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Subject: 
Re: NXT to NXT communication?
Newsgroups: 
lugnet.robotics
Date: 
Thu, 4 May 2006 02:55:36 GMT
Viewed: 
3090 times
  
In lugnet.robotics, Steve Hassenplug wrote:
In lugnet.robotics, Joe Strout wrote:
In lugnet.robotics, Steve Hassenplug wrote:

The NXT to NXT communication works very well, and is easy to use.  Here's some
video of an NXT controller for an NXT robot...

http://www.brickshelf.com/gallery/Hassenplug/Robots/NXT/nxtremotecontrol.wmv

Neat!  You used the NXT motors as inputs on the remote control?  How stiff are
they when you do that?


The motors offer little resistance when used this way.  However, there's
something else which I think is kind of cool.  If you look close, when I let go
of the controller, the paddles return to the middle, and the car stops.  Using
just one block at the start of the program, I set the motor to "stay there" so
when you push the paddle forward, it springs back.

The steering wheel does the same.  Actually, in the latest version of my
program, when you let go of the steering wheel, the car's wheels straighten out.
The more you turn it, the more the wheels turn.



Also, I noticed at one point you scooted the controller closer to the car.  Was
that because it had lost the signal?  What is the effective range, anyway?

NO.  I moved the controller so it could be seen better by the camera.  The
Bluetooth spec says it will work within 10 meters.  (If you really want to know,
the NXT is a Class 2 Bluetooth device)


I also wonder what happens when you have more than two NXT bricks in the area.
How do you sort out signals from multiple sources?

This is all done with the Bluetooth stuff.  We don't need to worry about
interference, or error checking.  I assume messages could be lost, but I've not
had a problem with that.

Once two NXTs are "paired" together, they can communicate back and forth, in a
noisy room.  At the FLL World Festival in Atlanta, I searched for Bluetooth
devices a couple times, and found MANY in range, but never had a problem with
interference.


Brian said:
First, all the incoming messages come in over one channel (connection [0]; connections [1], [2], and [3] are for outgoing messages),

This is not exactly true.  All connections are bi-directional.  You can send and
receive over each connection.

However, (almost like Brian said) Connections 1,2,&3 are outgoing connections.
That's like if this NXT originates a phone call.  And, it has one incoming
connection (connection 0).

So, when you send a message, you specify the "connection" and the "mailbox" the
message is going to.

Clear as mud?

Steve

Steve, your remote is pretty cool.

It’s a great idea if you have more than one NXT.  I checked with my purchasing
manager (my wife) and I don’t think my request for capital expenditure will be
approved for more than one NXT this year.  With that in mind, has anyone
experimented with creating a remote using a computer peripheral (such as a
gamepad/joystick/mouse connected to a Bluetooth enabled PC) ?

What Bluetooth profiles does the NXT implement?  For example one standard
profile is Human Interface Device (HID).  It’d be interesting to create a
computer interface out of LEGO for my laptop, such as a NXT mouse or keyboard.
Or something like a NXT barcode scanner that types the number on a PC via a HID
interface (there are some commercial barcode scanners that work that way).

-Tim



Message has 1 Reply:
  Re: NXT to NXT communication?
 
(...) Yes, that's a tough one... (...) I've played around with a few ideas using bluetooth. In addition to the NXT->NXT remote, I wrote a program for my Bluetooth enabled PDA using eVB. Jim Kelly actually has a screenshot in his blog (URL) under (...) (19 years ago, 4-May-06, to lugnet.robotics)

Message is in Reply To:
  Re: NXT to NXT communication?
 
(...) The motors offer little resistance when used this way. However, there's something else which I think is kind of cool. If you look close, when I let go of the controller, the paddles return to the middle, and the car stops. Using just one block (...) (19 years ago, 3-May-06, to lugnet.robotics)

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