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young
Joined: 24 Jun 2004
Posts: 285
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| interrupt does not work |
 Posted: Thu Jun 02, 2005 9:05 am |
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I have following program
| Code: |
#if defined(__PCM__)
#include <12f675.h>
#fuses INTRC_IO,NOWDT,NOPROTECT,PUT,NOMCLR
#use delay(clock=4000000)
#use rs232(baud=9600, parity=N, xmit=PIN_A0,INVERT)
void LCDSetGeometry();
void LCDReset();
void LCDinit();
void LCDSetBackLight(int8 backlit);
void LCDSetContrast(int8 contr);
void LCDClrScr();
void LCDNewLine();
void LCDCR();
void LCDTab();
void LCDVerTab();
void LCDBackSpaces(int8 bspa);
void LCDSetTab(int8 Stab);
void LCDSetCursorPos(int8 x, int8 y);
void LCDClrLine(int8 x, int8 y);
void LCDSetCursorStyle();
void LCDOnOff(int8 onoff);
int16 count;
#int_ext
void ext_isr()
{
count++;
}
void main()
{
setup_comparator(NC_NC_NC_NC); //setup_comparators(NC_NC_NC_NC); no "s"
LCDinit();
LCDClrScr();
LCDSetCursorPos(0,0);
puts("*Pulse counting*");
count=0;
EXT_INT_EDGE(L_TO_H);
enable_interrupts(INT_EXT);
enable_interrupts(GLOBAL);
while(1)
{
LCDSetCursorPos(1,1);
printf("Num=%lu",count);
}
}
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I want to count every input to RA2, however, the count parameter does not change, and I also put led output, It looks like that the interrupt does not function at all, what is the problem?
thank you |
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drh
Joined: 12 Jul 2004
Posts: 192
Location: Hemet, California USA
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| Posted: Thu Jun 02, 2005 9:17 am |
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Do you mean GP2? The chip powers up with GP2 configured as an analog
input. Try setup_adc(ADC_OFF);
_________________
David |
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young
Joined: 24 Jun 2004
Posts: 285
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| Posted: Thu Jun 02, 2005 9:49 am |
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Thank you. That is it.
I set it
setup_adc_ports (NO_ANALOGS);
now it is changeing the count number, however, I had a new problem
when I put it low (connect to ground) and then connect to +5v, there is a increase of count, it is correct. however, when I connect to +5v, and unplug it from RB2 pin, and replug it to +5v, there is nothing change, when I unpluge it from +5v, it is suppose to be ground right? but the interrupt does not work?
I tried to put a pull down register on RB2 pin, and tried to unplug it from +5V and repluge it to +5v, this time, the count number jumps a lot, it was not increased by one, why? |
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Ttelmah
Guest
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| Posted: Thu Jun 02, 2005 10:27 am |
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The pins are CMOS inputs. They will stay at the voltage you applied for _ages_. There is nothing to make a disconnected pin go either high or low (unless you attach a pull up/down resistor either internally - where available - or externally).
The reason the count jumps a lot, is 'keybounce', If you use a mechanical contact to make a signal like this, as the signal as changed, there can be hundreds of momentary contacts as the surface irregularities come into play. This is why key scanning routines, check a key, then check it again a few mSec latter to allow the bounce time to subside.
Your system is behaving exactly as expected.
Best Wishes |
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