4 Replies Latest reply on Dec 9, 2016 10:26 PM by gadec_1181136

    Device UUID

    gadec_1181136

      Can anybody tell me more about Device UUIDs? This may also refer to Project, Application or Peripheral UUID. I know it's there because It comes up at the top before the Device Name in Light Blue. I can't find anything in Wiced Smart SDK about how to set it and whether or not it should vary from device to device. Currently, I'm initialising units by running Anaren Programmer first, and I think this is setting it. I then use Wiced Smart SDK to program my application, and also use it to set unique BT Mac address, but I can't see anything that affects this devce UUID.

        • 1. Re: Device UUID
          ChristopherA_76

          Hello Gary,

           

          The relevant section of the BT specification you should check is Service Discovery Protocol for an explanation on how UUIDs are used and defined in Bluetooth. They are used to describe particular services and their characteristics - in very basic terms think about it a little bit like port numbers on a PC network, with which you might be more familiar.

           

          UUIDs are 128 bit numbers used to look up attributes but they can be shortened to 32 or 16 bit forms.

           

          Services defined by the Bluetooth standards have UUIDs assigned to them, but you can add your own.

           

          For example, if you want to define a new service, you can allocate your own UUID to represent it. There is a mechanism to minimise the chance of a clash of UUIDs. You can generate a random number for now if you're just testing - you should check the BT standards how to build the correct UUID for an existing service.

           

          Gregg

          • 2. Re: Device UUID
            gadec_1181136

            Thank you ChristopherA_76. This is very clear and comprehensible.

             

            However, I do not think the UUID I am referring to is a Service UUID. I have created my own service, which contains 3 characteristics. I have used IEEE to generate four 128-bit UUIDs - one for the service and three for the characteristics. I can clearly see these, along with the standard services of Device Information and Battery Service I am also using (these have their own, shorter, standard UUIDs). I have included these in my code in just the same way as is clearly shown in Wiced Example projects.

             

            The UUID I am referring to is called a Peripheral ID by LightBlue, and seems to relate to the device, rather than any particular Service offered by the device. The UUID value is not one that I have specified anywhere in my code. This is why I suspect it is put in by Atmosphere Programmer when I use that to initialise my hardware.

             

            Because my app uses the Service UUID to recognise that this is the correct peripheral, it doesn't seem to matter what this Peripheral ID is, but I am not entirely happy that I am generating and communicating a UUID code over which I have no apparent control. If I'm worrying about nothing, that's fine - I'd just like to understand.

             

            Gary

            • 3. Re: Device UUID
              MichaelF_56

              Adding mida_2165396 and userc_5854 of Anaren

              • 4. Re: Device UUID
                gadec_1181136

                I think I've finally got the answer I need on this. The only UUIDs you need to be concerned with are the Service and Characteristic UUIDs  described by ChristopherA_76 above. The Project UUIDs I mention are not relevant to anyone developing with Wiced SDK. They relate only to projects generated by some other tools.

                 

                What is important is understanding the Device/Peripheral UUID displayed in LightBlue, as I do not recognise it, even on my own products. The reason is that it's generated by iOS. Instead of displaying the Bluetooth MAC address for a particular device, it assigns this UUID to that device, and hides the MAC address. I believe that Android does not do that.

                 

                It's some relief to learn this, as I was quite perturbed by a code being displayed and not having any idea where it came from. As I use the facility in 'Make Target' to enter different MAC addresses for every device in the 'Target Name' field, I will continue to get different UUIDs for every device from iOS.

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