An empty sketch requires empty setup() and loop() functions:ĪT – test the connection. Choosing the latter, I connected the HC-05 tx pin to the Arduino UNO’s tx pin and its rx pin to the UNO’s rx pin just like in this tutorial.īecause the Arduino will act like the USB-to-TTL converter and nothing else, we need to load an empty sketch to it. The status LED will stay on for 1 second and stay off for another second if in AT Command mode.ĪT Commands are sent to the module serially using a USB-to-TTL cable or an Arduino.

AT Command ModeĪs mentioned, we enter command mode by either connecting the KEY to VCC or keeping the button pressed while powering on. The STATE pin is used to indicate connection status: it’s high when the module is connected to a device and low if not. The EN pin, when pulled low (connected to ground), disables the module. There is still a KEY pin on my version but not readily accessible: We will discuss these commands later.įor my device, AT Command mode is entered by keeping the button pressed and then powering up the module. AT commands are used to configure the module. The KEY pin, when pulled high (connected to 3.3V), is used to allow the HC-05 to enter AT Command mode. When in data mode, the module acts as a wireless bridge between two devices. The HC-05 module has two modes: Data and Command mode.

Your device might have the KEY pin instead of the EN pin. The primary difference between the two is that the HC-06 is a slave only device. There is another bluetooth module, the HC-06, which looks exactly like the HC-05. We’ll be using the HC-05 bluetooth module, a widely available and cheap bluetooth device that is capable of going into master (initiator) or slave (acceptor) device. Today, this technology is popular in connecting two or more mobile devices, particularly smartphones, tablets and laptop computers.

3 Control a LED via Bluetooth and Androidīluetooth is a radio communication protocol that was created as a wireless alternative to the RS-232 serial protocol.

Arduino wifi vs bluetooth iphone 6