Hi, A few days ago, I tried to change the name of the HC05 Bluetooth module via AT commands using the method shown in the picture, and I was able to change it, but when I tried to use it with the phone to control a robot or something else, it appeared in the list of available Bluetooth devices and I was able to pair, but after that I was unable to connect, noting that I tried all the methods to exit AT command mode and most of the time it was in normal mode, but I did not understand the reason for the problem. [photo_2025-04-23_11-17-05]

Before changing the name of the device, did you "forget" the module on your phone? Maybe now you have two device with different name but same MAC address which could be confusing for your app

[image] shahin28: I did not understand the reason for the problem Me neither. Did you try to set the old name? Can you try to connect with another phone?

True, i didn't tried to connect it with another phone.

I connected it to another phone and i got the same problem

And you can exchange AT command with the module? BTW, you're supposed to have a voltage divider on the RX pin of the module. Check on the WEB [image] Also, I recommand using other pins that 0 and 1, that are used by the Arduino to communicate with the computer

Quelle est la fréquence de la LED sur le module ? Essai de l'alimenter depuis une source externe. Pense à mettre un GND commun

on my HC05 module I put a switch between VCC and EN, because when you work in AT mode they must be connected, while when you work in normal mode they are not

I successfully entered AT mode on my HC-05 Bluetooth module (version: hc05V2.3_le) using an Arduino Uno and changed the module name using AT+NAME. However, after that: The module appears in the phone's Bluetooth list and pairs automatically without asking for a PIN Once paired, I can’t connect or communicate with it using any Bluetooth Serial app I tried with two phones (Android), same issue What I Tried: Confirmed AT mode using AT → got OK Tried AT+PSWD=1234 → got FAIL Tried AT+PIN=1234 → got no response Tried AT+CMODE=1 → got FAIL Reset with AT+ORGL → worked, but issue persisted Checked firmware: AT+VERSION? → +VERSION:hc05V2.3_le After reset, module still pairs instantly, no PIN prompt, and won’t send/receive data Wiring is correct, baud rate is 38400 in AT mode, using Arduino with SoftwareSerial. I was able to change the password using 6-digit password but the problem of connecting it to my phone app is not working

HC05 bluetooth AT commands problem

Projects Networking, Protocols, and Devices

anon94801460 April 23, 2025, 4:01pm 18

Please post a link to where you bought the modules. They are mislabeled and don't work as advertised. They appear to have BLE code on them. See this thread:

HC-05 bluetooth module has no password

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HC05 bluetooth AT commands problem

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