So, from one popular Chinese store I ordered a HC-06 module that I received... and due to some mistake from a store, I received a HC-06 without connecting pins. So usually HC-06 looks like this (with blue plate underneath where 4 pins are available to solder or connect): enter image description here

I just received the one without this blue plate and pins: enter image description here

How do I connect it to Arduino if there are no pins? Where are usual GND, TX, RX pins (is this schematics correct?)? Is it okay if I just solder a wire to some of them without this blue under-plate?

Also do I need to add some resistors or other components if I connect wires directly to these half-circle pins?

Thank you!

1 Answer 1


The small green PCB is the real HC-06 board. The blue board has 2 functions:

  1. It breaks out the contact pads of the HC-06 to the bigger pins.

  2. It has a voltage regulator on it so that you can provide it with 5V power, which then get's converted to 3.3V for the HC-06 (which is a 3.3V device).

The next steps depend on what Arduino board you have:

  • If you have a 3.3V Arduino Board, you can directly connect the pads on the HC-06 (by soldering pins or wires to them) to the corresponding Arduino pins:

    Arduino <--> HC-06
      3.3V  <--> 3.3V
      GND   <--> GND
      TX    <--> RX
      RX    <--> TX

    Also you can connect a fitting LED to the LED pin. I spontaneously cannot find data about the max current of this pin. But I guess it is in the range of 10 to 20 mA. Use a corresponding combination of an LED and a resistor.

  • If you have a 5V Arduino, you need to consider the voltage difference. On the Uno and Nano you have a 3.3V regulator on board. The regulator itself is rated for 150mA, but since it is not cooled, the limit is more like 50mA (see this forum thread). This datasheet of the HC-06 states, that it draws at max 30-40mA, so you can get away without an extra 3.3V regulator, just by connecting the both 3.3V pins on Arduino and HC-06. If the voltage regulator overheats despite being under 50mA, you need to buy an extra 3.3V voltage regulator, that can handle the current.

    Don't forget to use a voltage divider on the Arduino-TX --> HC-06 RX line to divide the Arduinos 5V down to 3.3V. This line isn't even regulated by the blue breakout board, so you would need this voltage divider either way.

    Ground connection and the LED are the same as in the first case.

So all in all you can still use the HC-06, just with a little bit less ease than with the blue breakout board.

  • So in order to use my voltage divider I have to connect 3.3V of HC-06 to the same 3.3V on my Arduino Nano board? Will it overheat then?
    – Max Krizh
    Commented Jan 31, 2020 at 12:00
  • 1
    Connecting both 3.3V pins between Arduino and HC-06 is for the power supply. My guess is, that it won't overheat. But I have to state, that it goes rather near the limit of 50mA. I wrote it the way above, to state, that I cannot be sure about it. With an extra voltage regulator, that can provide more current, you will definitely be safe. It is your decision, if you want to try it without.
    – chrisl
    Commented Jan 31, 2020 at 13:17

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