Recently i’ve found some great codes from Tom Van Baak (Leapsecond) and use them as frequency dividers. You can find the *.hex and *.asm here I’ve burned some PIC 12F675 using a PIC programmer to have some CMOS TTL frequencies for various applications One of them was to use the M100, a great military Rubidium Frequency Standard ,as a master clock for my lab/home. The M100 output, as most frequency standards, it’s a 10 MHz sinewave . PICs should take a frequency clock from 0 to 20 MHz and sometimes they do accepts also sine waves. I’ve tried to do some tests using the M100 sine-wave output, but the results were not optimal . So i’ve used two integrated circuits : the first is the 74HC04B1 the output is redirected to a M74HC14 , an Hex Schmitt inverter to create a square wave. This output was accepted then from the PIC input without problems.
This is the circuit diagram :
According to specifications , it is a divider that works like a synchronous decade counter and using 8-bit logic. The software inside with the CPU , “spins” every 5 million clock cycles the output pin.Accuracy output it is the same as the input one, with jitter less than 2ps !
I’ve used two of them to create a “PPS” section , with respectively a 100us,10ms PPS output plus 1Hz and another one that creates square waves of 100,10 , 1 Hz output.
Here is the final result. Using the oscilloscope i’m monitoring the two output : in this case a 10 ms 1PPS and a 1Hz square wave, all directly from the M 100 .
*edit 14/03/2016
Seems much more stable using two 74HC04B1 instead of the 74HC04B1 coupled with the
M74HC14 .
Delta² 