Pairing via Bluetooth

Detailed instructions on how to pair the ChapR to your NXT brick via Bluetooth.


Reboot the NXT.

Whenever you’re working with Bluetooth on the NXT, it is wise to reboot first. Sometimes the NXT just likes to be rebooted…really.  When you reboot, you will see the normal menu on the NXT that looks something like this:

This NXT is named “NXT – A”.  Your NXT will probably be named something different.  If you are competing on an FTC team, this is probably going to be your team number like “6710”.  But the NXT name doesn’t matter to the ChapR.


NXT Bluetooth indicatorMake sure Bluetooth is on.

The NXT Bluetooth can be turned on or off. Sometimes it will mysteriously turn off, so to pair with the ChapR you need to make sure that is is on. The indicator for Bluetooth is in the upper left of the NXT screen.

Bluetooth ON


Bluetooth OFF (bad)



If Bluetooth is on, then skip to step 3.

If Bluetooth is off, you turn it on by going to the “Bluetooth Menu” on the NXT – makes sense doesn’t it? You get to the Bluetooth Menu from the main menu (as seen on right) by pressing the RIGHT ARROW on the NXT 3 times, the press the center ORANGE button once.  When you enter the Bluetooth menu with Bluetooth off, the only thing you can do is turn ON the Bluetooth.  So press the ORANGE button on the NXT 2 times to turn on Bluetooth.


Turn on the ChapR in “pairing mode”.pairing-via-bluetooth

Now that the NXT is ready, go grab your ChapR and power it on in its “pairing mode.” Press both buttons on the ChapR until both LEDs start to flash (about 3 seconds).  The two flashing LEDs tell you that the ChapR is in Bluetooth pairing mode.

In Bluetooth pairing mode the ChapR can be “seen” by other Bluetooth devices, and can respond to connection requests.


Connect to the ChapR from the NXT.BT-menu

In this step you will be using the NXT to connect to the ChapR over Bluetooth.  To do this, go to the Bluetooth menu on the NXT (see step 2 if you don’t know how to do this). When Bluetooth is off, the Bluetooth menu looks like this.

From this menu, press the ◀ (left arrow) on the NXT once, then press the ORANGE button to start the NXT search.


Now the NXT will start searching for all Bluetooth devices in its local area.  Due to step 3, the ChapR is one of those devices! Note that if you don’t put the ChapR in pairing mode, the NXT won’t be able to find the ChapR in a search. This is done on purpose so that your ChapR can’t accidentally be paired to another NXT while you are using it for drive practice.


During the search, you may see multiple devices pop-up on the NXT screen.  But have patience and wait for it to do its complete
You will then have to use the ◀ (left arrow) and ▶ (right arrow)  to find your ChapR in the list.  Once you find YOUR ChapR, press the ORANGE button.  In this case, it is “ChapR-7”.



NOTE – If you are at a competition, there may be MANY Bluetooth devices that your NXT finds during its search.  In fact, there can be so many that the search seems that it may never complete. And when/if it does, you can’t find your ChapR anywhere.  In these situations it is very smart to use the USB Pairing method.  But for these instructions, we’ll assume you can find your ChapR.

BT-connectThe NXT will then give you the opportunity to CONNECT to your ChapR. Press the ORANGE button again to confirm that you want to connect.





And one more question!  The NXT will prompt to to select the slot for which the connection should be made.  You can select any of the slots and it will work the same way.  So just press the ORANGE button.




NBT-connectingow the NXT and ChapR will have a quick chat to finalize the connection.  During this chat the NXT will display the “Connecting…” screen.




BT-passkeyIf this is the first time you have paired this NXT and the ChapR, the NXT will ask you to enter a passkey.  Just press the ORANGE button to accept the default of “1234”.




At this point, when the ChapR and the NXT finally connect you will hear the special connection noise from the NXT and a reassuring “squeep” from the ChapR.  The ChapR Connect LED will also be continuously lit (not flashing).

v0.3 Case (6)



Verify that Bluetooth is connected.BT-verify-connected

There is a very small little indicator that Bluetooth is connected.  Right next to the Bluetooth on indicator is a little diamond.  This indicates that Bluetooth is connected.  Otherwise it is just a < (less-than sign).   PHEW! It’s a lot of work to get Bluetooth paired to the ChapR.  Fortunately, you only have to do it once.  Or more accurately, you only have to do it whenever you want to use the ChapR with a different NXT.

The ChapR will always remember the last NXT that it paired with, and will connect to it in seconds when you power it on in the normal mode.

But you really should check out the USB Pairing procedure for the ChapR.  It is really easy and fast…
but you do have to have a USB cable with you!