Bluetooth module HC-05, BT_Board 1.5 configuration AT commands

The easiest way to configure the HC-05 Bluetooth module using AT commands, is by using a USB to TTL converter. The module can be forced into AT mode by pulling pin 34 (Key) high before powering the board on. The LED will then pulse much slower than the previous rapid blinking. The connects for this mode are a baud rate of 38400, 8, N, 1 with CRLF needing to be sent after the commands. (AT\r\n) etc.

The reason for this post is this post I made on HEXUS when I was having an issue getting the module to reply to AT commands

Vcc = 3.3v
Gnd = Gnd
Rx = Rx
Tx = Tx
Key = 3.3v

Remember to not cross Rx and Tx for this mode.

Your device is probably on one of the Bluetooth breakout boards, with Vcc, Gnd, Txd, Rxd, Key and State pins…

You can test the connection by sending ‘AT’ to the device, the device should reply with ‘OK’

Other commands include:
AT+NAME=putnamehere will set the device name
AT+NAME? will echo the name back
AT+ADDR? will echo the address back (NAP:UAP:LAP)
AT+ROLE=numberhere will set the role: 0=Slave role; 1=Master role; 2=Slave-Loop role
AT+ROLE? will echo the role back, more details available online
AT+ORGL will reset settings
AT+UART=baudrate,stopbits,parity sets the baud
AT+UART? echos the baud

For more AT commands for the module see below the line. The PDF was lifted from here: Click me but is pasted below in case the datasheet gets taken offline.


Download the PDF file HC-03/05 Embedded Bluetooth Serial Communication Module AT command set.

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