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Hi Guys ,
after some looking around i would like to use a TCXO as the clock source for a pic at 16mhz, although a lot are available at 16.367mhx -16.39mhz ,
has any one had experience using them directly for the pics system clock
also as far as i can tell there is no way to adjust the osc using the pic if its an external osc ?
Cheers
Sheldon
TCXO si a 32.768kHz Oscillators ?
I used the internal 32.768kHz oscillator of a PIC.
the requirement is for temp controlled XTl osc clock input to the pic , so the inernal is not used so that drift wont be an issue ( as much)
the problem lies in that i need to adjust this clock as it ages, this is done by using a OSCtune when having the internal clock , how ever when using a ext osc or xtl osc any adjustment must be external to the PIC
Some / not all TCXO have fine adjustment trim pot built in , but many do not
I looked at external time base chip , but often these are more costly an option for what i have found so far
I believe the best way , at lest at the moment is to use an RTC with the TCXO built in and use the SQW output as a referance ( ds3231 ) with sync from the internal clock to monitor / adjust the OSCtune register ,
Check this out...
http://www.romanblack.com/xoven.htm
and there are a LOT of other articles regarding accurate timing on his web site, here...
http://www.romanblack.com/index.htm#elec
no need a TCXO if low drift allowed !!!
just place a variable capacitor // a fixed one ( say 22 + 22 adj i.e.) on the osc input side for coarse or on the output side for fine adj ...
that's how I proceed for my R/C Pic freq. meters, or my PCB UV box timer ...
Alain
I didn’t know there was an RTC with TCXO built in until now.
If you had a pulse output from the RTC you could figure out when to add or subtract a centisecond from DT’s clock.
Assuming this is about real time, maybe “system clock” just means long term stability at the 16MHz.