Radio Frequency (RF) & Wireless Design

I noticed that there were many CAD modules of the commodity HC-05 (Master) and the HC-06 (Slave) Bluetooth modules in the GrabCAD library and it seems like there are many designers that are copying and inserting any module in their project (e.g. robots, mechanism, ...etc) without understanding that each module serves a specific purpose.

The Master module (HC-05) is the Bluetooth pairing (and bonding) initiator in the firmware and its the device that will start the search for what's out there to be found. This is the module that is typically attached to the Arduino embedded MCU module, which is typically used as the remote controller by the human. The Master sends out all the commands to which the slave device responds. In the case of a robot or car, the motion of the Slave device responds accordingly.

Here's a comparison of the HC-05 and the HC-06 :

http://www.martyncurrey.com/hc-05-and-hc-06-zs-040-bluetooth-modules-first-look/

And for those of you looking for the schematic of the HC-05 module, here you go :

https://eelabs.wordpress.com/2014/04/26/bluetooth-connection-with-arduino-and-control-beep-speaker/

Here is a link that explains the wiring configuration, code, and operation for the HC-05 :

https://www.aranacorp.com/en/arduino-and-bluetooth-module-hc-05/

The Slave module (HC-06) is the Bluetooth end device that is to be controlled. This is the module that is used typically in the robot, mechanism, or other end point that will receive the commands from the Master Bluetooth module (HC-05). Here is a link that explains the wiring configuration, code, and operation for the HC-06 :

https://www.aranacorp.com/en/arduino-and-bluetooth-module-hc-06/

Notice that there are (2) more wires required for the HC-05 than the HC-06 !

Here's the pinout for the HC-05 :

https://components101.com/wireless/hc-05-bluetooth-module

And here's the pinout for the HC-06 :

https://components101.com/wireless/hc-06-bluetooth-module-pinout-datasheet

Also note that although a HC-05 *may* act as a slave, it is intended to be a master, so for those who wish to save money buy not buying two masters, it makes sense to buy (1) HC-05 Master and (1) HC-06 slave.

Here's some additional information about the AT command set :

https://www.instructables.com/AT-command-mode-of-HC-05-Bluetooth-module/

I hope that this helps those who are desiring to use the Arduino platform to create a Bluetooth link to their end point devices.