interrupt - external(pin b0)

[colin]

Hi all,

would you guys pls show me how to write an interrupt to trigger a switch(connected to Pin B0) from high to low?
I followed the example (ex_wake.c), however, it worked once, and didn't work after that <- weird, huh?! I'm tring to implement a sleep mode (try put it sleep and weak it up by a switch).

I have a timer interrupt and it works fine. when I have a delay_ms(1000) function in #INT_EXT, void ext_isr(), it also delay my timer2?! I also tried put a printf function and a output_high(R1) function in ext_isr() but it showed nothing. It seems the ext_isr() function didn't call at all. I cehcked the INTCON register, bit 7 should be 1, but it showed 0. when I took out the delay function in ext_isr(), everything became normal.

I'm using Mplab 6.3, PCM 3.176, 16F877, PICDEM 2 Plus, ICD 2

Here's my code (took out unnecessary part):

[PCM programmer]

Here's an example of how you can use INT_EXT with a push-button
switch. I don't have time to integrate it into your Sleep program.
But hopefully it will give you some hints.

#include "16F877.h"
#fuses HS, NOWDT, NOPROTECT, PUT, BROWNOUT, NOLVP
#use Delay(Clock=8000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#zero_ram

//-------------------------------
// GLOBALS

char got_interrupt;
char interrupt_count;

#bit INTF_BIT = 0x0B.1

//-----------------------------
// FUNCTION PROTOTYPES

#int_ext
void int_ext_isr(void);


//=============================
void main(void)
{

// Make pin B0 into an input.
output_float(PIN_B0);

// Enable pullups on all port B pins.
port_b_pullups(TRUE);

// Wait for them to pull up.
delay_us(10);

// Initialize the variables used by the interrupt routine,
// before enabling interrupts.
interrupt_count = 0;
got_interrupt = FALSE;

// Since we have port B pullups enabled, the normal state
// of Pin B0 is a high level. Let's set up the external
// interrupt to occur whenever we get a change from
// a high to a low level.
// We will connect a Normally-open push-button switch to Pin B0.
// The "common" pin of the switch goes to Ground.
// When we press the button, Pin B0 will go to logic low level.
ext_int_edge(H_TO_L);


// Make sure the external interrupt flag bit is cleared
// before enabling external interrupts.
INTF_BIT = 0;

enable_interrupts(INT_EXT);
enable_interrupts(GLOBAL);


// Wait in this loop. Check the got_interrupt flag to see
// if an interrupt occurred. If so, display the count.
// Then clear the flag, wait 50 ms to avoid any "bounce"
// (multiple interrupts) when we press the pushbutton switch,
// which puts Ground on pin B0. Then re-enable interrupts.

while(1)
{

if(got_interrupt == TRUE)
{
printf("%d\n\r", interrupt_count);

// Clear the global flag which was set in the interrupt routine.
got_interrupt = FALSE;

// Wait for debounce period. This allows time for the switch contacts
// to quit bouncing.
delay_ms(50);

// Clear any interrupt which might have occurred during the debounce period.
INTF_BIT = 0;

// Then re-enable interrupts.
enable_interrupts(INT_EXT);
}

}


}
//========================

#int_ext
void int_ext_isr(void)
{

got_interrupt = TRUE;
interrupt_count++;


disable_interrupts(INT_EXT);

}

[colin]

PCM programmer,
thanks for your advice b4 taking off.

thanks again.
Hope your program helps.

[sliders_alpha]

i was looking or that, thanks

[PCM programmer]

The compiler does not clear a peripheral interrupt flag when you call
the enable_interrupt() function. This applies to old versions of the
compiler and to new versions.

For example, these lines do not clear the INTF flag: