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 ...PC-104ExpansionCR16MCS9LEDís9-12 VdcRS232CAN 2.0BCR16MCS9LEDís9-12 VdcRS232CAN 2.0BCR16MCS9LEDís9-12 VdcRS232CAN 2.0B
Embedded Web Server for the CR16
National Semiconductor
Jeff Wright
28
A CR16-based Embedded Web Server Demo
As a simple example of the many potential uses for such an embedded server, a demonstration
system was constructed as illustrated in Figure 24.  The system comprises several CannonBall
evaluation boards all networked over CAN.  One board assumes the role of a gateway from the
TCP/IP spoken by the PC, to the CAN spoken by the network.  Each node’s peripherals may be
controlled and accessed from a standard Web browser such as Netscape or Internet Explorer.   
As Figure 24 indicates, every node may be configured to run a variety of tasks.  Nodes operate in a
manner similar to that illustrated in Figure 16.  The HTTP Web server present on the gateway is
replaced by a “high-level” CAN driver in the nodes.  This CAN driver is responsible for interpreting
browser requests and spawning any required tasks, as well as formatting task results for
transmission over the CAN bus.  At the gateway, the high-level CAN driver maintains a list of active
nodes and their respective configurations.  This allows the user to remotely manage nodes from a
single control point.  Figure 25 is a sample page from the project (as rendered by IE 5.0).  You’ll
notice that the page includes several gif images.  These were included to enhance the look of the
pages, and were located on the PC’s hard drive.  All other html code is embedded within the FLASH
memory of the CannonBall.
Client Browser
Dial- up Connection
Motor Control
All work and no play
makes Jeff a dull boy
LCD Interface
Temperature
Sensor
T
Keyboard
Interface
LED’s
9-12 Vdc
RS232
CAN 2.0B
PC-104
Expansion
PC-104
Expansion
PC-104
Expansion
CAN Bus
CR16MCS9
M
Figure 24.  Embedded Web Server Demo system
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