Contents

Overview

When using the Garcia robot with a Gumstix Verdex host processor, it is recommended to use the supplied aRelay application.  The aRelay application is a gateway between the BrainStem hardware inside the Garcia and a TCP/IP socket interface.  A configuration file for the aRelay allows parameter modification without the need for recompiliing any software. 

You must be comfortable with the following tools and means before attempting an aRelay configuration for the Garcia Gumstix host option. 

• An understanding of the aRelay application tool is necessary before attempting to use this tool onboard the Gumstix Verdex. 
• Basic text file editing ability (possibly using VI ). 
• Gained command line access to the Gumstix Verdex Pro. 
• Established a network connection on the Gumstix Verdex Pro. 
• Properly configured Gumstix Verdex Hosts file . 
• An understanding of runlevels in Unix systems. 

BrainStem, Gumstix and aRelay Configuration

Configuring the aRelay application requires some knowledge about the Garcia - Gumstix configuration.  This includes having a properly configured "hosts" file, being on a network and knowing how you intend to communicate with the aRelay.  A general topology is as follows:

aRelay configuration used in Garcia.

Information common for all Garcia robots is as follows:

• Gumstix Verdex serial port is connected to a BrainStem network.  This connection is on the Gumstix BTUART serial port.  OpenEmbedded assigns this device as /dev/ttyS1
• The BrainStem network is configured to communicate at 38400 baud. 

Certain details will be different depending on how your Garcia Gumstix host is configured.  One configuration setting that may vary will be defining what IP socket port to use for relaying data.  This can be defined by specifying a number typically above 6000.  The default aRelay application setting is to use port 8000. 

aRelay BrainStem Network Communication

Log into the Gumstix and change into the aBinary directory (/home/acroname/aBinary).  From the command line, launch the aRelay application to create a bridge to the BrainStem.  The following example demonstrates a Gumstix Verdex with an IP address of 192.168.1.217.  Issue the following command:

Configuration File Settings for BrainStem Network

The "relay.config" under the /home/acroname/aBinary folder on the Gumstix may be used to store commonly used settings and simplify command line arguments.  For example, to have the aRelay application use IP port 8001, talk to /dev/ttyS1 at 38400, edit the "relay.config" file as follows:

The command line arguments can be simplified down to:

Launching aRelay on Boot

The aRelay application can be set up to launch automatically on boot.  Create a script to launch the aRelay application. 

Install a symbolic link to point to the script to run when the system system enters runlevel 5.  This is specified in the /etc/inittab file on the Gumstix as the default runlevel.  The value "S95" was picked to make sure the Acroname tools script is run last, but before the login prompt. 

Revision History:

• 2009-07-07: Fixed the runlevel issues to make the Acroname tools launch last in the boot process.
• 2009-07-01: Created drawing to illustrate a common configuration setup.
• 2009-07-01: Created page discussing details for using the aRelay onboard the Garcia.