Processing pre-set Interrupts

[Tom Bottiglieri]

I am having troubles with my encoder. It is a 128 ppr encoder, and at close to maximum shaft RPM, I start to get bad readings from it. I figured this was from the RC trying to process too many interrupts per second, so I know I need decrease the ppr of the encoder.

The way I thought I could do this was by including a true/false check statement in the InterruptHandlerLow() function that would only call the Encoder Handler Function every other time that interrput happened. I tried doing this with if's and switch statements, but neither worked. I still got 128 ticks per revolution.

Heres a sample of the code I am using.

unsigned char loops=0;

void InterruptHandlerLow()     
{     
     if(loops==0)
     { 
         if (INTCON3bits.INT2IF && INTCON3bits.INT2IE) // left encoder interrupt?
		{ 
			INTCON3bits.INT2IF = 0; // clear the interrupt flag [91]
			Left_Encoder_Int_Handler(); // call the left encoder interrupt handler (in encoder.c)
		}
          loops=1;
     }
     else loops=0;
}

Any ideas?

[Kevin Watson]

Originally Posted by Tom Bottiglieri

I am having troubles with my encoder. It is a 128 ppr encoder, and at close to maximum shaft RPM, I start to get bad readings from it. I figured this was from the RC trying to process too many interrupts per second, so I know I need decrease the ppr of the encoder.

The way I thought I could do this was by including a true/false check statement in the InterruptHandlerLow() function that would only call the Encoder Handler Function every other time that interrput happened. I tried doing this with if's and switch statements, but neither worked. I still got 128 ticks per revolution.

Heres a sample of the code I am using.

unsigned char loops=0;
 
void InterruptHandlerLow() 
{ 
if(loops==0)
{ 
if (INTCON3bits.INT2IF && INTCON3bits.INT2IE) // left encoder interrupt?
		{ 
			INTCON3bits.INT2IF = 0; // clear the interrupt flag [91]
			Left_Encoder_Int_Handler(); // call the left encoder interrupt handler (in encoder.c)
		}
loops=1;
}
else loops=0;
}

Any ideas?

Check the magical Encoder FAQ for a possible answer.

-Kevin