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From:   Alain Michaud <alainmichaud@google.com>
Date:   Tue, 26 May 2020 10:57:36 -0400
Message-ID: <CALWDO_W+8SDCOn_b_4_FB-KR43xjyYB8u+kSgQ1YVx1Mp_FG=g@mail.gmail.com>
Subject: Re: UUIDs for every single physical peripheral's service and characteristics?
To:     Christopher de Vidal <cbdevidal.jk1@gmail.com>
Cc:     BlueZ <linux-bluetooth@vger.kernel.org>
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Hi Christopher,

The term "unique" will vary based on context.  In the context of a
Gatt Service and Characteristic, it is intended to uniquely identify
the "contract" defined by the service/characteristics.  For example a
Temperature Service would have a UUID that universally defines the
contract/interface defined by that service.

So for your custom service, you'll need to define a set of 20 128 bit
UUID (16 bit uuids are reserved for SIG defined uuids) that uniquely
identify the contract that's defined by your service/characteristics.
The devices can uniquely be identified/addressed by their respective
addresses.

I hope this is helpful.

Thanks!
Alain

On Tue, May 26, 2020 at 10:38 AM Christopher de Vidal
<cbdevidal.jk1@gmail.com> wrote:
>
> Help a newbie? I'm seeking to build a niche product for sale, a
> Raspberry Pi-based device which during the initial setup acts a BLE
> peripheral. (Python using dbus to Bluez.) It has a single service and
> 19 characteristics. I get that the first "U" in UUID stands for
> unique. Must that be unique among each physical product, or may it be
> unique among the product line?
>
> So if I sell 1,000 units (which would be a success), would I need to
> obtain 1,000 service UUIDs and 19,000 characteristic UUIDs? Or just 20
> total, for the entire product line?
>
> The goal is so that the iOS/Android app can have that pre-set in the
> code and quickly discover the device, pair it automagically.
>
> I suppose the risk is of a conflict of two similar devices which are
> in the same vicinity of the phone, and both set into peripheral mode
> at the same time. But that would be a minimal risk which I could
> accommodate for.
>
> Christopher de Vidal
>
> Would you consider yourself a good person? Have you ever taken the
> 'Good Person' test? It's a fascinating five minute quiz. Google it.