Real time clock

[Labjac]

Hallo

I need to implement time stamping with data being captured, using a pic16f690, can anybody tell me what the easiest way would be, do I need to get an external chip for date and time, or do you normally create a "watch" with the internal timer on the pic?

Regards,
Labjac

[temtronic]

It all depends on how the PIC will be used.

A software clock,like ..
http://www.ccsinfo.com/forum/viewtopic.php?t=26177 ( hope it's the correct link). is a nice tight(small code) ISR driven 'real time clock', but has to be setup everytime the PIC is powered up. Either manually with real data or just stuff zeros in (making it more of an elapsed time clock).
It costs you nothing just some code, and can be plain(time only) or fancy(time,date,dow). But it does take time( ISR) to make it run.

A hardware clock, like the DS1307(my choice) requires a battery,xtal,space but is more 'stable' in the long run. It may require more code( the driver) as it's an I2C device,2 I/O pins.

I've done both and chose the DS1307 for all my products.Today PICs have lots of pins, tons of memory and low cost so there's no real reason to not use the hardware solution. I use the software I2C driver from here and a big coin cell battery good for 10-12 years. Spend an extra 50c on a better 'watch' crystal and the timing is bang on. I use the 1 Hz o/p of the DS1307 to trigger a tight ISR and that's the 'heartbeat' for a lot of my projects.

Simple, cheap, reliable and 100% transportable to any other PIC in future projects.

I suggest you try both. Code the software one while waiting for the DS1307 to arrive and then code for the DS1307. Compare code space required and 'flexibility' for your requirement.

Neither choice is 'wrong' it's which one is better for you that is 'right'.

[Labjac]

Thanks

I ordered the chip and will start with internal timers soon.

Regards,
Labjac