Table of Contents

Wireless Serial Port Based on Bluetooth

About this Article

Abstract

Sometimes, the serial port cable between Cubieboard and PC is annoying, because it may mess up your desktop. In this tutorial, two similar approaches are presented to guide you to get rid of the annoying cable, and create a wireless interactive console. In fact, wireless console is quite usefull especially there is no network connection between Cubieboard and PC, or there is no SSH server installed on the Cubieboard. Serial-bluetooth module is quite common and cheap these days, and it is really a good choise to make a wirless serial port connection to PC.

Method one: UART0(ttyS0) directed to serial-bluetooth module

Prerequisite

Hardware

Software

Cubieboard side: ttyS0 should be configured as an interactive console, which means the following configurations should be done

bootargs=console=ttyS0,115200 console=tty0
T0:2345:respawn:/sbin/getty -L ttyS0 115200 vt100

PC side: Serial console clients like minicom or gtkterm(recommended)

Configuration & Connection

Method two: usb serial console to serial-bluetooth module

When installed in a case, like this, Cubieboard's TTL interface would be blocked and can no longer be plugged in the TTL to USB cable. In this case, we could exploit the USB port to make wireless serial port possible. This method is a bit different from method one previously mentioned, especially on the Cubieboard's side. What's more, this method remains the chance of choosing either TTL serial port or USB serial port for wireless console. In a word, this is a safe and flexible method.

Prerequisite

hardware

software

Cubieboard's kernel configuration should be done, enable below fetures(press 'Y' to select)

  1. Device Drivers→USB support
  2. USB Serial Converter support
  3. USB serial console device
  4. The USB serial driver corresponding to the TTL-to-USB serial module, USB Prolific 2303 Single Port Serial Driver in my case.

:!: Do remember, all above features should be compiled into kernel instead of modules.

Like configurations mentioned in method one, the follwing alteration should be done.

bootargs=console=ttyS0,115200 console=ttyUSB0,115200 console=tty0
  
  T0:2345:respawn:/sbin/getty -L ttyS0 115200 vt100
  T1:2345:respawn:/sbin/getty -L ttyUSB0 115200 vt100

:!: That above bootargs & two lines will make both TTL serial port(ttyS0) and USB serial port(ttyUSB0) interactive consoles.

Connection

Both Cubieboard and PC 's USB port will be used for connection.

For those PC has built-in bluetooth device

If your PC has a built-in bluetooth device, the serial-bluetooth module and TTL-to-USB serial module won't be necessary anymore. Most OS can simulate the built-in bluetooth as a serial port(a COM port for Windows, or a rfcomm for Linux). Assuming your OS is Linux, the configurations are described below.

Firstly, install the necessary packages.

$ sudo apt-get install bluez

Secondly, create /dev/bluetooth/rfcomm.conf, input these lines

#
# RFCOMM configuration file.
#

rfcomm0 {
#	# Automatically bind the device at startup
	bind no;
#
#	# Address of the bluetooth device attached to cubieboard
        # This address could be achieved by "hcitool scan"
	device 00:06:69:00:0B:D3;
#
#	# RFCOMM channel for the connection
	channel	1;
#
#	# Description of the connection
	comment "Cubieboard bluetooth device";
}

Thirdly, start the bluetooth service

$ sudo service bluetooth start

Then, bind the target bluetooth to a serial port

$ sudo rfcomm bind /dev/rfcomm0

At last, you can open this port as usual serial ports

$ minicom -D /dev/rfcomm0

Conclusion

References