Instant Interrupts - Revisited

[ozion]

Hi Darrel,

Thanks for reply, I will try that your suggestion.

Regards,
ozion

[ra68gi]

Hi Darrel,
I have just started to use the instant interrupts. Previously i had used 8051 and the bascom compiler. I wanted to set priority to the various interrupts similar to the 8051. in the 8051 the lower priority interrupts can be interrupted by the higher priority interrupts. I can see that we can set priority only in 18F series of pic and not in 16F.

Can we not have priority in 16F pics?

Again i think among the high priority interrupts, those interrupts we would like to service it immediately we place their interrupt handler at the top, but i dont think by doing that we can exit the current high priority interrupt service routine to go and attend another interrupt whose interrupt handler is placed before the current executing interrupt's handler. Meaning to say nesting of interrupts is not possible here. One has to wait until the current ISR is finished to enter into another ISR.
Am i right in saying that Darrel? If that is the case then for any time measuring program we must make sure that the ISR of each of the interrupts are so small that they dont cause a large error in measurement.

Please comment.

Raghunathan

[Darrel Taylor]

That's correct.

No priorities for 16F's. It's a limitation of the PIC's, not the Instant Interrupts.

>> then for any time measuring program we must make sure that the ISR of each of the interrupts are so small that they dont cause a large error in measurement.

Unless you use the capture mode of a CCP module, also true.

But if you switch to 18F's, the problem goes away.
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