Strange Problem Encountered Using MicroChip MPLAB IDE C Compiler

[Pommie]

I just looked at the chip your using, check the function of bit 6&7 of CCP1CON. In fact, I think you can set the chip up so that CCP1 output is inverted - see page 147 of the data sheet.

Mike.

 

[skyflyer54]

Oh, you get the correct result, but not the wanted result
You want the waveform to be inverted, but not the duty cycle to be complemented.
You cannot use this: PORTB = ~CCP1 because the result on PORTB is parallel. The easiest way is to use a hardware inverter at the output of CCP1.

Or, is the program running anything else? If not then you can update the duty cycle of CCP1 in the timer 2 ISR. In the main, poll RC2 (CCP1) and invert this pin to any output pin. Or anyone has better solution?

I'm using the chip to do other things so I think external circuitry is better. Haha

 

[skyflyer54]

I just looked at the chip your using, check the function of bit 6&7 of CCP1CON. In fact, I think you can set the chip up so that CCP1 output is inverted - see page 147 of the data sheet.

Mike.

Hi Pommie,

Haha.. U are waiting for me to describe what i wanted to achieved? Haha... By the way, I seem page 147 of the data sheet. I will set the bits and see whether I can achieve the inverting part. Update again.

Another thing, can PIC do deadtime timing delay?

 

[Pommie]

Hi Pommie,
Another thing, can PIC do deadtime timing delay?

Yes, read section 16 of the data sheet.

Mike.

 

[skyflyer54]

I just looked at the chip your using, check the function of bit 6&7 of CCP1CON. In fact, I think you can set the chip up so that CCP1 output is inverted - see page 147 of the data sheet.

Mike.

Hohoho... Thanks Pommie for guiding me to the datasheet.

I can now do the inverting of the signal already.

I only make the changes on CCP1CON bits 0&1.

CCP1CON = 0b00001111; // Active Low
CCP2CON = 0b00001100; // Active High

Where my PWM become

CCP1 = 0011 1100 &
CCP2 = 1100 0011

As mentions earlier, CCP1CON bits 6&7 don't seem to have effect on my PWM signal as I tried to put it both to '1' and '0'. The output remain the same.

 

[skyflyer54]

Hi All,

I have one more issue that I'm figuring out but I don't know whether i'm write or wrong. Please Advise.

The issue is as follows:

The code that I posted in this forum was doing a forever while loop. I understand that this approach was called "polling". There should be 1 more approach by using the Interrupt which I'm very lost at it.

I would like to have a timer that can count (say 1uS), than after every 1uS, it will call the interrupt to execute some task. Please advise me if the following code is wrong.

#include <P18F4520.h>
#include <timers.h>

#pragma interrupt interrupt_1

void interrupt_1 (void);

void main(void)
{	
	OpenTimer0( TIMER_INT_OFF & T0_8BIT & T0_SOURCE_INT & T0_PS_1_256 );
	if (INTCONbits.TMR0IF=1)
		interrupt_1();		
}

void interrupt_1(void)
{
	// Interrupt Code - For example like reading analog input
}

 

[skyflyer54]

Oopz.. Seem like no1 can comment about how to trigger the interrupt by using a timer ?

Wondering is my approach is correct or wrong...

I have missed out something on the previous part of the code. The following is the new code that I have add in.

#include <P18F4520.h>
#include <timers.h>

#pragma interrupt interrupt_1

void interrupt_1 (void);

void main(void)
{	
	OpenTimer0( TIMER_INT_OFF & T0_8BIT & T0_SOURCE_INT & T0_PS_1_256 );
	if (INTCONbits.TMR0IF=1)
		interrupt_1();		
}

void interrupt_1(void)
{
	INTCONbits.TMR0IF = 0;
	// Interrupt Code - For example like reading analog input
}

 

[Pommie]

If you have a look at this thread, about a dozen posts down I posted some code showing how to setup the interrupt vector and routine. From this you should be able to work out how to do your interrupt.

BTW, a 1μS interrupt is very fast. Are you sure you don't mean 1mS?

Mike.

 

[skyflyer54]

If you have a look at this thread, about a dozen posts down I posted some code showing how to setup the interrupt vector and routine. From this you should be able to work out how to do your interrupt.

BTW, a 1μS interrupt is very fast. Are you sure you don't mean 1mS?

Mike.

Thanks Pommie... I have set up my interrupt and it working now already. The thing that i missed out in my interrupt is the setting of interrupt vector right. ...