetooth standards for SPP devices.  The printers are always in slave mode. The detailed documentation is provided by Bluetooth SIG. According to my understanding of these standards, pairing and un-pairing should be initiated from the master device - that is the Android phone.   

For specifics of what you are asking about, the bonding feature allows 16 stored pairings.  If you pair with more the oldest pairings are removed.  You can also send commands to clear the bonding cache or turn off bonding. 

! U1 setvar "bluetooth.bonding" "off"<cr>

! U1 do "bluetooth.clear_bonding_cache"<cr>

Keep in mind, this is not true unpairing - the Android devices will still show paired until they try to connect to the printer.

If it helps, we have many customers who have printer sharing use cases.  We have never run into an issue where the printer was unable to pair with a device because it had too many other pairings saved.

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