# Hc05 VERSION:hc05V2.3\_le connection problem **URL:** \ **Category:** Networking, Protocols, and Devices\ **Created:** [March 21, 2025, 8:55am UTC](https://forum.arduino.cc/t/hc05-version-hc05v2-3-le-connection-problem/1365846 "2025-03-21T08:55:09Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![mashar20](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/mashar20/32/1205775_2.png) [@mashar20](https://forum.arduino.cc/u/mashar20)\ **Post date:** [March 21, 2025, 8:55am UTC](https://forum.arduino.cc/t/hc05-version-hc05v2-3-le-connection-problem/1365846/1 "2025-03-21T08:55:09Z")
hc-05 in this version connects to the phone (without password) but does not work in phone applications +PSWD:NO KEY OK It says so in the command, but when I want to change the password, it gives a FAIL error Can anyone solve this problem? ---
**Author:** ![Nick\_Pyner](https://avatars.discourse-cdn.com/v4/letter/n/e8c25b/32.png) [@Nick\_Pyner](https://forum.arduino.cc/u/Nick_Pyner)\ **Post date:** [March 21, 2025, 3:25pm UTC](https://forum.arduino.cc/t/hc05-version-hc05v2-3-le-connection-problem/1365846/2 "2025-03-21T15:25:33Z")
The first thing to do is determine that it really is an HC-05. It sounds rather like it isn't. Some pictures might help. ---
**Author:** ![kanchudeep](https://avatars.discourse-cdn.com/v4/letter/k/f17d59/32.png) [@kanchudeep](https://forum.arduino.cc/u/kanchudeep)\ **Post date:** [March 24, 2025, 3:52am UTC](https://forum.arduino.cc/t/hc05-version-hc05v2-3-le-connection-problem/1365846/3 "2025-03-24T03:52:25Z")
I came across the same modules (sold as HC-05 with version No hc05V2.3\_le) & am facing similar issue trying to setup a connection over Serial Port Profile (SPP). The modules do not have any password as described. Under the Android App 'Serial Bluetooth Terminal', the module gets listed under 'Bluetooth LE' devices. The App is able to connect (probably using a specific BLE protocol) & communication works. Could you resolve the issue? ---
**Author:** ![Nick\_Pyner](https://avatars.discourse-cdn.com/v4/letter/n/e8c25b/32.png) [@Nick\_Pyner](https://forum.arduino.cc/u/Nick_Pyner)\ **Post date:** [March 24, 2025, 4:51am UTC](https://forum.arduino.cc/t/hc05-version-hc05v2-3-le-connection-problem/1365846/4 "2025-03-24T04:51:05Z")
> [@kanchudeep](#): > > the module gets listed under 'Bluetooth LE' devices. Well, I guess that means it is more likely to be a BLE device than a HC-05. And an absence of password also points to that. IF you are using the terminal app by Morisch you might be able to use it to receive a "hello world" just using serial print from Arduino. However, there is a library specific for BLE devices, which should be more reliable. I think its called Bluetooth Serial. I can't tell what you want to resolve, so you might check the Martyn Currey website. His notes on using the HM-10 might be useful. There is a possibility your device is actually an HM-10 under another name. If this proves to be the case, it offers nothing over a real HC-05, even though it is BLE. ---
**Author:** ![mashar20](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/mashar20/32/1205775_2.png) [@mashar20](https://forum.arduino.cc/u/mashar20)\ **Post date:** [March 24, 2025, 12:34pm UTC](https://forum.arduino.cc/t/hc05-version-hc05v2-3-le-connection-problem/1365846/5 "2025-03-24T12:34:07Z")
Thank you for your answer. I managed to connect with the program you mentioned, but when I wanted to send the number 1 and turn on the LED via Arduino, it did not send the data. When I read from the program port, the x or ? symbol is read. The problem is not completely solved. ---
**Author:** ![cattledog](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/cattledog/32/217816_2.png) [@cattledog](https://forum.arduino.cc/u/cattledog)\ **Post date:** [March 24, 2025, 5:35pm UTC](https://forum.arduino.cc/t/hc05-version-hc05v2-3-le-connection-problem/1365846/6 "2025-03-24T17:35:44Z")
> [@mashar20](#): > > but when I wanted to send the number 1 and turn on the LED via Arduino, it did not send the data. When I read from the program port, the x or ? symbol is read. Is the Arduino program expecting the character '1' or the numerical value 1? Is the Serial Bluetooth Terminal app set up to send text or hex? Please post your Arduino program. ---
**Author:** ![avrfrog](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/avrfrog/32/1128376_2.png) [@avrfrog](https://forum.arduino.cc/u/avrfrog)\ **Post date:** [March 28, 2025, 8:01pm UTC](https://forum.arduino.cc/t/hc05-version-hc05v2-3-le-connection-problem/1365846/7 "2025-03-28T20:01:51Z")
Had the same issue with the same module. All mentioned statements are true. So the device works, but there is no pass key available. It is just a fraud of the Amazon dealer to claim it is a HC05 module. ---
**Author:** ![cyprajoker](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/cyprajoker/32/1127877_2.png) [@cyprajoker](https://forum.arduino.cc/u/cyprajoker)\ **Post date:** [April 17, 2025, 1:39pm UTC](https://forum.arduino.cc/t/hc05-version-hc05v2-3-le-connection-problem/1365846/8 "2025-04-17T13:39:18Z")
Hello, I've had the same problems as you. In my situation, when I used the same number of bauds (38400) for both the serial pc and the serial bluetooth, I was able to obtain and read the characters. ---
**Author:** ![cirno9](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/cirno9/32/1126716_2.png) [@cirno9](https://forum.arduino.cc/u/cirno9)\ **Post date:** [April 28, 2025, 6:50am UTC](https://forum.arduino.cc/t/hc05-version-hc05v2-3-le-connection-problem/1365846/9 "2025-04-28T06:50:09Z")
HC-05 with firmware hc05V2.3\_le operated some other way, than popular modules with 2.0-20100601 firmware. 1. This modules can work with BLE stadart, not BT2.0/2.1 only 2. It can process the AT-commands at the powered on, at 9600 baud, ignored the EN pin state 3. Or it can work in AT-command mode at 38400 baud if the button pressed or EN = 1 before its powerd on 4. The password for this version is 6-digits (!), not 4 digits as usualy. ---
**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\ **Post date:** [October 25, 2025, 6:50am UTC](https://forum.arduino.cc/t/hc05-version-hc05v2-3-le-connection-problem/1365846/10 "2025-10-25T06:50:45Z")
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.