HC-05 sending inappropriate data

Hello everyone.
I've been trying to interface an HC-05 to Arduino UNO for the last 2 days.
I connected the pins as follows:

RX --> TX
TX --> RX
5V --> 5V
GND --> GND

I used a simple program to output data using serial monitor sent over by an android app.
I've used 2 most popular Android Bluetooth apps but on clicking buttons on the app, my serial monitor displays '◰' and 'x'.
So clicking each different button outputs either '◰' or '◰x'.
I'm a beginner in this hobby so any help will be highly appreciated.

GA11:
Hello everyone.
I've been trying to interface an HC-05 to Arduino UNO for the last 2 days.
I connected the pins as follows:

RX --> TX
TX --> RX
5V --> 5V
GND --> GND

I used a simple program to output data using serial monitor sent over by an android app.
I've used 2 most popular Android Bluetooth apps but on clicking buttons on the app, my serial monitor displays '◰' and 'x'.
So clicking each different button outputs either '◰' or '◰x'.
I'm a beginner in this hobby so any help will be highly appreciated.

Google Martyn Currey HC-05 for the best tutorial

Bluetooth is merely a radio relay. The only way it can "send the wrong data" is when you feed it the wrong data to send, or improperly read data from it, in which in both cases it is still innocent, and you are to blame.

Your code is apparently a secret, but it may be due to serial input, and nothing to do with bluetooth,
Try here http://forum.arduino.cc/index.php?topic=396450.0

It may also be down to mis-matched baud rate. If you haven't re-configured HC-05, use 9600.

Please check your HC05 Bluetooth setup against the working setup of this link.

Nick_Pyner:
Bluetooth is merely a radio relay. The only way it can "send the wrong data" is when you feed it the wrong data to send, or improperly read data from it, in which in both cases it is still innocent, and you are to blame.

Your code is apparently a secret, but it may be due to serial input, and nothing to do with bluetooth,
Try here http://forum.arduino.cc/index.php?topic=396450.0

It may also be down to mis-matched baud rate. If you haven't re-configured HC-05, use 9600.

Thank You :slight_smile:
It was due to baud rate mis-match.

I connected the pins as follows:

RX --> TX
TX --> RX
5V --> 5V
GND --> GND

In spite of clear specification that RX-pin of HC05 is not 5V Logic tolerant, do you still prefer to remain with the above connection instead of feeding the UNO's TX-signal via a 2.2k + 4.7K resistor network? ((5/6.9)*2.2 = 3.4V)

GolamMostafa:
In spite of clear specification that RX-pin of HC05 is not 5V Logic tolerant, do you still prefer to remain with the above connection instead of feeding the UNO's TX-signal via a 2.2k + 4.7K resistor network? ((5/6.9)*2.2 = 3.4V)

Oh, I forgot to mention.
I'm using 1k+2k resistors for HC05's RX connection to UNO's TX.