How to Connect Your LEGO Mindstorms NXT to Bluetooth

Connecting your LEGO Mindstorms NXT to Bluetooth allows for wireless communication, enabling you to program, control, and even link multiple NXT bricks together for more complex robotic projects. The NXT brick comes with built-in Bluetooth capabilities, making this a straightforward process.

Understanding NXT Bluetooth Connections

The LEGO Mindstorms NXT can establish Bluetooth connections in two primary ways:

NXT to Computer: This is typically used for downloading programs created in software like LEGO Mindstorms NXT-G, LabVIEW, or other third-party programming environments, and for controlling the NXT remotely from your computer.
NXT to NXT: This allows two or more NXT bricks to communicate directly with each other, sharing data and coordinating actions without needing a computer in between.

Connecting Your NXT to a Computer via Bluetooth

To connect your LEGO Mindstorms NXT to your computer, you'll need to enable Bluetooth on both devices and then pair them.

Step-by-Step Guide for NXT to Computer Connection:

Prepare Your NXT Brick:
- Power On: Turn on your NXT brick.
- Navigate to Bluetooth Settings: Using the orange arrow buttons, scroll to the "Bluetooth" menu option and press the orange enter button.
- Turn Bluetooth On: Select "Bluetooth" again and ensure it is set to "On."
- Set Visibility: Go back to the Bluetooth menu, select "Visibility," and set it to "On." This allows your computer to discover your NXT.
- Optional: Change Name: If desired, you can change your NXT's name in the Bluetooth menu under "NXT Name." This helps in identifying it when multiple NXTs are in range.
Pair with Your Computer:
- Enable Bluetooth on PC/Mac: Ensure your computer's Bluetooth is turned on.
- Search for Devices: On Windows, go to "Settings" > "Devices" > "Bluetooth & other devices" and click "Add Bluetooth or other device." On macOS, go to "System Preferences" > "Bluetooth."
- Select Your NXT: Your computer should discover your NXT (e.g., named "NXT" or your custom name). Select it.
- Enter Passkey: Both your computer and the NXT will prompt you for a passkey. The default passkey for the LEGO Mindstorms NXT is usually 1234. Enter this on both devices.
- Confirm Connection: Once the passkey is entered and confirmed, your NXT and computer should be paired.
Connect Using Programming Software:
- Open Software: Launch your preferred programming environment (e.g., LEGO Mindstorms NXT-G Software).
- Establish Connection: Within the software, look for a "Connect" or "Bluetooth" option. It should now list your paired NXT brick. Select it to establish the connection. You can then download programs or control your NXT wirelessly.

Connecting Two NXT Bricks (NXT to NXT) via Bluetooth

Connecting two NXT bricks allows them to send messages and data to each other, enabling advanced collaborative projects. For example, you could have one NXT act as a master controller for another.

Step-by-Step Guide for NXT to NXT Connection:

Imagine you have two NXT bricks. Let's call them "NXT" and "Mickey." You want them to communicate.

Prepare Both NXT Bricks:
- Power On and Bluetooth On: Ensure both NXT bricks are powered on and their Bluetooth is set to "On" and "Visibility" is "On" (as described in step 1 above).
- Set Unique Names: It's helpful to give each NXT a distinct name (e.g., "NXT" and "Mickey") for easier identification during the pairing process.
Initiate Search on One NXT:
- Go to Bluetooth Menu: On one of the NXTs (let's say "NXT"), navigate to the "Bluetooth" menu.
- Select "Search": Choose the "Search" option. The NXT will begin looking for other visible Bluetooth devices.
- Select the Other NXT: When it finds the second NXT (e.g., "Mickey"), select it from the list.
Pair and Confirm:
- Enter Passkey: Both NXT bricks will prompt you to enter a passkey. Enter 1234 (or your chosen passkey) on both bricks and confirm.
- Connection Established: Once confirmed, the two NXT bricks will be paired. You can usually see the paired brick listed under "Connections" in the Bluetooth menu.
Program Communication:
- To make the NXTs actually communicate, you'll need to write programs that use the "Bluetooth Send" and "Bluetooth Receive" blocks (or equivalent functions in other programming languages). These blocks allow the bricks to exchange messages, sensor data, or motor commands.

Troubleshooting Common Bluetooth Issues

Issue	Possible Cause	Solution
NXT not found by computer	Bluetooth off on NXT/PC; NXT not visible.	Ensure Bluetooth is "On" and "Visibility" is "On" on the NXT. Check PC's Bluetooth. Restart both devices.
Pairing fails (incorrect passkey)	Entered wrong passkey; default changed.	The default passkey is `1234`. Re-enter carefully. If still failing, try restarting both devices.
Connection drops intermittently	Interference; low battery; out of range.	Reduce distance between devices. Ensure NXT battery is charged. Minimize other Bluetooth/Wi-Fi devices nearby.
Programming software can't connect	NXT not paired with PC; software not updated.	Ensure NXT is successfully paired with your computer first. Update your NXT-G or other programming software to the latest version.
NXT-to-NXT connection fails	Only one NXT searching; visibility off on one.	Ensure both NXTs have Bluetooth "On" and "Visibility" "On." Initiate search on one NXT and select the other when found.

Tips for a Smooth Bluetooth Experience

Keep Charged: Ensure your NXT's batteries are adequately charged for stable Bluetooth performance.
Stay in Range: Bluetooth has a limited range (typically around 10 meters or 30 feet). Keep your devices relatively close for a reliable connection.
Avoid Interference: Large metal objects, Wi-Fi routers, and other Bluetooth devices can sometimes cause interference. Try to operate your NXT in an open area.
One-Time Pairing: Once paired, your NXT and computer/other NXT should remember each other, making future connections quicker.

By following these steps, you can effectively utilize the Bluetooth capabilities of your LEGO Mindstorms NXT to expand your robotic creations.