2 Replies Latest reply on Dec 5, 2017 12:07 AM by deniisthyrion_2934356

    Custom services and characteristics




      I would like to know what is the good approach to structurers custom services and caracteristics :


      What i have actually is :

      2 custom services, let say Custom service A and custom service B

      Custom service A has 6 characteristics

      Custom service B own 11 characteristics


      + generic access service + generic attribute + batterie services


      Does i have to rework that to keep the number of custom services and caracteristics lower ? Does i have to just use 1 service, because 1 custom service for 1 product is just sufficient.

      What the maximum number of services or characteristics that Posc or Proc devices can handle ?


      I had a problem actually with my phone app, when sometimes the connection just fail (it's totally random, and the BLE stack don't even enter in the connection state, but my app catch a connection error, and from HCI log on the phone i have a "connection failed to be etablished (0x3e)".



      Other thing that i don't understand is about customm uuid (i have read the Cypress app note about UUID but it doesn't help me).


      What i have done actually is to generate for each service or caracteristic a random UUID made by a generator, is that a correct way ? I have seen that in other device some generate a base UUID and have some incrementations of a part of the UUID. Cypress app note doesn' t help me because my companie doesn't own an UUID from sig.


      Thanks for you help in advance.

        • 1. Re: Custom services and characteristics



            You can use multiple custom services and characteristics. To estimate the maximum number of services and characteristics which we can declare, is not straight forward because it will depend on the BLE stack GATT Database memory.


          Please refer this document -> http://www.cypress.com/file/140826/download  for Generating Custom UUID.




          • 2. Re: Custom services and characteristics



            Thanks for your answers, sorry for my let answer..


            To my first question it's more to know how it's usually made, than estimate the max number possible (my question was no clear about that). Does it have a notable influence of the time make by a phone for discovery for exemple ? Just to know if it is best suited to use 2 big large characteristics or 100 characteritics for example? Fact that most of the exemples just use a few ones.



            About the document it's still not clear for me

            Is is ok to generate a different random UUID for each caracteritistics or service, or just generate random base UUID and make a logic organization with the rest of the UUID ?

            There ise different UUID generators which one does i have to use ?