PICs and keeping time

[ljcox]

Note that Nigel's circuit provides a full wave rectified signal so it will be 100 Hz (assuming your mains frequency is 50 Hz)

 

[Nigel Goodwin]

Note that Nigel's circuit provides a full wave rectified signal so it will be 100 Hz (assuming your mains frequency is 50 Hz)

Yes, it's a zero-crossing circuit, so gives a pulse every zero-crossing. If you want 50Hz, feed it through a flip flop.

 

[NJ Roadmap]

I figured that out, thanks

I am still keeping my options open as I'm not implementing an external clock for time-keeping until after Xmas.

Has anyone worked with using RF to update time? What kind of circuit would I be looking for?

p.s. I've never built an RF circuit before!

 

[Nigel Goodwin]

I figured that out, thanks

I am still keeping my options open as I'm not implementing an external clock for time-keeping until after Xmas.

Has anyone worked with using RF to update time? What kind of circuit would I be looking for?

p.s. I've never built an RF circuit before!

There's a radio transmission from the atomic clock at Rugby, Maplin used to sell kits for it. You can also get accurate time from a GPR receiver or module.

 

[NJ Roadmap]

Yes I know about the radio transmission from Rugby. Just wondering how I'd implement a circuit to receive it and code my PIC to interpret the signal. I'm trying to look for alternatives to a zero-crossing detector or a crystal. This seems like a viable one, so I'm essentially looking for resources on it.

I am googling right now, but if someone has info on what kind of signal it is, whats the modulation and what kind of receiver circuit it needs, it would be nice if they post it up

 

[picasm]

For the receiver you can modify a MSF radio controlled clock cheaper than buying a module and easier than making a receiver from scratch.

The protocol you need to decode is described on the NPL website:
**broken link removed**