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From:   Emil Lenngren <emil.lenngren@gmail.com>
Date:   Fri, 31 May 2019 16:30:38 +0200
Message-ID: <CAO1O6sdSBPXR-h1sfzCF6zsAv-a5Bexd2s8X7wDQwrghrvuCEA@mail.gmail.com>
Subject: Re: Different respones to BLE scan from a Peripheral device?
To:     John Whitmore <arigead@gmail.com>
Cc:     Bluez mailing list <linux-bluetooth@vger.kernel.org>
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Hi John,

Den fre 31 maj 2019 kl 14:27 skrev John Whitmore <arigead@gmail.com>:
>
> Hello all,
>
> I'm running on two identical embedded Linux Gateway devices, both on
> Ubuntu 16.04 and Bluez 5.37. That's certainly an older version, but
> it's part and parcel of that version of Ubuntu. I'm having an issue
> where the two identical gateway devices are getting different
> responses from a BLE scan, and can't figure out what would be the
> cause. In both cases it's the same peripheral device, a TI CC2650
> device. On one gateway I get a truncated response with just the MAC
> address and in the other I get the MAC address plus the description
> string "CC2650.."
>
> [bluepy.btle:37] Got: 'rsp=$scan\x1eaddr=b546C0E530068\x1etype=h1\x1erssi=h43\x1eflag=h0\x1ed=b020105030280AA06FF0D0003000011094343323635302053656E736F72546167051208002003020A00\n'
>
> [bluepy.btle:37] Got: 'rsp=$scan\x1eaddr=b546C0E530068\x1etype=h1\x1erssi=h28\x1eflag=h0\x1ed=b020105030280AA06FF0D00030000\n'
>
> I'm probably going to have to get a Bluetooth sniffer device to trace
> this issue, but if anybody had any idea what this would be the case,
> I'd love to hear.
>
> Perhaps even though the Gateways are running the same Hardware and
> Software there might be a Hardware difference in the chipset used or
> something. It's all I can think of. Hopefully get something to help
> diagnose this issue.
>
> In those two messages there is a difference in RSS, is that signal
> strength and could that be the issue? Have to open things up.
>
> Thanks in advance for any help, and apologies I'm at the wrong end of
> a learning curve.
>
> John

You could try running btmon in a terminal to show the HCI traffic.
There you should see the raw advertising packets in form of LE
Advertising Report packets. You should see both ADV_IND packets as
well as SCAN_RSP packets. Maybe the software doesn't always combine
them and that's why you get different results. And yes RSSI is signal
strength.

/Emi