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AD76XYZ
Joined: 18 Jun 2012
Posts: 19
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| Interrupt on port b not working |
 Posted: Tue Jul 17, 2012 2:37 am |
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Hi,
I was testing port b interrupt.
Am using.
PIC16F886 @4MHz Internal Osc.
CCS C Version 4.105
I have connected LED on A0 and giving low signal on RB7-RB4 but no LED glow.
The pins RB7-RB4 is high, checked by logic probe.
Please where I did mistake.
Whenever I give logic zero to any of pin RB7-RB4 the LED should glow.
| Code: |
#include "KBD_WakeUp.h"
#use delay(4000000)
#int_RB
#define LED PIN_A0
void RB_isr(void)
{
clear_interrupt(INT_RB);
output_bit(LED, 1);
delay_ms(500);
}
void main()
{
setup_adc_ports(NO_ANALOGS|VSS_VDD);
setup_adc(ADC_CLOCK_DIV_2);
setup_spi(SPI_SS_DISABLED);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_ccp1(CCP_OFF);
setup_comparator(NC_NC_NC_NC);// This device COMP currently not supported by the PICWizard
enable_interrupts(INT_RB);
enable_interrupts(GLOBAL);
setup_oscillator(OSC_4MHZ);
// TODO: USER CODE!!
set_tris_b(0x0F);
ext_int_edge(H_TO_L);
output_bit(LED,0);
while(1)
{
}
}
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Tue Jul 17, 2012 3:25 am |
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Two suggestions:
- Review the PIC16F886 datasheet for the actual pin change interrupt features that are not verbosely explained in the CCS C help or manual.
- Check the INT_RBx constants in 16F886.h to be used with enable/disable_interrupts(). |
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sseidman
Joined: 14 Mar 2005
Posts: 159
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| Posted: Tue Jul 17, 2012 7:08 am |
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| Try putting the #int_RB line right before the function def, without the #define in the middle. Don't know if this is the answer, but it couldn't hurt. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19484
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| Posted: Tue Jul 17, 2012 12:19 pm |
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Sequence of things wrong:
setup_spi(SPI_SS_DISABLED);
Correct syntax is:
setup_spi(FALSE);
The earlier line _enables_ the SPI, but with slave select turned off.
This is an error in the wizard.
| Code: |
void RB_isr(void)
{
clear_interrupt(INT_RB);
output_bit(LED, 1);
delay_ms(500);
}
|
This does _not_ define an ISR handler. and wouldn't work if it did.
You need:
| Code: |
#INT_RB
void RB_isr(void) {
int dummy;
dummy=input_b();
output_bit(LED, 1);
}
|
Note the #INT stuff immediately in front of the routine. This is _required_. Then, you can't clear the interrupt, and this is not required. The _compiler_ will automatically clear the interrupt when the routine exits, but neither you or the compiler can clear this interrupt, _until_ you read the port. It'll set again immediately....
Then:
ext_int_edge(H_TO_L);
does nothing. This is for the INT_EXT, _not_ the interrupt on change feature.
Next, _never_ delay in an interrupt handler. Repeat the mantra a hundred times:
Interrupt handlers should do what they have to do, and exit as quickly as possible. Delays in interrupt handlers should be avoided at all costs.
Finally, check what pins INT_RB works on. You are setting the pins that this uses as outputs. Not goingto get much detection on these pins....
I think you are possibly confusing INT_RB, with INT_EXT, which is on RB0, and is affected by ext_int_edge(H_TO_L). If so, you are enabling the wrong interrupt.....
Best Wishes |
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