I've got a bluetooth module from dx and connected it to my Arduino UNO R3. It was working just perfect but after a couple of hours of work it just stopped sending data.

I think, the problem is with RX,TX pins voltage. Arduino sends 5v on TX pin, but I can't figure out, which voltage does BT board receive on it's RX. I think, I've burnt this BT and don't want to do the same with the new one.

There were no docs with the board. There is a doc only for the main board(not for the breadboard), and it says, it operates with 3.3V levels of RX and TX pins. All over the net people say, that the breadboard from DX works with 5 volts too... But I've the negative experience...

Any help appreciated!


1 Answer 1


I have one of these modules here somewhere (works fine, once you find the right documentation)
IIRC it has an on board 3.3V regulator, so you can feed it 5V (range 3.6V - 6V) on the VCC line okay.
However, the TX and RX lines are 3.3V, so you must use the same level logic here. If your Arduino pins are 5V logic you need to level shift them accordingly to avoid breaking the new module.

  • \$\begingroup\$ Thanks much! Do I get it right that I just need to use a resistor between arduino's TX pin and board's RX? \$\endgroup\$
    – Kolyunya
    Commented Nov 8, 2012 at 12:47
  • \$\begingroup\$ do you have only main board or a breadboard from DX with soldered pins? Maybe the breadboard does have a resistor? \$\endgroup\$
    – Kolyunya
    Commented Nov 8, 2012 at 13:04
  • \$\begingroup\$ @Kolyunya Hi, have you managed to connect JY-MCU Bluetooth using levelshifter or you still connect it directly? \$\endgroup\$ Commented Dec 17, 2012 at 15:42

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