[Interest] QtBluetooth device connection issue

Blasche Alexander Alexander.Blasche at digia.com
Tue Sep 9 14:42:17 CEST 2014


A simple sdp scan shows you all advertised services. On Linux you can retrieve the list using Bluez command line tools:

hcitool browse <remote_bt_address>

The "Service Class ID List" states the uuid of each service.

I cannot tell you whether btchat is the right tool to verify your dongle's SPP service. It should be able to confirm that you can connect yourself but beyond that it really depends what purpose the SPP fulfills. BtChat assumes that the service takes printable chars and shows them to the user.


--

Alex

________________________________
From: Ramakanthreddy Kesireddy [Ramakanthreddy.Kesireddy at TechMahindra.com]
Sent: Tuesday, September 09, 2014 12:33
To: Blasche Alexander; interest at qt-project.org
Subject: RE: QtBluetooth device connection issue

Hi,

Thanks for your inputs.

Is it possible to retrieve the dongle’s service UUID as we basically would like to connect through SPP though the  service of dongle displays Service: RDA SPP?
I assume btchat is the correct example to verify using BT SPP.

It is a standard ELM327 OBDII Dongle but operates at 12V and power rating is 2 to 5W.

Br,
Ramakanth


From: interest-bounces+ramakanthreddy.kesireddy=techmahindra.com at qt-project.org [mailto:interest-bounces+ramakanthreddy.kesireddy=techmahindra.com at qt-project.org] On Behalf Of Blasche Alexander
Sent: Tuesday, September 09, 2014 12:15 PM
To: interest at qt-project.org
Subject: Re: [Interest] QtBluetooth device connection issue

Hi,

I am going to assume that your dongle's service uses the same uuid and protocol type (rfcomm) as the btchat example. Otherwise this would never work.

My guess is that you have not paired the two devices properly. Your error message is what I get in such cases. Even if one partner is reporting a proper pairing try to redo it and reconnect. This forces both sides to acknowledge the situation.

I am sorry but I cannot make any statements about the state/firmware of your dongle. There are too many dongles on the market as that I could give a statement about yours.


--

Alex

________________________________
From: interest-bounces+alexander.blasche=digia.com at qt-project.org [interest-bounces+alexander.blasche=digia.com at qt-project.org] on behalf of Ramakanthreddy Kesireddy [Ramakanthreddy.Kesireddy at TechMahindra.com]
Sent: Tuesday, September 09, 2014 07:58
To: interest at qt-project.org
Subject: [Interest] QtBluetooth device connection issue
Hi,

Am using Qt 5.3 on Ubuntu 13.10 desktop and tried to run both qmlscanner and bychat example applications
to connect to OBDII dongle.

When I run qmlscanner with full discovery, it gives below service description:

OBDII->
Address: 00:0D:18:00:00:01
Service: RDA SPP
Protocol:168618128

OBDII->
Address: 00:0D:18:00:00:01

But with btchat example, it is unable to connect with logs when we click connect as below:

got click "OBDII RDA SPP"

Connecting to service 2 "RDA SPP" on "OBDII"

Going to create client

Connecting...

Start client

Create socket

ConnectToService done

qt.bluetooth.bluez: void QBluetoothSocketPrivate::_q_readNotify() 21 error: -1 "Resource temporarily unavailable"


Please let me know if there is a problem with dongle(either firmware or port not opened) being used or do we need to use any different UUID to connect to device?

Thanks and Regards,
Ramakanth


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