It seems that the output of IRQ is drain open, it must connect a pullup resistor. In your code, you set IT1=1, thet means if P3^3 goes from High-to-Low will trigger interrupt.
So I think if IRQ is drain open, if has no interrupt, it is state is High Z, and use a pullup resistor, then output will be High. and When a interrupt comes, IRQ will become low, then P3^3 get the High-to-Low voltage, and will trigger uC interrupt.
Hi,RDRyan
thank for your helping . but I have already pull up Resistor to VCC at that pin. Why can't my uC not interupt when Ds12887 ended update data.
To fix your probem, I think you should follow this flow:
First, check when you give a negative clock voltage at P3^3, whether the uC will tirgger the interrupt. if the interrupt is OK, then do the second check. if NOT, check the interrupt register setting, insure the uC will accept and respons interrupt.
Second, check the IRQ of Ds12887, use oscillograph to see whether it has the Hight-to-Low change in the IRQ pin. if NOT, check your init setting of Ds12887.