HBBR Basic

Making SLIP connection (Part1)

Serial Line Internet Protocol (SLIP) is a protocol developed for carrying TCP/IP protocol data over point-to-point serial connections. SLIP originated in the 1980s and has been widely adopted but strangely it is not an official standard!

Since SLIP is using serial line as a physical interface, it is very well suited for ARM based microcontroller boards. Typical boards come with at least one serial interface with many boards adding a second one. Board with dual serial interface allows for easy connection to the host computer and convenient debugging. For this reason code presented in this tutorial has been written for a board supporting 2 serial connections. One connection is used for all of the debugging and logging messages while the other one is used for TCP/IP. However, code can be is easily adapted to a board supporting only one serial connection.

Connections

Diagram below shows serial connections between board and computer for a setup with 2 serial interfaces:

Create Project

Once the board is connected create TCPIP project and add following files:

• Runtime module, use XXXXXX_io.mod with HAL Serial class

• TCPIP.bas - MAIN source file

• SLIP.bas - SLIP implementation

All files can be downloaded from Download section on Hobby-Robotics website.

TCPIP.bas

SLIP.bas

Configuring UARTs

Be sure to configure both UARTs UART0 and UART1. Settings do not have to be identical but it will make it easier to debug if both baud rates are set to 38400 which is default setting for the HBBR IDE and runtime.

Compile and upload to Flash

Configuring SLIP on Windows computer

At this point microcontroller side is ready for connection but host computer needs to be configured for SLIP connection.

Configure SLIP connection with the following settings:

General Tab:

General Tab Configure…:

Options Tab:

Security Tab:

Networking Tab:

TCIP/IP and SLIP protocols have been supported on Windows since introduction of the Winsock in Windows 95. However, details of setting and configuring the SLIP very between different versions. Please check documentation for your version. Below are links with additional information for selected Windows versions:

Windows XP

Configuring SLIP under Windows XP - PDF document

Windows ME

How to Connect to the Internet Using the Internet Connection Wizard in Windows Millennium Edition

Windows 98/95

How to Connect to the Internet in Windows 95 and Windows 98

See: - How to Create and Configure a New Connection for SLIP Accounts - How to Connect to Your SLIP Account

Opening Connection

Connect HBBR IDE terminal and reset microcontroller, "Waiting for SLIP connection" message should be displayed.

Initiate connection on the host computer, again details will depend on the version. On Windows XP go to "Start" then "Connect To" and choose the configured SLIP connection.

If everything went OK and connection has been established then HBBR IDE terminal window will show following messages:

Char C
Char L
Char I
Char E
Char N
Char T
Challenge CLIENT
Response CLIENTSERVER
SLIP connection established

Verifying Connection

On the PC SLIP connection can be verified by checking connection status. The images below show the status as reported by Windows XP.

Some common issues

Part 2 : IP Protocol Basics