hello I have a problem with the hc05 module. After connecting it to arduino when I try to send messages from an app on my phone, the arduino seems to receive them but not correct, that is, it only receives: ?? x? x etc. I do not understand why, I am using an arduino menga the pins tx and rx are 10 and 11, the only thing I have not decreased the voltage of the pins from 5 to 3.3 times but I don't think this is the problem
Have you set the correct bit rate in the code you didn't post?
Yes I used 38400
In AT Command Mode, the default Bd = 38400; in Data Mode, the default Bd = 9600. So, try with Bd = 9600 in your sketch.
1 Like
(and post the code...)
thanks i solved i set the serial to 9600 and i put a voltage partitioner on the tx to bring it to 3.3 volts
It is the RX-pin (and not the TX-pin) of HC-05 which needs around 3.3V voltage through a divider circuit (Fig-1).
@hydas, your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advise on) your project 
See About the Installation & Troubleshooting category.
If your problem is solved, you can click the solution checkbox under the most useful reply to let others that are experiencing the same problem know.
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.