Tuesday, July 25, 2006

Bluetooth is "busy"

One of the things I have not been able to get up and running, is the Bluetooth connection to my PC. I'm wondering if anybody out there can help me on this one.

Let me first share a few things I did find out.

First, on the Bluetooth menu, make sure Bluetooth is turned on in the NXT brick.

Now we'll try to connect to the NXT using Windows XP Professional SP2. Using "Start > Connect To > Bluetooth Network Connection" does not work, because the NXT does not support the higher level Bluetooth functionality. Connecting from the NXT to the PC also doesn't work, because SP2 by default turns Bluetooth auto-discovery off. To turn auto-discovery on, navigate to "Start > Control Panel > Bluetooth Devices". Under the tab "Options", you'll find a checkbox to turn on Discovery. From the "Devices" tab, you can "Add" devices, and this finds the NXT perfectly. Type in the same passphrase, and you have a connection.

Once auto-discovery is turned on, you can also do the connection from the NXT menu, and it returns the name of the PC perfectly. To program to a connection on the NXT, you need to assign it to a connection (1-3). This is also done from the Bluetooth menu, using the "Search" menu option, but this is where things go wrong. No matter what I try, the NXT brick keeps coming back with the message "line is busy".

By the way, I have no problem connecting my Bluetooth phone (Sony Ericsson T610) to the NXT, and assigning it to a mailbox. I also have no problem connecting the phone to the PC.

To eliminate any already solved firmware issues, I have upgraded my NXT to 1.03, which worked immediately without problem. But it didn't solve the Bluetooth issue.

Anybody out there have any idea's on how to solve this?



At July 26, 2006 3:41 AM , Anonymous david levy said...

I had started seeing this problem right after I stopped and started my NXT-G software.

When trying to initiate the connection from the NXT-G NXT- comm-window. I would do a scan and then connect and always end up with an error dialog after what appeared to be as successful pairing. I then reinstalled my bluetooth software and sure enough I got it to connect again... I then recylced both NXT-G and the NXT device and sure enough I couldn't connect again. This time the eror dialog told me to recycle the device. It then worked when I retried to connect from the NXT-G window.

It seems that whenever I restart NXT-G, my first attempt to connect from the NXT-G comm window seems to trigger some dialogs on my PC that suggest hardware is being re-installed. I'm not sure but the connection may be timing out.

Again: so what I do now is initiate the connection from the NXT-G comm window and upon failing, recyle the nxt device and then re-scan and connect from the NXT-G comm window.

I hope this helps

At July 31, 2006 9:14 PM , Anonymous osdeboss said...

I manually upgraded my bluetooth driver connecting to Microsoft support. ALthough i had sp2 installed the driver is not automatically updated. After that i had no problem. Firmware is not upgraded but still as it came out of the box. After that search from your pc for bluetooth devices.

At August 01, 2006 4:33 AM , Anonymous phil from NC said...

I have kind of the same problem. I have a palm pilot life drive with bluetooth. The NXT will connect but always says line is busy every time. I have no idea what could be the problem. Phil

At August 25, 2006 10:23 AM , Anonymous Anonymous said...

Try enabeling the activesync servace on youre computer that worketd for me but now im geting "nxt lost" from the software

At September 24, 2006 5:17 PM , Anonymous Will George said...

I have the same issues. Three different PC's and My Life Drive Palm. By the way, anybody notice if your Bluetooth is 'OFF' you get the same thing. I have no real problems using the NXT-G program to connect to the brick. Sometimes it gets 'fussy' but I can live with that.

Then I downloaded the Microsoft Robotics Studio.. Life got really bad after that!

In there it said 'Then configure your PC's Bluetooth adapter to be able to communicate with the NXT. Typically this involves using the Bluetooth software to create a secure partnership connection between your PC and the device. Follow the instructions provided for your computer (if already configured with Bluetooth) or your Bluetooth adapter. During this process (if successful) you will establish an inbound and an outbound port for serial communication (COM). You will need to use these numbers in the configuration file for the tutorial applications.' Gee, all downhill from there.

In my 'humble opinion' The real problem is in the 'brick!'.. But then again what do I know?

I have three three (yes three NXT Mindstorm kits). One for me and the other two were for my grand children. All three bricks do about the same thing on five different PC's. All run XP. Three XP-Home, 1 XP-Pro, 1 XP-Media?.

All of the PC's can connect to the NXT brick (with a few hickups) but in general work OK. NONE will connect if the brick trys to connect to the PC. I'm not sure what Bluetooth stack is used on three of the computers (I did not bother to look) I figgure, if the NXT-G software can connect I should be able to go the other way. BIG mistake in my thinking.

I have tried MANY different thing and all results are about the same.

My laptop is a ACER (I like it ALOT) with internal Bluetooth (you can switch bluetooth/Net off/on at will). To be honest, the other computers used my two bluetooth dongles. One is a Microsoft the other is a D-LINK DBT-120 as suggested by LEGGO.

The ACER has a built-in Broadcom bluetooth usind the WIDCOMM stack. NXT software said it 'woulden't work' during the NXT software install. (Or something like those words. I forget exactally).. It worked anyway using the NXT-G? You know, the Mindstorms program.

I have images of all my software on my laptop so I trashed it and did a secure wipe of the hard drive. Installed a fresh XP-Home install and did ALL the updates. Geeee... Took forever!

I would assume it was using the Microsoft bluetooth stack then. I'm never SURE about these PC's!

I used the Microsoft dongle and away with the NXT software install. No other programs were loaded onto the PC. Well, except what the XP software did. I took ALOT of notes...

Then I installed the DBT-120 which is stated to use WIDCOMM stack. Even on the D-LINK download page! WRONG!!!. From the Mfg. CD and the download package from D-LINK it loaded a Toshiba stack (I think Toshiba knows what they are doing so I am NOT knocking them).

I guess in general what i'm ranting about is that with all of the PC's and whatever stack they were using the LEGO software worked OK in general and the BRICK WILL not connect to any of them. Me thinks it's the BRICK!

I do not know how to fix it but one thing I did notice on three of the PC's (I forget which ones outside of my laptop) is when setting up for discovery of the 'NXT bricks' all would go well UNTILL after it was finished. The PC software thought all was well.. UNTILL you try to connect from the brick to the PC.

Trying different things, I found one very strange thing in the Bluetooth setup dialogs. After everything went as the dialogs wanted and the brick had the PC names and all that stuff.. Try to connect... LINE IS BUSY.. As usuall! I would return to the bluetooth software Add Device Wizard. It would do it's search thing and show the Brick Name.. WITH GET THIS.. Already connected under the brick name.. PC thought it was already connected BUT NO *<> on the brick.. Just a *<.

I had noticed that sometimes just before the brick displayed ..LINE IS BUSY.. the PC's dialog would 'FLASH' connected? under the brick name and go away as if the PC tried to connect but then remembered it was already connected.

Not sure how to explain this.. Make any sence? sense? cents?

Well, all in all, I have receipts for 850 or so US dollars (including TAX) and I may be off to LEGOLAND in Europe and knock on some doors for my refund!

Not really.. It's just that..


And I had all these dreams of playing with our Lego Robo whatever's over the internet. If I could get the dang brick to connect maybe I could try messin' with the software to do it!

Have a good day all!

At September 24, 2006 6:19 PM , Anonymous Will George said...

I forgot to say in my post that I tried this with 'brick' firmware? 1.0 and 1.3? the same things happened.. SOrry

At November 24, 2006 3:28 AM , Anonymous Eric D. Burdo said...

I have been having similar troubles. I started a post outlining them here:


I'll keep it updated as I go.

At March 17, 2007 10:21 AM , Anonymous Anonymous said...

some one said that you have to disable any other connections to stop the nxt saying "Line is busy" it doesnt work please some one help!

At May 21, 2007 8:12 PM , Blogger Bob said...

Bluetooth Connection Issue / Problem : PC to NXT Brick

Technical Detail :
Lego Mindstorm Software (LMS) v1.00
LMS PC Driver v1.00 & v1.02 (from Lego website)
NXT Brick Firmware 1.04 (from Lego website)

Bluetooth Stack :
MS XP-SP2 Default, no updates/patches.

Bluetooth Hardware :
MSI BToes 2.0 3X v587-CI (Cambridge Silicon Radio - CSR chipset)

Symptoms :
LMS successfully SCAN and detects NXT brick. But unable to CONNECT to device.

TroubleShoot step :
XP Unable to create SPP/Bluetooth Serial Port.

1. Control Panel > Bluetooth devices
2. Add NXT device with NXT brick passkey (default 1234)
3. COM Port Tab > Add > Outgoing > Device = NXT > Service = Serial Port (SPP) 'Dev B'
4. Popup shows "Access is Denied".

Solution :
Change Bluetooth Service Log On Credentials.

1. Control Panel > Admin Tools > Services.

2. Bluetooth Support Service > Properties.

3. Log On tab > [Warning : Copy the "This account" field value and keep it somewhere safe. The password should be your local admin account password].

4. Check Log on as : "Local System Account" (instead of Local Service) > PopUp > OK.

5. General Tab > Service Status : STOP then START.

6. Repeat Troubleshoot steps. No more "Access is denied" popup message.

7. Test with LMS interface. If unsure, remove any existing bluetooth brick in LMS list. Scan
and then try Connecting.

I noticed the response in LMS is faster than using the Widcomm Bluetooth stack (v5.0.1.802). (By way of forcing the 'Generic Bluetooth Device' to the 'CSR Bluetooth Device' drivers in Device Manager panel)

Disclaimer :
Procees with caution. I bear no liability in case of any loss.

Bob D (Malaysia)

At September 20, 2007 5:38 PM , Anonymous Anonymous said...

We, too, suffered from very frustrating Bluetooth troubles. I use a cheap Bluetooth USB dongle, using Windows XP drivers (on a desktop) and Vista drivers (on a Laptop). On both computers, when 'scanning' from the Mindstorms software, the NXT would come up 'available'. Then, when trying to connect, a window popped up requesting the passcode (at the PC), then NXT would beep and request a passcode as well. After pressing the orange button, an error would occur in the Mindstorms software ("Error: a connection could not be made" or something vague like that). Because the error only came up at such a late stage in the connection process, I suspected that the Bluetooth hardware would be OK, but somehow a higher software layer caused the problem. After a lot of experimenting, I found a procedure that creates a Bluetooth connection, which works both on the Desktop (XP-SP2) and the Laptop (Vista). Some steps may not be needed, or alternative sequences might work, but this does it for me:

1. Switch on the PC

2. Slide in the Bluetooth dongle (my PC doesn't boot with the dongle installed)

3. On the PC, open the Bluetooth Devices window

4. If any NXT device is listed in the Devices list, Remove it (otherwise, a 'Line Busy' error will pop up later). Make sure 'Turn discovery on' is selected. Close the Bluetooth Devices window.

5. Switch on the NXT, and select 'Search' from the bluetooth menu, then 'Connect' to the found computer. Accept the passcode.

6. On the PC, a window comes up mentioning that a Bluetooth device is requesting to connect, asking if you want to allow connection. Click on the message to allow connection. A new window pops up, asking for the passcode. Type in the passcode and click Next. Again, the NXT beeps to verify the passcode; press the orange button on NXT to accept.

7. Open the Bluetooth Devices window. Select the NXT device and press 'Properties'. In the new window that opens, click the 'Services' tab. Now, Windows starts searching for services that NXT supports. Select all available services (in my case, two serial ports) and press OK. Windows now installs some new drivers. After that, close the Bluetooth Devices window.

8. Now, start the Mindstorms software on the PC, and open the NXT window. Scan for NXT devices, and after finding NXT, click "Connect" (if not already connected during scanning).

9. YES! It works! (for me anyway).

My guess is that with the above procedure, Windows not only recognizes NXT, but also knows with what type of connection services to approach NXT. Apparently, this allows the Mindstorms software to actually create a connection. Unfortunately, the sequence is a bit complicated, which is a problem for my son, the biggest Mindstorms user. Any help in shortening the sequence is appreciated.

I hope this is of any help to other frustrated NXT owners having Bluetooth problems!

At November 06, 2007 9:03 PM , Anonymous Anonymous said...

this works for the nxt software, but i am currently trying to run microsoft robotics studio, it still gives the line busy message.

At December 25, 2007 7:29 PM , Anonymous Anonymous said...

I had the same problem, I found out that in order to make the connection work correctly, NXT-G needs 3 com ports: 2 outoing ports called NXT 'Dev B' and NXT 'Dev A', and an incoming port called 'NXT'. Somehow, two of them disappeared and my system stopped working. After changing the log on for the BT service as described earlier, it seemed like Windows reinitialized that connection and correctly re-created the 3 ports and from now on BT seems to work flawlessly. I don't know the exact mechanics of the BT stack and what NXT-G expects to have in terms of port, but I just thought it could be a good hint on why it doesn't work in some cases.


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