The 24bit counter counts up to 9999999 then is reset to 0 to get a PPS out of a 10MHz clock. The most significant bit is high from 0x800000 to 0x98967F, so that you have a 161.1392ms wide high pulse when driving the PPS output with the MSB.
On Thu, Feb 28, 2013 at 1:28 PM, Herbert Poetzl <[email protected]>wrote: > On Thu, Feb 28, 2013 at 01:26:17AM +0100, Azelio Boriani wrote: > > First try at a simple GPSDO for the RaspberryPi. See here: > > http://www.c-c-i.com/exchange/ for the file PiAutoTIC1.zip > > Thanks to Bob Smither for his file exchange site. > > Pardon my ignorance, but where does the 161ms PPS length > come from? > > 2^24 = 16777216 so with 50/100ns clock intervals, we > should either see 83.88ms or 167.77ms (typo?) > > Otherwise, nice project, thanks for sharing and thanks > for releasing it as open-source (btw, you might want > to use some license, like GPLv2 for that). > > Nitpick: the SI symbol for second is 's' not 'S', i.e. > lowercase instead of upper, because 'S' stands for > siemens (which is the SI unit of electric conductance) > > thanks, > Herbert > > > This project is completely open-source, VHDL and C sources are > > available. Can be implemented also with any uP but the C source > > must be heavily modified. > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
