Zero-crossing detector?

[ardhuru]

Still with PBP and the 12F683.

I'm looking for (a) transformerless, (b) fewest components, and (c) simplest implementation.

Thanks!

Since you're looking for a transformerless design, you have sacrificed isolation from the mains anyway. Go with the resistor directly to the pic approach. For increased safety, break up the resistor value into 3 series resistors.

Personally, I find the software easier to write if I have positive going transitions for each half-cycle. But to achieve this, you'd need to use an opto with 2 diodes in anti-parallel. I find the PC814 ideal for this.

Regards,

Anand Dhuru