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port C as interrupt

 
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halides



Joined: 28 Oct 2006
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port C as interrupt
PostPosted: Mon Mar 19, 2007 2:30 am     Reply with quote
Hi Friends,

m trying to replace my ISRs (ext interrupts) from portC interrupts.
I just came to know that PORT C PIN4,5,6,7 can be used as change detection pins, but i dont have any idea how to do this.

I want to detect the pulses at these pins and each pulses are some events occuring continuously.

any help in this matter will be highly appreciated.

~halide~
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Humberto



Joined: 08 Sep 2003
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PostPosted: Mon Mar 19, 2007 4:45 am     Reply with quote
Could you pls tell us wich PIC are you using ? In all the 16F series with these capabilities,
this feature is in PORT B.

Humberto
halides



Joined: 28 Oct 2006
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i am using 18f series controller 4550
PostPosted: Mon Mar 19, 2007 5:04 am     Reply with quote
i am using 18f series controller 4550
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Humberto



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PostPosted: Mon Mar 19, 2007 5:16 am     Reply with quote
May be you misunderstood something.
Download the PIC18F4550 from Microchip website and read Chapter 9 Interrupts (P.99)
http://ww1.microchip.com/downloads/en/DeviceDoc/39632D.pdf

Then read how to implement an interrupt on change:
http://www.ccsinfo.com/faq.php?page=int_ext_button

Then post what do you want to do.


Humberto
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PostPosted: Mon Mar 19, 2007 5:51 am     Reply with quote
i go thro your direction, but that i know very well.
pin 0, 1 and two of port B are used as ext interrupts.

#INT_RC //Port C any change on C4-C7

tell me the meaning of this line....... it could be possible that i misunderstood it.

what i want is,,,

can i use portC pin 4,5,6,7 as external interrupt pin......?
KaraMuraT



Joined: 16 May 2006
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PostPosted: Mon Mar 19, 2007 6:11 am     Reply with quote
No you can not...

18F4550 Datasheet Page 99:

Quote:

For external interrupt events, such as the INT pins or the PORTB input change interrupt, the interrupt latency will be three to four instruction cycles. The exact latency is the same for one or two-cycle instructions. Individual interrupt flag bits are set regardless of the status of their corresponding enable bit or the GIE bit.


You can see all the sources as a graph on page 100.
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PICoHolic



Joined: 04 Jan 2005
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PostPosted: Mon Mar 19, 2007 8:55 am     Reply with quote
You can have interrupts on PORTC using tricks, for ex: CCP1 and CCP2 could be used as external interrupt, Rx too ... etc ...

But you have to be careful...
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