Wheel Encoder library, not fast enough!

Hello,

I am using a Baby Orangutan B-328 to control a motor. The motor has a 256 pulse/rotation quadrature encoder (which is 1024 interrupts considering both falling and rising edges per rotation). I am using the the library “PololuWheelEncoders” to read the encoder, but the ISR is not fast enough. I have tried to only enable the interrupt for one of the the pins but it is not working. I guess the problem is that the interrupt is enabled for pin change. Probably if I change the interrupt to only rising edge (or falling edge) the problem may be solved.
Could you please help me on how to change the pin change interrupt to rising edge interrupt?

Thanks,
Navid

The pin change interrupt responds to any change on the pin. There is no way to specify rising edge, etc.
However, you can specify interrupt on rising edge with the external interrupts INT0 and INT1; see the ATmegaxx8 data sheet.