User`s guide

DAK

KwikNet Overview

Multitasking Operation

In a multitasking system which uses an RTOS, operation of the TCP/IP stack is

controlled by a single task called the KwikNet Task. This task begins execution after your

application calls procedure

kn_enter() to start KwikNet. The KwikNet Task executes at a

priority above that of all other tasks which use

KwikNet services.

The KwikNet Task receives timer ticks from the RTOS through the KwikNet OS interface.

These ticks, KwikNet's fundamental timing source, occur at the frequency which you

specify when you configure your

KwikNet Library.

KwikNet uses its Ethernet, SLIP or PPP network driver to interact with a particular

network's device driver. The KwikNet Task and the device driver cooperate to ensure that

network packet transmission and reception occur in a timely fashion. Interrupts

generated by the device's hardware interface are serviced by an RTOS compatible

interrupt service routine (ISR) which calls the device driver's interrupt handler.

Your application tasks interact with KwikNet using the UDP or IP programming interface

or the TCP or UDP socket services.

At times, KwikNet may be forced to suspend your application task pending completion of

a requested service. How this is done depends on the magic of the KwikNet OS interface.

In a multitasking environment, only the task requesting service is suspended. Other tasks

are free to execute and use KwikNet services. KwikNet and its OS interface resolve the

problems, if any, which may occur when multiple tasks make conflicting demands on the

use of the stack.

If you use any of the optional KwikNet components such as the FTP Server or Web Server,

you will observe that these servers are also implemented as tasks running under the

auspices of the RTOS. These tasks will be of lower priority than the KwikNet Task but

will usually be of higher priority than your application tasks which use KwikNet services.

Finally, note that most applications will probably include one or more tasks of higher

priority than the KwikNet Task. These tasks, although critical for the success of your

application, must not starve the KwikNet Task's demands for execution time.

Note

All application tasks which use KwikNet services MUST

execute at a priority below that of the KwikNet Task.