Electronic – HC-05 Bluetooth module not responding to certain commands

at commandsbluetooth

I've got a problem with my HC-05 BT module. I'm talking to it from my PC via USB/UART converter. When it's in slave mode I can link it with another device, send data using module's and converter's virtual COM ports. But some AT commands seems to be not working. For example, I can't check the module's name. Inquiring also does not work. Here is a sample "chat" I'm having with HC-05:

AT
OK
AT+VERSION
+VERSION:2.0-20100601
OK
AT+UART
+UART:38400,0,0
OK
AT+UART=115200,0,0
OK
AT+UART
+UART:115200,0,0
OK
AT+NAME //No respond to this command
AT+NAME=HC-05
OK
AT+CLASS //No respond
AT+ROLE
+ROLE:0
OK
AT+ROLE=1
OK
AT+INQM
+INQM:1,1,48
OK
AT+STATE
+STATE:PAIRABLE
OK
AT+INQ //My phone has BT and visibility on, so I can test this It didn's find any devices, no "OK" message is shown neither
AT+INQC //About 5 minutes later, I want to cancel inquiring, no respond to this command too
AT+STATE
+STATE:INQUIRING
OK

When I turn the power off and on, it's still inquiring, the only way to stop it is to change it back to slave. Am I doing something in the wrong way? Or my module is simply broken? I'll just mention that it's new, I've unpacked it like 2 days ago.
Anyway, thanks in advance

Best Answer

The answer is in the HC-05 documentation: you have to make sure the Key34 is connected to Vcc when sending some AT Commands. simply hold your button down while pressing ENTER in your terminal. http://www.instructables.com/files/orig/FKY/Z0UT/HX7OYY7I/FKYZ0UTHX7OYY7I.pdf

Related Solutions

Electronic – Bluetooth module

A bit of background first: the distinction between incoming and outgoing RFCOMM (Bluetooth stack protocol for virtual COMs) ports is necessary because it's always one of the communicating devices that initiates the connection (a bit similar to TCP sockets - where you have server and client).

The outgoing COM port is used when the PC initiates the connection to the remote device (opening the port initiates RFCOMM connection to the remote device).
The incoming COM port is used when the remote device initiates the connection.

Once the connection is opened it is bidirectional, regardless of the type.

That said, this Bluetooth module supports both master and slave mode (see manual chapter 2), that's why it advertises 2 RFCOMM/SPP ports, I guess. If you want PC to initiate the connection, use COM6, otherwise use COM7.

Why you see no echo in PuTTY? By default there's no local echo, and you actually shouldn't see any characters you type (unless you short UART_RX to UART_TX, or have some real device attached there to communicate with). The module itself is transparent (in the data mode, that is).

Also, baud rate etc. shouldn't really matter for Blueooth connection - note, that chapter 3.2 refers to configuring the device via physical serial port (UART_RX/TX pins, i.e. from the device side), while 3.3 describes configuring over virtual port (i.e. from the PC side). I somehow feel you're confusing the module sides ;)

This excerpt from the manual is quite important:

To connect to FireFly, browse for services, you should see: “SPP” profile with a virtual COM port. Open this virtual COM port to create a Bluetooth connection. Once connected, the device will be in data mode allowing data to flow in both directions as if the serial port were locally attached to the PC. The device must be in command mode for configuration and programming. To enter command mode type “$$$” (three dollar signs) from either the remote Bluetooth connection or the local serial port connection. You must enter command mode within 60 seconds (configurable by setting the config timer).

Cool module, btw!

Electronic – HC-05 Bluetooth module not recognized by mobile phone

Ok i found the problem.

The HC-05 modules (and probably the HC-06) comes with a Device Class 0 as default. Wich most of the lets say "secure devices" nowdays request the device class to enumerate it corectly.

I've setted the decive class to 00001 (this major class is designed for computers) and finally it was recognized by android without problem.

AT+CLASS=1

It was tested with BlueTerm for Android from Google Play and with the default search for bluethoot devices from comfiguration.

Info can be found:

Related Topic