I am using the HC-05 bluetooth module. Now in the first try I have connected it to my HC-05 using Arduino Mega in AT mode and it worked fine. I have pair my phone and connect my bluetooth app and the HC-05 was sending and showing the correct number of sent bits from the phone to the serial monitor.
Now, I have reset my HC-05. Then i tried to go into AT mode again. I did the same thing i did in the first try. This time nothing was showing in my serial monitor for the HC-05. When i type "AT" into the serial monitor i see nothing. When I type "AT+RESET" the HC-05 resets and I can see that the red LED blinks faster. Which means it exited the AT mode.
The only problem now is in my second try nothing is showing up in my serial monitor. When I type "AT", I see nothing. I tried changing the baud-rate to every option available, but nothing shows up on the serial monitor! When i type "AT+RESET" the HC-05 exists the AT mode, but no message shows up into my serial monitor. I can see that the HC-O5 is responding to what i am typing in the serial monitor, but the only problem is that i cannot see anything in the serial monitor. It is just blank white window?!
If anyone now how to solve this problem please help.
CoffeeBrain:
When I type "AT+RESET" the HC-05 resets and I can see that the red LED blinks faster. Which means it exited the AT mode.
This could be down to wiring and/or power, which you need to describe. While you say that Bluetooth is responding to what you type, it could be that it isn't, you just think it is.
I had a similar issue with the HM-10 (not HM-05 but similar) after changing baud.
After I changed the baud via AT command, the next time I went into serial monitor, I had the same issue as you did, i.e. sending AT commands, but not receiving anything back...BUT through several tests, I realized the HM-10 was actually receiving and responding to my AT commands.
I can't remember the exact steps I took to fix it, but it involved sending an AT-RESET command, restarting the HM-10, and also restarting Arduino IDE. Sorry I can't be more specific.
Sorta the classic "restart everything" instructions that computer support people give callers!
Zimbu:
I had a similar issue with the HM-10 (not HM-05 but similar) after changing baud.
Thank you very much Zimbu. I will try to do that hopefully the command comes back in the serial monitor again. It was working fine in the first time, but after 2 mins I wanted to redo the same procedure and nothing shows up in the serial monitor.
Nick_Pyner:
This could be down to wiring and/or power, which you need to describe. While you say that Bluetooth is responding to what you type, it could be that it isn't, you just think it is.
I attach a a good picture of my breadboard. Now Vcc is connected to 5V pin. GND is connected to ground pin. TXD is connected to RX0 pin. RXD is connected to TX0 pin. I also tried to switch the connections of the TXD and the RXD. Still nothing happened!
CoffeeBrain:
I attach a a good picture of my breadboard.
No, you haven't.
I also tried to switch the connections of the TXD and the RXD. Still nothing happened!
The only reasons for switching the connections are that you don't know what you are doing, or what the connections are for. Transmitters transmit to receivers, hence Tx>Rx, no exceptions. If you are using wires, it is good practice to connect Arduino Tx to bluetooth Rx through a 1k/2k voltage divider. It is not usually fatal if you don't.
I assume the 5v for Bluetooth is from Arduino, but you don't say what is powering that. Hopefully it is the USB cable, which indeed should be adequate.
I also assume that you have had things working properly for normal communications before you attempted AT mode. If so, this may well be a simple problem of procedure. Have a look at the Martyn Currey website.
Hello guys i fixed the problem. Here is the solution for everyone having this problem to:
First of all, run the attached code.
Then run an empty sketch.
Put your HC-05 in AT mode and is should work. When you type AT in the serial monitor, every thing will work as intended. make sure the baud is at 38400.
I don't know why that solves the problem, but it works. Now I can use my HC-05 again.
