Using AT Commands to Set Up Your Bluetooth Module : HC-05 and HC-06 

Glad it was helpful!

You are welcome!

Hi. There's always a 'make it work' button that no one tells you about. Glad it helped.

Hi. That's strange. Are you running the basic terminal code to send your commands directly to the HC05? Is anything coming out of it? Have a look at the data sheet for your device to make sure you've got the right baud rate, stop and parity bit settings. If these are off it might not be able to read your commands. Good Luck!

@@BytesNBits thanks. Yes have tried everything. I'll just stick to to the hc06 as they work

Same problem and seems a common one but no one has any good answers other than replace the bluetooth module which I'm sure is not the problem.

Have you checked your serial terminal baud rate? Try a few different settings to see if the speed on the HC-05 has been set to something different. Other than that, check your wiring, try a different HC-05 and Arduino if you have one. I hope you get it working.

@@BytesNBits turns out you're supposed to short circuit two points together. Not sure how but that's how my teacher said they did it.

@@magwitch Hi. Your teacher is correct - sorry forgot the HC-05 works differently to my HC-06. There should be a small button on the HC-05 unit. You need to hold this in as you turn on the power. This will put it into AT mode so it will talk to you. Set it up as you want and then power off and on again to get it back to normal mode. I hope this works!

ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ykgt4v7_4y4.html

Serial speed is by default 38400 in AT mode and you need to connect the key pin also on HC-05.

If you've copied from the web page the top line has gotten corrupted by the editor #include <SoftwareSerial.h> should be #include ;

Hi David. You can use the AT+CMODE=0 and then AT+BIND=??? to restrict the module to a specific bluetooth device connection. You'll need to use some of the other commands (have a look at this list content.instructables.com/ORIG/FI9/7NJR/IRXT0JIG/FI97NJRIRXT0JIG.pdf) to get the addresses of paired modules. I've not tried it or worked out exactly what to do but the commands seem to be there. I hope this helps.

That's a strange one. I'd go back to basics first. Check you've got the wiring correct. Check your resistors in the voltage divider are giving the right output voltage. Maybe swap them for a logic level converter. Make sure the sketch is using the right pin assignments. If this all checks out add a line in the Serial.available block to send the input character back to the serial terminal to check your key presses are getting through. If that's all Ok try sending actual commands to the BT module in code and see if it responds.

@@BytesNBits From my investigations today, I am guessing that the software serial port is too far off from 38400 baud to communicate with the HC-05 reliably. When I just sent AT, I could see on an oscilloscope that the HC-05 was responding with the correct bit sequence, but the Arduino was not correctly interpreting the bits. To test my hypothesis, I created the program below that uses the HW serial port. I used a cheap ~$10 logic analyzer and pulseview to view the data going in both directions. I could see that the HC-05 was replying properly. I put the 10 second wait at the start since I had to reattach the wires from pins 1 and 0 after downloading the code, and I also needed to start the logic analyzer capture after I started the program. I noticed that the HC-05 replied with an error code at the first "AT ", but it responded properly to the rest of the commands. For me, the software serial port did communicate correctly with the HC-05 at 9600 baud, but it garbled a few characters at 19200. #include "Arduino.h" void setup() { Serial.begin(38400); } void loop() { delay(10000); Serial.write("AT "); delay(50); Serial.write("AT+UART=19200,0,0 "); delay(50); Serial.write("AT+UART? "); delay(100); Serial.write("AT "); while(1); } So, for the HC-05, if you only need to make infrequent changes like password, name, and baud rate, you could just use a program like the above to make the changes.

You'll need one arduino with an HC-05 module that can run as a master. This can then connect and disconnect to other devices.

Hi. On some Arduino models (Uno and Nano) the digital serial port is shared with the serial port used to talk to your PC. If you use these pins for your project you then can't communicate with your PC whilst your code is running. This may be why you're not getting anything on the serial port. Using the software serial port gets around this issue. On boards with 2 hardware ports this isn't a problem.

Hi. Try AT+POLAR=1,0. I think it needs an = rather than the first comma.

@@BytesNBits right, my command is same as you said. Tried with upper case and lower case. No luck

@@bencypg Does it respond to the polar query command - "AT+POLAR?"

@@BytesNBits No.

@@bencypg I'm not sure what to try next?? It looks like that command is just missing from the firmware on your devices. I only have HC06s here so can't confirm it. All the datasheets confirm the command should be there. Are all your devices from the same manufacturer? Is there a datasheet specifically from that supplier? Sorry I can't give you an answer.

Make sure the Arduino can talk to the hc05 first. Then make sure the hc05 is transmitting and you can see it to pair with it.

Hi. You'd need to have a look the the data sheet for your device and see what commands or hardware setup options there are. I know the HC05 has more set up features but I tend to only use them as plug and play connections to a mobile phone.

@@BytesNBits Hi. thanks for the reply. I'm working on a project which consists in send data to a hc-05 bluetooth module from a react native app. In the app, I'm using a react-native-ble-plx plugin to handle with bluetooth communication. But this plugin doesn't find the hc-05 module, I don't know why but, I presume tha this module doesn't work with BLE. And thats why I trying to setup a BLE service and characteristc. Maybe it's the reason to hc-05 never get found. I don't know if it's possible, but, thanks for the tip. I will look in the data sheet to see if find a solution.

@@felipe_ramos Hi. The HC05 and HC06 are not BLE compatible. You'll need a different module. If you do a search on Amazon or eBay for 'ble module' you should find what you're looking for.

@@BytesNBits I was already suspecting about that, but then I found a stack overflow post saying that this it's possible. I spent the whole weekend trying to do this, lol. Today, I was about to give up, and now that you say me this, definitly I will search for another module. thanks man, you earned a subscriber.

Hi. The HC-05 works differently to my HC-06. There should be a small button on the HC-05 unit. You need to hold this in as you turn on the power. This will put it into AT mode so it will talk to you. Set it up as you want and then power off and on again to get it back to normal mode. I hope this works!

Thanks for the codes.