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HCS12 ports and vectors.c

Posted by Nobody/Anonymous on June 22, 2005
Maybe this just proves how much of a n00b I am, but I'm just curious why the demos have the vectors.c file modified manually to call the vXXX handlers directly rather than calling them through the events.c handlers (the way that ProcessorExpert prefers).

I presume that there's a good reason, I just want to know what it is :-)

RE: HCS12 ports and vectors.c

Posted by Richard on June 22, 2005
Its just a matter of control and efficiency.

For example, the tick timer code generated by the processor expert creates an ISR called TickTimer_Interrupt(), which clears the timer flag, and calls TickTimer_OnInterrupt(), which would then have to call the standard kernel code. This is two more functions calls than necessary. I have just placed the kernel code directly into the interrupt vector so it is the first thing that executes. Less time and less stack usage.

Likewise the serial ports. It is very handy to use the processor expert to configure the serial port, but the ISR code it generates does not help me test the kernel without more overhead. I just wanted more control over the operation so jump directly to my own ISR.


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