External Interrupt on GP2

[Suraj143]

I'm receiving a continuous 5V square wave pulse 50Hz. I want to detect High to low transition (Falling edge) on GP2.

My question is Do I need to enable internal WPU on GP2? I use PIC12F675.

 

[Pommie]

If you use the IOC (Interrupt on change) function on GP2 then if, when the interrupt triggers, the pin is low it must have just transitioned. You need the WPU if the signal is active low only.

Mike.

 

[Suraj143]

Hi,

I need to use INTF external interrupt flag bit.I set INTEDG to falling edge.In this case do I need the internal WPU enable?

 

[Pommie]

If your signal is driven high then WPU not needed. If open collector then WPU needed. Either way you can enable WPU as it can't do any harm.

Mike.

 

[Nigel Goodwin]

You only need pull-ups if the source is open-collector, as long as it's a normal logic output then no pull-ups are needed.