Re: [time-nuts] DS3231m 1HZ output stability
Do you have a scope? Any overshoot/bounce crap? (Not likely with low power CMOS.) Attached is screenshot from USB-based scope. I'll going to switch wires to see any difference. -- WBW, V.P.attachment: gps2rtc.PNG___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] DS3231m 1HZ output stability
To answering myself: I think nothing wrong with DS32XX. I hooked up GPS 1PPS output to the same timer (different channel) where I have 1PPS from RTC. Now I see something like this. # Delta GPS: 7330, Delta RTC: 7330 # Delta GPS: 7330, Delta RTC: 7329 # Delta GPS: 7330, Delta RTC: 7329 # Delta GPS: 7330, Delta RTC: 7330 # Delta GPS: 7330, Delta RTC: 7330 # Delta GPS: 405, Delta RTC: 705 # Delta GPS: 405, Delta RTC: 705 # Delta GPS: 7330, Delta RTC: 7330 Definitely something wrong with my code or the way how MCU handle different events (interrupts). Reggards, V.P. On 2014-02-25 17:32, Tom Van Baak wrote: I would like to ask if somebody did measurement for that Dallas DS32XX series chips. Is that 1PPS (1HZ square wave) stable there or it has some issues ? I am thinking that burp in my tests could be because of my poor code or may be because of DS32XX doing temperature conversion every second, which cause an impact to the 1HZ output. I would be interested to hear any information about. From the datasheet of DS3231m , that 1HZ from DS32XX should be stable. Both the GPS and DS32XX 1PPS should be fine. Are your free-run counters really free? It looks like a simple bug in your code. All this is very easy to debug if you have even the most basic frequency or time interval counter available to independently validate the GPS or the DS32XX 1PPS interval. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- WBW, V.P. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] DS3231m 1HZ output stability
I would like to ask if somebody did measurement for that Dallas DS32XX series chips. Is that 1PPS (1HZ square wave) stable there or it has some issues ? I am thinking that burp in my tests could be because of my poor code or may be because of DS32XX doing temperature conversion every second, which cause an impact to the 1HZ output. I would be interested to hear any information about. From the datasheet of DS3231m , that 1HZ from DS32XX should be stable. Both the GPS and DS32XX 1PPS should be fine. Are your free-run counters really free? It looks like a simple bug in your code. All this is very easy to debug if you have even the most basic frequency or time interval counter available to independently validate the GPS or the DS32XX 1PPS interval. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] DS3231m 1HZ output stability
# Delta GPS: 3659, Delta RTC: 3660 # Delta GPS: 3659, Delta RTC: 3659 # Delta GPS: 3658, Delta RTC: 1984 # Delta GPS: 3658, Delta RTC: 1984 # Delta GPS: 3659, Delta RTC: 3659 # Delta GPS: 3659, Delta RTC: 3660 I would like to ask if somebody did measurement for that Dallas DS32XX series chips. Is that 1PPS (1HZ square wave) stable there or it has some issues ? I am thinking that burp in my tests could be because of my poor code or may be because of DS32XX doing temperature conversion every second, which cause an impact to the 1HZ output. I would be interested to hear any information about. From the datasheet of DS3231m , that 1HZ from DS32XX should be stable. My guess would be a software bug, but I don't know anything about what you did there. You might try swapping the two input wires. Do you have a scope? Any overshoot/bounce crap? (Not likely with low power CMOS.) Notice that the 2 strange lines came when the GPS had only 3658 ticks. I have data from one of the DS32xx chips, but I was looking at a 32KHz signal rather than the a 1 Hz. I don't remember any quirks. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
