AVR-Chat

>
> I have asked this on the codevision site also but wondering if anyone here could help.
> 
> I am using a mega16 Int 0 with an encoder, no sleep, WDT or other special items.
> For each detent of the encoder the input to the int 0 goes from 5 - 0.5 - 5 -
> 0.5 and so on, like it is designed to do. I have set the MCUCR to 0x01 for any
> change, but it only responds to a negative change, so I only get an interrupt
> every 2 detents of the encoder, 5 to 0.5 change. Other than this the whole
> program works. I have even tried another chip. I have even tried disabling
> intrupts upon entering the intrupt and enabling it with exiting.
> 
> Why am I only getting a negative change interrupt?
> Is there anything that would interfer with the MCUCR to change the level change
> interrupt settings to only negative change?
> 
> If someone could help off forum would be great! (my code is kinda messy since I
> am a biginner)
> 
> Brian
>

>
> I have asked this on the codevision site also but wondering if anyone here could help.
> 
> I am using a mega16 Int 0 with an encoder, no sleep, WDT or other special items.
> For each detent of the encoder the input to the int 0 goes from 5 - 0.5 - 5 -
> 0.5 and so on, like it is designed to do. I have set the MCUCR to 0x01 for any
> change, but it only responds to a negative change, so I only get an interrupt
> every 2 detents of the encoder, 5 to 0.5 change. Other than this the whole
> program works. I have even tried another chip. I have even tried disabling
> intrupts upon entering the intrupt and enabling it with exiting.
> 
> Why am I only getting a negative change interrupt?
> Is there anything that would interfer with the MCUCR to change the level change
> interrupt settings to only negative change?
> 
> If someone could help off forum would be great! (my code is kinda messy since I
> am a biginner)
> 
> Brian
>

>
> I hope I'm mistaken, but I recall that the older mega's lacked the "pin change" interrupt capability. This has a register where you enable interrupts for a change in state on a given pin.
> Look at the PCICR register explanation for the mega168. I don't think the mega16 has that.

>
> How are you writing to the MCUCR ? the default setting for the interrupt pins is low level detect (iscx1 = 0, iscx0 = 0), sounds like you are not actually setting the required value in the MCUCR, can you verify that the value is as you think it is.
> 
> Regards