Ubox integrated bluetooth trouble shooting guide

• General introduction
• Internal electronicprinciples
• Correct operation steps
• Normal problems and solutions

Ubox integrates the NRF51822 Bluetooth module, which is compatible with vedder b/nrf51_vesc firmware. Users can assign Bluetooth module connected to ESCA or ESCB, It’s convinient for user to connect it with mobile vesc tool app . However, the Bluetooth module uses the UART port to communicate with ESC, and the built-in 2.4G receiver of Ubox can also use UART for communication with ESC, so it has caused some confusion for users and is prone to issue. The purpose of this blog is to explain the internal circuit principle and the solutions of common issues.

2. Internal Eelectronic principles

2.1Ubox internal connections of UART diagram

2.2LED lights indictions of bluetooth module

 Confirm which way you choose to set the bluetooth

(1) if you’re using ubox with remote Uni1

            Menu->Ports Config->Bluetooth ：

            BT IDLE

           BT TO ESCA, if ESCA's UART is not occupied by 2.4G receiver;

            BT TO ESCB, if ESCB's UART is not occupied by 2.4G receiver;

If you’re not familar with remote Uni1 operation,please go to our product page to get user manual or product page operation video 

(2) If you don’t have uni1 remote，3 seconds after power on Ubox ,

BT TO ESCA, click power button 3 times then wait 2seconds.

BT TO ESCB, click power button 4 times then wait 2seconds.

BT IDLE,    click power button 5 times then wait 2seconds.

Note: 

• The bluetooth module can’t be connected to two ESC at the same time.
• Ubox's built-in 2.4G receiver and Bluetooth module cannot be connected to the ESC on the same side at the same time. Because Ubox's IO is compatible with VESC 75/300 (R1), not VESC 75/300 R2. Compared with R1, R1 does not have an extra UART to connect to the NRF module. R1 and R2 also have different IO allocations.
•  The UART of the ESC is connected to the external port at the same time, so when using the built-in Bluetooth module, the UART TX/RX of the external port cannot be occupied. 

• The two ESCs inside Ubox transfer data through the internal canbus interconnection, and the transmission rate of the canbus is relatively low. When the transmission data is relatively large, it is easy to cause congestion.

 3.3  If the Bluetooth module in the controller and the Bluetooth function of the mobile phone are working normally, VESC BLE UART [XX:XX:XX:XX:XX:XX] will appear, indicating that the mobile phone has found the VESC Bluetooth device. Then click the CONNECT button.

After successfully connected, the RT DATA page will display the correct voltage, temperature, current and other information.

3.4 Notes

• BT connection doesn’t have to PAIR with the VESC tool moble APP. PAIR means this BT(once paired) will not connected to another VESC tool moble APP(usually another phone).
• If you’re building 4WD board, you can use two UBOX’s bluetooth. Just switch to read data in app.

4. Normal problems and solutions

4.1 normal problems

This fault is usually that the Bluetooth UART is not correctly connected to the ESC. Please refer to the description in 2.3 to check the Bluetooth connection configuration. 

If fault still exists after above check, you can try to assign the Bluetooth connection to the ESC on the other side. If the connection to the ESC on the other side is successful,  the failed side may be the hardware circuit fails, or the UART pin of the external port is something wrong.

4.2 Scan nothing 

In this case, the canbus between the ESCs on both sides is not connected. Firstly please check the canbus indicator of the controller.

If LED7 does not light up, the canbus switch inside the controller is not turned on, the way to turn it on:

Option 1, with remote Uni1

        Menu->Ports Config->Can bus, set to ON.

       Option2, without remote Un1,3 seconds after power on Ubox：

CANBUS switch on，click power button 6 times then wait 2seconds.
CANBUS switch off，click power button 7 times then wait 2seconds.

4.3 When using Uni1 remote control and Bluetooth connection at the same time, the Bluetooth connection is easy to disconnect

The reason for this phenomenon is that both Bluetooth and Uni use the same 2.4GHz frequency band, and the internal 2.4G receiver will continuously return data to the remote control. This means that the 2.4G receiver will transmit signals outwards. The Bluetooth module is very close to it, so this transmitted signal will affect the reception of the Bluetooth module.

4.4 We'll continue to collect more market feedback problems. 

5. Lastly, if you want to use the bluetooth stably, you can try to use the external receiver to control the ESC