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ibsumith
Joined: 24 Jul 2009 Posts: 21
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Help needed on Interrupt Latency |
Posted: Fri Aug 28, 2009 4:25 am |
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While writing code in CCs c interrupt Latency is more compared to Assembly???
How could i reduce Interrupt Latency???
which all factors affect interrupt Latency???
Help needed for pic16.......
How much time will take if device is in sleep for servicing ISR??? |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Ttelmah Guest
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Posted: Sat Aug 29, 2009 5:08 am |
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Some other comments:
The question about 'sleep', depends on a lot of factors. First, remember you don't 'need' an ISR. If you have the global interrupt flag disabled, and the interrupt you want to wake up enabled, then go to sleep, the chip wll awaken, on the interrupt, and execute the next instruction. No 'interrupt latency' at all in this sense. Rememebr also though that this following instruction will have been 'pre-fetched' before sleeping, so should not be anything like a value test etc. (nop is the safest thing).
However you then need to look at the actual 'wake up' time. This will depend on your hardware. If (for instance), you are running with the internal oscillator driving a crystal, the chip will not wake up, till the clock is stable. On most chips, 1024 cycles of the lock is allowed for this!..... Far more than the interrupt latency. This delay is only present, in XT, HS or LP oscillator modes. If instead you run with an external clock, and use the EC mode, wake up will be almost instantaneous.
Best Wishes |
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