How to send AT commands to HC05 with Arduino UNO

Projects Networking, Protocols, and Devices
1

Hi.
I want to change user-pass and baudrate commands to HC05 bluetooth module using with Arduino Uno.

Can anyone help me about connection and sending commands ?

I connected cable with in picture and also used realterm.

bM4Y68.jpg
bM4Y68.jpg1440×810 224 KB

QYgWVk.jpg
QYgWVk.jpg1440×810 240 KB

bM4Y68.jpg
bM4Y68.jpg1440×810 224 KB

2

You need to boot the HC05 with the Key pin at HIGH level.
then you enter the command mode to communicate with the bluetooth chop.

if its floating or low it will pass all your commands over the bluetooth connection instead of against the chip

Johan

3

jl-p:
You need to boot the HC05 with the Key pin at HIGH level.
then you enter the command mode to communicate with the bluetooth chop.

if its floating or low it will pass all your commands over the bluetooth connection instead of against the chip

Johan

dear Johan.
Could you please show me at picture, how can I connect Key pin to Arduino ?

4

Hi wtrk,

in the most cases it's sufficient that rx and tx from your module is set to 3.3V. Not 5V. VCC 5V but not the rx and tx.

I added a divider (10k/20k resistors) and no problems to send AT-commands...

Regards,
MiNo

5

http://www.seeedstudio.com/wiki/images/4/48/HC-05_datasheet.pdf

connect the key(34) pin from the bluetooth shield.
to 3,3v. for example.
And i know most of the HC05 work fine at 5v but its better to use a level convertor to have ttl also on 3,3v

6

I dont have any experience how to connect 10k/ 20k resistor or level convertor ?

Do you have any picture connecting HC05 module with arduino uno while sending AT commands

7

Regards,
MiNo

8

http://www.tec.reutlingen-university.de/uploads/media/DatenblattHC-05_BT-Modul.pdf

In this datasheet there is a drawing / schematic how to connect it to a 5v ttl signal

figure 6. circuit 2

9

Thanks I will try to it