Problem with BT-210 and OpenCM 9.04

Hello everyone,
I am seeking for help in using a BT-210 device to connect an OpenCM 9.04 with other devices via bluetooth. My aim is to pass text strings via bluetooth to the OpenCM 9.04 as commands to control a robot I am building. The commands I am planning to use are already tested using a standard Arduino IDE serial monitor connected via USB to the Serial port of the OpenCM 9.04
However, when I try to use the BT-210 to pass text via the Serial2 port it seems that nothing goes to the board and I do not understand what I am doing wrong.

To check the BT-210 device I did the following tests (repeated several times):

First test:
For this test I used a Mac Mini (Intel processor)

  • Following BT-210 e-manual page I connected the OpenCM9.04 to the USB port of the Mac and uploaded the “c_Serial_Serial2_Converter” sketch from Arduino IDE.
  • Once completed the upload, I removed the board, connected the BT-210 and connected the board again to USB. The blue LED on the BT-210 started flashing regularly.
  • I opened the Arduino IDE Serial Monitor (on the USB port).
  • I switched on the Bluetooth connection on the Mac and paired the BT-210. The blue LED stopped flashing remaining still and the following message appeared in the Arduino Serial Monitor: “CONNECT 38f9d320bba1”.
  • I started the CoolTerm app (a terminal for Mac) and switched on the connection with the ROBOTIS_210_F8 device (enabling Local Echo as instructed). The BT-210 seemed connected (the LED stopped flashing and remained still blue), however I got no reply from it whatever command I entered in the Terminal (!, AT, ATZ, AT+BTROLE…). The same when entering text in the Arduino Serial Monitor window.

Second test:
For this test I used an android phone with bluetooth and the “Arduino bluetooth controller” app.

  • I uploaded the following sketch on the OpenCM9.04 board, with the aim to switch on/off the board LED via bluetooth

    #define BTSerial Serial2 // OpenCM9.04 Serial2 port
    #define LED_PIN 14 // OpenCM9.04 board LED
       void setup()
           pinMode(LED_PIN, OUTPUT);
       void loop()
             char command =;
             if(command == ‘a')
               digitalWrite(LED_PIN, HIGH);
             else if(command == 's')
               digitalWrite(LED_PIN, LOW);
  • After uploading the sketch, I disconnected the board from the Mac and connected it to an external 5V powerbank via USB. The board switched on and the BT-210 started flashing blue.

  • I opened the terminal app on my Android phone and paired the BT-210, whose LED stopped flashing to remain still.

  • Via the app I sent the commands foreseen in the sketch, again without any success.

  • As the app has also terminal function, I repeated the first test sending AT commands to the BT-210, never get any reply.

The BT-210 (BT-210 REV1.2) is part of a Robotis MINI package and it was fully functioning when used to control the MINI with the standard Robotis firmware and Android app (same android phone I used for the second test above).
Apparently it is still working, at least from the behaviour of the blue LED, however it does not reply to any command and does not pass anything to the Serial2 port of the OpenCM 9.04.

I also repeated the test with 2 different OpenCM 9.04 boards in the event the board’s port was failing, but nothing changed.

Should someone be able to help me solve this, I would very much appreciate!
In any case, thanks for reading.

You reported your BT-210 Firmware is of V.1.2, and the current firmware for BT-210 is V.1.3 (I think). A few years back, I had to send all my BT-210s back to ROBOTIS (USA) so that they can do this update using special hardware (that us users don’t have). Are you located in the USA?

@Tech_Support or @Yogurt_Man probably have a better idea if this is the case or not.