Help with code

[tmach]

Hello!

I am trying to use the interrupt on RB0 to control pin D1 on my PIC16F874A. I have used an example posted in this forum but I do not get expected output out of pin D1.
Initially I set high on pin D1. On a H to L change on RB0, after 2 sec if RB0 still remains low, I turn pin D1 to low. I turn on the PIC with RB0 connected to high and then connect RB0 to low. I expect to see PIN RD1 go low after 2 seconds. I do not see any change on RD1. It always remains high. Please advice.

mach

*****************************************************
#include <16f874A.h>

#device ADC=10;

#fuses HS,NOWDT,NOPROTECT,NOLVP

#use delay(clock=20000000)

#use rs232(baud=115200, xmit=PIN_C6, rcv=PIN_C7, ENABLE=PIN_C0)

#bit INTF_BIT = 0x0B.1

//Global declares

int settle = 2000;

#int_ext
void INTRB0(void);


main()

{
DELAY_US(10);

ext_int_edge(H_TO_L);

INTF_BIT = 0;

ENABLE_INTERRUPTS(INT_EXT);

ENABLE_INTERRUPTS(GLOBAL);


OUTPUT_HIGH(PIN_D1);

}


#INT_EXT

intRB0()
{
disable_interrupts(INT_EXT);

disable_interrupts(GLOBAL);

delay_ms(settle);

INTF_BIT = 0;

if(!INPUT(PIN_B0)) OUTPUT_LOW(PIN_D1);
}
********************************************************

[Ttelmah]

[tmach]

Yes,
I use a while loop at the end in the main program. But I am using this while loop to implement a softare SPI. For example I use statements such as while(~clk) to wait for clock edge. The code would look something like this:

#INT_EXT

intRB0()
{
disable_interrupts(INT_EXT);

disable_interrupts(GLOBAL);

delay_ms(settle); //Let RB0 settle for 2 seconds

INTF_BIT = 0;

if(!INPUT(PIN_B0)) OUTPUT_LOW(PIN_D1); //if RB0 is still low, disable D1

printf("test");
}


main()
{
output_high(pin_D1); //initially set D1 high
statements;
.....
...
while(1)
{
while(~clk);
statements;;
}

}

Still there is no change on pin D1 even if RB0 changes from H->L. I have added a printf to see if the ISR is operating and I do see printf working each time there is a H->L transition on D1. But the statement
if(!INPUT(PIN_B0)) OUTPUT_LOW(PIN_D1); does not seem to execute.
All I want is regardless of my software SPI, i.e even if the control is waiting for the clock transition, I should be able to process the change on RB0 and set the appropriate signal on D1, because RB0 is a current sense signal and is critical for circuit protection. Please tell me where I am doing wrong.

Thanks

[PCM programmer]

Here are a few comments on your code.
This is not necessarily enough to make your code work,
but it's just a few things that I noted on a quick scan.

#include <16f874A.h>
// The CCS syntax for #device statements does not include
// putting a semi-colon at the end of the line. Remove it.
#device ADC=10;
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=115200, xmit=PIN_C6, rcv=PIN_C7, ENABLE=PIN_C0)
#bit INTF_BIT = 0x0B.1

//Global declares

// In CCS, an "int" is an unsigned 8-bit value.
// This next line will not work.
// An "int" can only hold a number up to 255.
// You need to change the data type to be "int16" instead.
// This is the reason why you were not getting a 2 second delay.
int settle = 2000;

#int_ext
void INTRB0(void);

main()
{
DELAY_US(10);
ext_int_edge(H_TO_L);
INTF_BIT = 0;
ENABLE_INTERRUPTS(INT_EXT);
ENABLE_INTERRUPTS(GLOBAL);
OUTPUT_HIGH(PIN_D1);
// Add the following line to prevent
// the PIC from going to sleep.
while(1);
}


#INT_EXT
intRB0()
{
disable_interrupts(INT_EXT);
You don't have to turn off Global interrupts here.
// It's done automatically by the PIC, in hardware,
// when an interrupt occurs.
disable_interrupts(GLOBAL);
// delay_ms(settle);
// You don't need the following line.
// The compiler automatically puts in code
// to clear the INTF flag at the end of this
// interrupt service routine.
INTF_BIT = 0;
if(!INPUT(PIN_B0)) OUTPUT_LOW(PIN_D1);
}

[tmach]

Thanks, I got it working now.

mach