You can use the NXT with either AA batteries or the NXT Rechargeable
(Optional: Alternate Steering Lever)
You can use either the steering wheel or the steering lever, or another
dial or lever of your own design.
Remote Control Programming
The SteerRemote program for the remote control
provides one general purpose way to send Bluetooth messages from the
remote control to another NXT (other strategies are possible). A
receiving program on the other NXT must be used to interpret the
Bluetooth messages and take action. For example, see the
SteerBTCar program from the Race
Car project. Instructions to use the remote with the Race Car
The SteerRemote program sends three different
kinds of Bluetooth messages to three different mailboxes on the receiving
The first message, sent to mailbox 1, is a Number that
indicates the angle in degrees of the steering wheel control (positive
or negative). This message is sent continuously about 20 times per
second, whether or not the steering control changes position.
The second message, sent to mailbox 2, is a Number that
indicates when an NXT button is bumped (pressed and then released) as
follows: 1 = Left Arrow button, 2 = Enter button, 3 = Right Arrow
button. These messages are only sent when an NXT button is bumped
and are only sent once for each bump.
The third message, sent to mailbox 3, is a Logic message
that indicates whether or not the touch sensor is pressed (True if
pressed). This message is sent continuously about 20 times per
second, whether or not the touch sensor changes position.
Bluetooth Wireless Remote Control with Two NXTs
You will need
another NXT to receive the messages from the remote control and
an appropriate receiving program for that NXT project. The
following example instructions show how to set up an connection
between the Steering Remote Control and the
Race Car project.
program to the Race Car NXT, but don't run it yet.
program to the Steering Remote Control, but don't run it yet.
Bluetooth connection from the remote control to the Race Car. See your NXT User Guide for
instructions, summarized here:
Bluetooth is turned on for both NXTs from the Bluetooth
menu (from NXT main menu)
NXT for the remote control, go to the Bluetooth
menu, and if this is the first time these two NXTs have
been connected, pick Search. Pick Contacts if they
have connected before.
name of the NXT for the Race Car from the list
using connection number 1
for a Passkey, you can accept the default 1234 key on
are connected when they both display a diamond after the
Bluetooth icon in the upper left corner of the screen.
program on the remote control NXT.
program on the Race Car NXT.
The Race Car will operate
from the remote control as follows:
steering wheel will steer the front wheels. The
Race Car's steering motor can only steer 75 degrees in
either direction (which results in less than 75 degrees
of steering angle because of the gears), so the
receiving program will limit the steering angle to this
range and ignore extra turning of the steering wheel.
release the Left Arrow button to decrease the drive
power (speed) by 20%, and the Right Arrow button to
increase speed by 20%. The current power level is
displayed on the Race Car NXT (not the remote NXT).
release the Enter button to toggle Reverse mode (once to
shift into Reverse and again to go back to forward).
When in Reverse mode, the car will drive and turn in
Note that you could
use the Steering Remote Control to control another NXT project that can
respond in any way it wants to the Bluetooth messages described
in the Programming section above, so you
could assign other actions to the wheel/lever and the four available buttons if you
Pick another robot
vehicle to control with the Steering Remote Control or design your
own, and write a Bluetooth
receiving control program for it to use.
Try modifying the
SteerRemote program to make the remote control work better
or differently for your own robot designs. For example, you
might want to change the NXT button behavior from "bumped" to "press
and hold", or perhaps add some feedback on the display.
Can you use or modify the
Steering Remote Control to control something that is not a vehicle?
2007-2011 by Dave Parker. All rights reserved.
All project designs, images, and programs are protected by copyright. Please see
the usage policy.