HC-05 Bluetooth Reconnect

Projects Networking, Protocols, and Devices
1

I have a few HC-05 Bluetooth modules and they seem to work quite well. I'm able to connect send and receive with them, as well as set the Key pin and use AT commands. The problem I have is that if I connect to a computer, or a phone, while the connection works the first time, they never seem to reconnect automatically.

Is there something I need to do in order for them to reconnect after a power cycle?

They seem to retain the last settings I gave them, but on my laptop I have to delete the device and re-pair anytime the HC-05 has lost power. This doesn't seem very practical when I produce a device to actually use.

Thanks

2

I've never had to re-pair any of the dozen HC-05's that I'm using. When I run a terminal on my computer, I just select the HC-05 from the list of ports, set the port parameters, click connect and I'm in.

If the HC-05 is too far away, it will still try to use the port, but there's no connection so it fails.

3

Goines:
on my laptop I have to delete the device and re-pair anytime the HC-05 has lost power.

Very strange. It seems there are three exercises that you make no mention of:

Since you have been fiddling with it, AT+RESET presumably resets everything to factory defaults. If you try that and all is then OK, you are at fault.

If you try the bluetooth with another device and they keep their pairing, the laptop is at fault. If they don't, Bluetooth is suss.

If the other device is OK with bluetooth but not with laptop, then laptop is definitely not kosher.

Etc., etc.

You should not have to do anything. I have had an HC-06 refuse to pair with a tablet, but if an HC-0x can pair, it should be a one-button re-connect.

4

Hmm... okay, I'll play a bit more. Was seeing the same behaviour with my laptop and phone, and a couple of HC-05's. I will try a full reset on them to be sure.

Could be I just need to better setup the software that uses the Bluetooth connection and it might fix it.

Would toggling the Master/Slave setting help, or have your HC-05 or HC-06's been working fine with factory settings?

Thanks a lot

5

Goines:
Would toggling the Master/Slave setting help,

I doubt it. The only time you should set it to master is when you need the Arduino to be a master, which is probbaly not often.

or have your HC-05 or HC-06's been working fine with factory settings?

The only problem I have had is where my tablet will not talk to my HC-06. I am now a bit suss about the HC-06 but it is fine with laptop and phone. I originally had this down to the tablet, which may still be true.

Note that the HC-05 is a slave by default. I have never changed any factory settings. Ultimately, I will have to face this, as I want an Arduino-to-Arduino connection.

Here is some background which may help but your situation seems very strange. It seems more procedural than software..........

http://homepages.ihug.com.au/~npyner/Arduino/GUIDE_2BT.pdf

http://homepages.ihug.com.au/~npyner/Arduino/BT2way.ino

6

Thanks a lot for the help, managed to get it sorted out and it was a laptop software client configuration issue.

7

Ah. Procedural then, that's a relief.........