I need help with HC-05 module

Hi, i can connect to it via my pc but i can't put my hc-05 in at-command mode. Can anyone help me ?

What do you mean by command mode please?

it is a mode in which you can give commands to the hc-05 to change all of it’s defaut parameters (master/slave,baud rate,pairing,name,…)
This mode is indicated by the onboard led flashing more slowly and the module replying to the serial comands.


Thanks for your answeer Nick but it doesnt work for me, it is still flashing rapidely.

I find it with bluesoleil and it is named hc-05 so i guess it is the right one (not hc-06) and it is working but i can't manage to put it into AT-command mode.

I’m so happy, i just found the solution :smiley: :smiley: :smiley: :smiley:

During my search i found two solutions that seems to work most of the time :
people said to put the key pin high and then plug VCC or to press the onboard button and then plug VCC.

The first didn’t work for me so when i found the second ( i didn’t see a button on mine ) i thought F**CK some manufacturers must put a button and some must not.

I tought that i had a partially broken module and just now i looked at my module and notice something that made a tilt sound in my head :

Next to the EN/KEY pin, two soldering point not connected on any side of the pcb and an empty emplacement for … a BUTTON !?!

So it seems that i got the exemplary made by some chinese manufacturer to lazy to properly copy a product.


I took a breadboard wire,connected the two point, plugged in vcc and voilà slow falshing of the onboard led.
When i entered “AT” into the seriel monitor it gave me ok as an answer.

Thank you for reading.

I hope it can help other people having the same problem.

Nice finding, congrats!

Thank you!! Your solution is perfect :) :) :) :)

Actually this following solution worked for me!

Connect the BT module with UNO the following way!

Vcc -----> 5V GND ----> GND Rx ------> Rx Tx ------> Tx

power up the Uno, once done, Press the small button in the BT module. Actually, Now the module has entered AT mode (Although the led blink rate will not change).

Now open up the serial Monitor and set the baudrate to 9600 and Both NL&CR ....

Type AT and Module should be replying OK!


Hi there.

I've one BT module with button, but there's any LED that blink. And trying those solutions I don't have a response to command "AT".

Any idea? I'm using this connection schema: http://diymakers.es/wp-content/uploads/2014/02/comandos-At-HC-05.png