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HC-05 : how to AT Command mode ?

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Hi everybody,

i have a HC05 module ( the one with pin "EN" ) that I had programmed a year ago with a 115200 baud rate that I now wanted to return to 38400.
I remember that at the time I was not able to immediately modify the parameters of HC05, but I do not remember the procedure that allowed me to do so. Trying to hold down the button of the HC05 and releasing it when the power is on, the LED flashes slowly but if in the serial monitor I write "AT", after pressing enter i do not get "OK".



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Check this link.
In some cases you may want to change some of the configuration setup values. There are two ways to get into Command Mode:

1, Connect the KEY pin high before applying power to the module. This will put the module into command mode at 38400 baud. This is commonly used, and needed if you don't know the baud rate the module is set to. You can use the BlueToothCommandUtility (LINK) for this.
2. Apply power to the module then pull the KEY pin high. This will enter command mode at the currently configured baud rate. This is useful if you want to send AT commands from a microcontroller as the KEY pin can be controlled from one of the microcontroller pins. BUT you need to know the currently configured Baud Rate.

Commands are sent to the module in UPPERCASE and are terminated with a CR/LF pair.


Very nice, i had already tried as you write but I do not know why it was not good. I've manipulated a bit the baud rates of computer and serial monitor. One of these combinations worked :). I'll open a new thread to explain why I wanted to change the HC05 baud rate.
In all cases, thank you very much
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