Loopback, again

After pairing your laptop to the Bluetooth module, your OS should have created a device file / COM port for you. On Linux, it should be /dev/rfcomm*; on mac, it should be /dev/cu.* and on Windows, it should be a new COM port.

We can now test the Bluetooth module with minicom/PuTTY. Because this module doesn't have LED indicators for the transmission and reception events like the serial module did, we'll test the module using a loopback connection:

Just connect the module's TXD pin to its RXD pin using a F/F wire.

Now, connect to the device using minicom/PuTTY:

$ minicom -D /dev/rfcomm0

Upon connecting, the blinking pattern of the Bluetooth module should change to: long pause then blink twice quickly.

Typing inside minicom/PuTTY terminal should echo back what you type.