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Date:   Sun, 2 Jun 2019 17:58:49 +0100
From:   John Whitmore <arigead@gmail.com>
To:     Emil Lenngren <emil.lenngren@gmail.com>
Cc:     Bluez mailing list <linux-bluetooth@vger.kernel.org>
Subject: Re: Different respones to BLE scan from a Peripheral device?
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On Fri, May 31, 2019 at 04:30:38PM +0200, Emil Lenngren wrote:
> 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

Thank you for that. I'll have a look into that and see if I can't get to the
bottom of this issue.