Arduino Mega 2560 PRO Mini cannot receive data thru HC-05

Hello, i have been days debugging my problem in receiving data in my arduino mega 2560 pro mini, but the TX is working. transferring data from my mega to android is working.

what i have done :
-Check the connection if the connections are connected using multitester
-Check the other Serial pins ( 18, 19) and so on.
-Changing Some baud rates, ( but my default is 9600)
-Change the Arduino Mega 2560 Pro Mini ( i have 2 pcs )
-Changing the wires, ( seems connected since i tested it with multitester )
-Test the current code, current connection with my arduino nano

i have my arduino nano, same code, same blueooth module, same connection with the rx , tx pins. it works.

when i try to change my main board with arduino mega 2560 pro. rx,tx pins seems not working. im using the hardware RX,TX pins.

anyone have the same scenario here?

Arduino IDE : 2.2.1
Board: Arduino Mega 2560 Pro Mini

anyhelp will much be appreciated.

Please take a look at the "How to get the best out of this forum" post, and follow the directions to post your code, using code tags, and a wiring diagram.

On the Mega, you should be using hardware Serial1, 2 or 3 for the HC-05, not the serial port used for program upload, and don't forget to use logic level shifters, required any time you connect a 5V MCU to a 3.3V device.

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i see, but i tried the serial1, serial2, serial3 of the pins and also not working, hmm.
the same hc-05, same wire connectors and same code works for the arduino nano, is there any need to update for the pinout to work? i think pinouts are the one not working here,

Are you using the required logic level shifters? Post a wiring diagram.

no i dont have, just connecting vcc, gnd to mega 5v and gnd,
rx of hc-05 to tx of mega.
tx of hc-05 to rx of mega.

That is a serious problem. The RX input and TX output of the HC-05 are 3.3V ONLY, so you may already have damaged the Arduino, the HC-05 or both.

The minimal required logic level shifter is a voltage divider from Arduino TX to HC-05 RX, as described in this tutorial.

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