Arduino Nano + HC-05 AT not working

Question

I have arduino nano + HC-05 bluetooth module.

I have used following pins D9, D10, D11 for HC-05 KEY, TX, RX and this works for data communication without any problems.

D9 pin is set to output pin HIGH (5v).

However, I want to be able to run AT commands to change default bluetooth configuration, for example to change a name.

I followed this tutorial for example just to make sure that I'm doing everything right but I wasn't able to run any of these commands.

I tried to use different speeds but without luck.

I also tried to connect KEY pin when VCC is disconnected (I read on some forum that this will change speed for programming to 38400) but same thing, nothing changed.

Any idea what else I can try?

But for some reason, this is what I'm getting as response from the code from that tutorial:

Starting config

Done!

Answer 1

The baud rate will change to 38400 due to this portion of the code ran upon startup:

// If you haven't configured your device before use this' '#define BLUETOOTH_SPEED 38400 //This is the default baudrate that HC-05 uses' '// If you are modifying your existing configuration, use this:' '// #define BLUETOOTH_SPEED 57600

Have you made sure your Bluetooth and serial baud rates are matching? What is the output of your setup() method from Step 2 of the instructions?

Answer 2

solder 34 pin of bt with pin wire, then connected to arduino pin9. in void setup inside arduino program, put pin 9 to low, and then some delay about 1 second, then put it high.. this way will let the bt to be in AT command. by the way, the default baud rate of bt is 38400, and software serial of bt inside arduino must be same