Start
• Task
Function •
Scheduling
and Timeslice •
Task
Context •
Task
Control Block •
Global
Variables •
Memory
Management •
API
•
Assembly
Functions •
Give
it a Try •
Enhancements
•
References,
Sources & PDF
ENHANCEMENTS
In summary, µexec is
a small, simple to use, simple to port, and yet useful
multitasking executive. Its resource usage is modest,
taking only about 700 bytes on an ’HC11.
With this executive,
even simple embedded programs can be written as multiple
tasks, gaining you the benefit of having a preemptive
executive.
Naturally, there are
plenty of possible enhancements, such as adding the
watchdog timer function that comes with most microcontrollers
to the system. As well, you might choose to modify
the system so that error conditions can be reported
via your system’s output mechanisms (serial port,
LCD, or even just a blinking LED).
Or, why not modify the
system so that it prints out the maximum stack usage
for each task? You can even add a name field to the
task control block so that diagnostics can be printed
with the task’s name.
Richard Man and Christina Willrich are the owners
of ImageCraft, a company which specializes in low-cost
professional ANSI C tools for microcontrollers, plus
’HC12 hardware and BDM debug Pods. You may contact
them via www.imagecraft.com.
