How to switch HC-05 from DATA mode to AT mode ?

Hello,

Im trying to make a driver to handle HC-05 device and the next step i had to do is to switch between DATA mode to AT mode. Switching backwards it works ( power off EN pin and then send "AT+RESET" ) but from DATA mode i cant reset the module. Any idea how to do that?

PS: Connecting to Vcc of HC-05 to a pin and try to power of power on this pin is not working because the when the pin is in HIGH level the voltage is 2.2V and the HC-05 Vcc must be 3.3V. This happend when the pin is connected to HC-05 Vcc pin, otherwise the voltage on high level of the pin is 3.3V.

In the light of your first para, the PS reads like nonsense. I think you need to be more forthcoming on exactly the type of HC-05 you are using, and which Arduino.

Im using an HC-05 Master Slave Bluetooth Module with Adapter and an Arduino uno. My question is how can i switch from DATA mode to AT mode ( I need to make a program to do that automatically so response with "push a button" or "unplug the Vcc of HC-05 and then plug it again" are not helpful ).

They are helpful to the point that you realise that they work and so all you need do is achieve the same end by other means, like using Uno to control the power supply via a transistor. The mention of the button suggests your bluetooth is 5v, not 3.3v as you suggest it must be. Indeed your sole problem may be inadequate power.

radu96:
Im using an HC-05 Master Slave Bluetooth Module with Adapter and an Arduino uno. My question is how can i switch from DATA mode to AT mode

You NEED to do the following if you want to put the HC-05 into AT mode automatically:
1.) Drive EN pin LOW
2.) Drive HC-05 pin 34 HIGH
3.) Drive EN pin HIGH

That's it

Hello Pwer_Broker

The thing is that the hc-05 is on a breakout board so the only pins i can control are STATE, RXD, TXD, GND, VCC and EN. I took a look on the board and it seems like the EN pin is link to pin 34, so the EN pin is pin34 and from what you are saying i understand that:
1.) Drive EN pin LOW
2.) Drive EN pin HIGH
3.) Drive EN pin HIGH

From what i've been able to tell with my modules is that EN does NOT connect to pin34, but I could be wrong. If you look on the back of the HC-05 there should be some lettering/numbering in big white letters, specifying the breakout model.

What breakout model do you have? I'll try and look at the schematic and see what's actually going on.

EN may be connected to pin 34 of the HC05, STATE may be connected to EN of the HC05. It's very confusing, seemingly same modules have different actual connections.
Probably the best is to take out your multimeter and check how yours is really connected.

wvmarle:
EN may be connected to pin 34 of the HC05, STATE may be connected to EN of the HC05. It's very confusing, seemingly same modules have different actual connections.
Probably the best is to take out your multimeter and check how yours is really connected.

I know this is an old thread, but I just went through the process of figuring out how to put it into AT mode, so here's what I found out.

I bought my modules through Amazon:

I had no connection between any commbination of Pin34, EN, and STATE. I did discover that if I supplied 3.3 Volts to the EN pin at power-up time, it went into AT mode.

Hope this helps someone looking for answers to this problem.

lar3ry:
I did discover that if I supplied 3.3 Volts to the EN pin at power-up time, it went into AT mode.

Did you try using the button?