Hi, I am having a problem with a HC-05 Bluetooth module. I have a HM-10 and have used it with no problem. I have checked many forums with no luck. I can get it to connect and pair with difficulty, to different apps and devices, however the max time is about 10 seconds. It drops connection and soon after shuts down (no led ) or just shuts down. I think the unit is faulty (onboard voltage regulator under load) I have been able to enter AT command mode, with no problems (not shutting down) I measured the following, scamming current- alternating between 6 and 45 milli-amps, paired 20 milli-amps, when it shuts off ( no led) 8 to 14 milli-amps.
Your advice would be appreciated.
How unusual, what board are you using the HC-05 with and what script are you running on the microcontroller? It sounds like there may be an issue with the onboard regulator. Although usually those issues either cause a complete failure of the board or are more inconsistent in the amount of time before failure, but we’ll need to take a closer look at what’s going on with the script first to be able to determine what’s going on with it. Thanks.
I am using a ZS-040 board. The script is from the ARDUINO project hub “ Getting Started with HC-05 Bluetooth Module & Arduino” and I am using the recommended app, Bluetooth Terminal on galaxy a30 phone. I am able to get it to connect and send a command, which appears not to work, then it disconnects and quite often shuts down.
HC05 - Bluetooth AT-Command mode
modified on 10 Feb 2019
by Saeed Hosseini
SoftwareSerial MyBlue(2, 3); // RX | TX
int flag = 0;
int LED = 8;
Serial.println("Ready to connect\nDefualt password is 1234 or 000");
flag = MyBlue.read();
if (flag == 1)
else if (flag == 0)
That’s quite interesting, I’m not seeing any obvious indicators that would cause an error such as that, also it seems clear that it’s almost certainly not a problem with the connection to the board itself, as otherwise you likely wouldn’t be able to interact with it correctly via AT commands. I’d recommend replying to your order confirmation email and link this post (HC-05 Bluetooth shutting down - #3 by Allan101600) we may have a faulty bluetooth breakout in this case. Please let me know if there’s anything else that I can help you with
Yes I have tried other scripts and also tried an old Samsung Ace with different apps. Best I could do was connect, sent one or two commands with no response, followed by disconnection and then possible shutdown.
Hi Everyone, I got a HC-05 through Core and everything is fine, thank you for your responses. My old HC-05 was responding very erratically and I couldn’t find anyone on the web with the same problem. I don’t like to blame a component until I have exhausted all possibilities.It’s good to have such a forum to advise and get feedback.
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