CCS :: View topic - INT0 interrupt 18F242 http://ccsinfo.com/forum/viewtopic.php?t=25558&highlight=inte...

1 от 3 01.3.2007 г. 11:24

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INT0 interrupt 18F242

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Blob

Joined: 02 Jan 2006Posts: 3Location: Geistingen, Limburg, Belgium

INT0 interrupt 18F242Posted: Mon Jan 02, 2006 6:56 am

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()

{

CCS :: View topic - INT0 interrupt 18F242 http://ccsinfo.com/forum/viewtopic.php?t=25558&highlight=inte...

2 от 3 01.3.2007 г. 11:24

/* 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

_________________

IMEC rulez

ckielstra

Joined: 18 Mar 2004Posts: 1334Location: The Netherlands

Posted: Mon Jan 02, 2006 8:39 am

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?

Humberto

Joined: 08 Sep 2003Posts: 813Location: Buenos Aires la Reina del Plata

Posted: Mon Jan 02, 2006 11:26 am

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.)

CCS :: View topic - INT0 interrupt 18F242 http://ccsinfo.com/forum/viewtopic.php?t=25558&highlight=inte...

3 от 3 01.3.2007 г. 11:24

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; } } }

Best wishes,

Humberto

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