Blue Tooth interference and Question Re. Secondary sending

[tabbycatrobots]

I plan to take my robots, that use BT to an AFOL convention. If I am near another NXT MOC using BT, will interference be a
problem? If so, how far apart should we plan to setup our MOCs - 30 feet, 50 feet? Will BT signals from persons using BT ear
phones with their cell phones, be a problem? I am also trying to use sending from the 3 secondary NXTs to the primary. Until
now, I have only sent messages from the primary to the secondaries. Reading the manual, it sounds like the secondary, when
sending, only puts the message in an outgoing queue and the primary actually retrieves it. How does the primary know when
to retrieve from a particular secondary? Or does it simply use a round-robin method to periodically try to retrieve from all queues
on all connected secondaries? Thanks for any help.

[mightor]

Just make sure you have everything paired before you to the convention. It's not fun to try and wade through a few hundred BT devices to find the one you need.

As for the second part your question, I am not sure, I try to not use BT when I can.

- Xander

[hassenplug]

1) What AFOL event are you going to?

2) Just to clarify Xander's comment, Bluetooth is designed to work together in the same room, without interfering. So, you should not have problems, as long as you have paired them, in advance.

3) The master constantly polls the slaves to see if they have any messages. (so, yes, round robin polling)

[dimasterooo]

I'm not sure what language you're programming in, but in RobotC you can pair up with a specific NXT at the beginning of your program, so you don't have to do it manually.

For the slave (or whichever one you turn on first):

Code: Select all

setBluetoothOn();

For the master (or whichever you turn on second):

Code: Select all

setBluetoothOn();
btConnect(1, "Alfred");

So you'd just change "Alfred" to whatever your first NXT is called and it should do the trick (it works for me). That way you wouldn't have to pair them in advance, and you won't have to do anything manually at all.

[tabbycatrobots]

Thank you for the ideas; these will help. I'm using NXC.
I'm planning on going to Brickfair in Virginia. I'm "teaching" my robots to dance. I feel like I'm teaching a group
of 3 year olds, and they soon get out of sync. I'm trying to add some BT code to the dance routine to try to
keep them in sync. I'm thinking that using BT to sync the dancers may be easier than trying to match 2 motors
on each of 4 dancers as they travel in forward and reverse, and do twirls. Also, using BT, I can load multiple
dance programs on each robot, and the leader can send a message to the other 3 as to which routine to do next.
I'm sure I'll learn a lot over the next several weeks, not sure about my dancers.
Regarding BT connecting under program control, I've used that in other projects with success. It does
take several seconds to make each connection, but does seem reliable, at least at home where I know of no
interference.