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Blob
Joined: 02 Jan 2006
Posts: 75
Location: Neeroeteren, Limburg, Belgium
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| INT0 interrupt 18F242 |
 Posted: Mon Jan 02, 2006 6:56 am |
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Hello,
At the moment i'm trying to generate an external interrupt on the PIC 18F24.
i want to generate the interrupt on pin RB0.
but it seems the interrupt is not catched...
the code i use is as below:
#include <18F242.H>
#fuses HS,NOWDT, NOPROTECT, PUT
#use DELAY (clock=20000000)
#use fast_io(A)
#use fast_io(B)
//int i;
//int x;
//int c;
#int_ext
void EXT_ISR()
{
output_high(PIN_A0);
delay_ms(200);
delay_ms(200);
delay_ms(200);
delay_ms(200);
delay_ms(200);
delay_ms(200);
output_high(PIN_A0);
}
/* main() */
void main()
{
/* Set pin A1 to be the blue led */
SET_TRIS_A(0x00);
/* Allow pin B0 to be an external interrupt pin */
SET_TRIS_B(0b00010000);
ext_int_edge(H_TO_L);
enable_interrupts(global);
enable_interrupts(int_rb);
while(1)
{
output_high(PIN_A3);
}
}
Greets,
Blob |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Mon Jan 02, 2006 8:39 am |
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| Code: | /* Allow pin B0 to be an external interrupt pin */
SET_TRIS_B(0b00010000); |
You are configuring B4 as an input but your comment says B0.
| Code: | #int_ext
void EXT_ISR()
{
output_high(PIN_A0);
delay_ms(200);
delay_ms(200);
delay_ms(200);
delay_ms(200);
delay_ms(200);
delay_ms(200);
output_high(PIN_A0);
} |
Change one of the output_high() calls to output_low().
And why do you call 6 x delay_ms(200) when one call to delay_ms(1200) would do the same? |
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Humberto
Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata
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| Posted: Mon Jan 02, 2006 11:26 am |
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| Quote: |
At the moment i'm trying to generate an external interrupt on the PIC 18F242.
i want to generate the interrupt on pin RB0.
but it seems the interrupt is not catched...
|
enable_interrupts(int_rb);
Should be
enable_interrupts(INT_EXT);
I assume you have a pull-up resistor wired from +5V to PIN RB0 or:
port_b_pullups(TRUE); declared in your code.
It is not a good practice to use delays inside an interrupt handler !!!
To 'see' the RB0 interrupt action, the following code should be enough.
(If your compiler version has the output_toggle() function.)
| Code: |
#int_ext
void EXT_ISR()
{
output_toggle(PIN_A0);
}
|
or if it doesn't:
| Code: |
int8 ext_trigger;
#int_ext
void EXT_ISR()
{
output_high(PIN_A0);
ext_trigger = TRUE;
}
void main()
{
while(1)
{
.......
your stuff
.......
if(ext_trigger)
{
delay_ms(200);
output_low(PIN_A0);
delay_ms(200);
ext_trigger = FALSE;
}
}
}
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Best wishes,
Humberto |
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