Re: [time-nuts] Generate 1 PPS signal on serial port
Having a Linux/FreeBSD PC synchronized using NTP/chrony, what would be the best way of generating an output 1 PPS signal on a (hardware) serial port ? I haven't tried it. On Linux, /drivers/pps/generators/Kconfig (from kernel-devel or kernel sources) says: # PPS generators configuration # comment PPS generators support config PPS_GENERATOR_PARPORT tristate Parallel port PPS signal generator depends on PARPORT BROKEN help If you say yes here you get support for a PPS signal generator which utilizes STROBE pin of a parallel port to send PPS signals. It uses parport abstraction layer and hrtimers to precisely control the signal. Documentation/pps/pps.txt (from kernel-doc) has a section on that. Thanks, I'll check the documentation. ___ 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] Generate 1 PPS signal on serial port
Marki the smart search engine came back with: Prof David Mills: http://www.eecis.udel.edu/~mills/ntp/html/pps.html Pulse-Per-Second (PPS) Signal Interfacing Hardware: http://www.vk2hmc.net/blog/?p=583 If using Linux you need kernel version 2.6.39.4 or version 3 kernel as the PPS interface is now included in the kernel. Unless of course, low latency and jitter is not an issue for you ;) You can use either parallel or serial PPS. For windows see http://www.davehart.net/ for binaries. David Taylor pretty much covers it here: http://www.satsignal.eu/ntp/NTP-on-Windows-Vista.html Thanks, but I need it the other way: the PC itself should generate the 1 PPS signal without an external reference, except the network connection to NTP servers. It's more of a software problem. ___ 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] Generate 1 PPS signal on serial port
I am not really sure what you are trying to do either.. If you are trying to tee the output of a GPS, make a Y cable and connect TxD from GPS and DCD to each end (as PPS and NMEA are broadcast or one way if you like) once the receiver has been configured. You will have timenuts having strokes if you try and do it in software! However if you are hell bent on generating PPS in software somehow (please let me know you plan? - curious) Use http://www.curioustech.net/xport.html Been around for years and its pretty good and free to boot. Or am I still looking at your problem from the wrong end? Personally, I am moving my NTP server to the parallel port shortly. --marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Eugen Sent: Tuesday, 6 August 2013 10:32 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Generate 1 PPS signal on serial port Marki the smart search engine came back with: Prof David Mills: http://www.eecis.udel.edu/~mills/ntp/html/pps.html Pulse-Per-Second (PPS) Signal Interfacing Hardware: http://www.vk2hmc.net/blog/?p=583 If using Linux you need kernel version 2.6.39.4 or version 3 kernel as the PPS interface is now included in the kernel. Unless of course, low latency and jitter is not an issue for you ;) You can use either parallel or serial PPS. For windows see http://www.davehart.net/ for binaries. David Taylor pretty much covers it here: http://www.satsignal.eu/ntp/NTP-on-Windows-Vista.html Thanks, but I need it the other way: the PC itself should generate the 1 PPS signal without an external reference, except the network connection to NTP servers. It's more of a software problem. ___ 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. ___ 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] Generate 1 PPS signal on serial port
On Tue, Aug 6, 2013 at 4:07 PM, Mark C. Stephens ma...@non-stop.com.auwrote: However if you are hell bent on generating PPS in software somehow (please let me know you plan? - curious) FWIW: Over in the hobby-CNC world where it is common to use the parallel port for driving machine tools (mills, lathes, 3d printers) pulses with good timing are output by LinuxCNC which sits on top of a real-time kernel (RTAI, Xenomai, or RT-Preempt). With a well-behaving bios/cpu/motherboard combination it is possible to achieve around 10-20 us maximum jitter - in good cases down to 5 us. The same program run on a non-realtime kernel will easily show 3-5 milliseconds or more of jitter. This is relative to a clock that the real-time kernel uses for internal timing - I am not sure if that clock can be NTP-disciplined. Anders ___ 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] Generate 1 PPS signal on serial port
On Tue, Aug 6, 2013 at 5:31 AM, Eugen eu...@lavabit.com wrote: Thanks, but I need it the other way: the PC itself should generate the 1 PPS signal without an external reference, except the network connection to NTP servers. It's more of a software problem. The current Linux kernel has a PPS GENERATOR. See pps_gen_parport Put WHY would you need this? The documentation for pps_gen_parport suggests only using it for crude synchronization of sevel computers but NTP would in every case work better for that purpose. But for whatever reason Linux does PPS in both directions Be warned that any software PPS gignal will not be great, expect a few microseconds or error Chris Albertson Redondo Beach, California ___ 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] Generate 1 PPS signal on serial port
On Tue, 6 Aug 2013 13:07:28 + Mark C. Stephens ma...@non-stop.com.au wrote: I am not really sure what you are trying to do either.. If you are trying to tee the output of a GPS, make a Y cable and connect TxD from GPS and DCD to each end (as PPS and NMEA are broadcast or one way if you like) once the receiver has been configured. You will have timenuts having strokes if you try and do it in software! However if you are hell bent on generating PPS in software somehow (please let me know you plan? - curious) Use http://www.curioustech.net/xport.html Been around for years and its pretty good and free to boot. Or am I still looking at your problem from the wrong end? Personally, I am moving my NTP server to the parallel port shortly. --marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Eugen Sent: Tuesday, 6 August 2013 10:32 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Generate 1 PPS signal on serial port Marki the smart search engine came back with: Prof David Mills: http://www.eecis.udel.edu/~mills/ntp/html/pps.html Pulse-Per-Second (PPS) Signal Interfacing Hardware: http://www.vk2hmc.net/blog/?p=583 If using Linux you need kernel version 2.6.39.4 or version 3 kernel as the PPS interface is now included in the kernel. Unless of course, low latency and jitter is not an issue for you ;) You can use either parallel or serial PPS. For windows see http://www.davehart.net/ for binaries. David Taylor pretty much covers it here: http://www.satsignal.eu/ntp/NTP-on-Windows-Vista.html Thanks, but I need it the other way: the PC itself should generate the 1 PPS signal without an external reference, except the network connection to NTP servers. It's more of a software problem. ___ 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. ___ 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. No, I don't use a GPS or other synchronization hardware. The PC uses only network communication with NTP, and the PC itself should output an 1 PPS signal on a port serial / parallel. I want to analyze the 1 PPS signal generated by the PC and the synchronization process or to compare two 1 PPS signals generated by different computers. ___ 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] Generate 1 PPS signal on serial port
Hello, On 06.08.2013 17:25, Chris Albertson wrote: The current Linux kernel has a PPS GENERATOR. See pps_gen_parport Put WHY would you need this? The documentation for pps_gen_parport suggests only using it for crude synchronization of sevel computers but NTP would in every case work better for that purpose. But for whatever reason Linux does PPS in both directions Be warned that any software PPS gignal will not be great, expect a few microseconds or error There are applications for that... I had to do that some time ago, since I was required to send a PPS signal aligned to UTC, and a time-stamp of this PPS signal using MIL-1553 (surely this is familiar to some people in the list). The time was the UTC time at the computer (well, in this case an embedded one, ntp sync'd through LAN). Since at that time (not that long ago) there was not a pps generator available in the linux kernel, I developed a small kernel module to drive an ouput pin. It worked nicely enough, with a few microseconds of error - completely tolerable in that application. Regards, Javier ___ 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] Generate 1 PPS signal on serial port
I want to analyze the 1 PPS signal generated by the PC and the synchronization process or to compare two 1 PPS signals generated by different computers. OK, but that just kicks the question further down the road. WHY would you want to compare two PPS signals? It is easy to do as Linux now has a PPS generator built-in. There is nothing to do but configure it. Expect the PPs to have a random 2 uSec or more jitter. It could be much worse. I think the PPS generation uses timer interrupts. The timer advances in uSec ticks and then there is some latency so expect and error in the range of a 'handful of uSec. -- Chris Albertson Redondo Beach, California ___ 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.
[time-nuts] Generate 1 PPS signal on serial port
Probably this was asked before but in searches I only find how to use an external 1 PPS GPS signal for NTP synchronization. Having a Linux/FreeBSD PC synchronized using NTP/chrony, what would be the best way of generating an output 1 PPS signal on a (hardware) serial port ? For timing I've seen the standard libc functions from sys/time.h, like setitimer(), but maybe there are better ways for generating precise delays. ___ 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] Generate 1 PPS signal on serial port
Having a Linux/FreeBSD PC synchronized using NTP/chrony, what would be the best way of generating an output 1 PPS signal on a (hardware) serial port ? I haven't tried it. On Linux, /drivers/pps/generators/Kconfig (from kernel-devel or kernel sources) says: # PPS generators configuration # comment PPS generators support config PPS_GENERATOR_PARPORT tristate Parallel port PPS signal generator depends on PARPORT BROKEN help If you say yes here you get support for a PPS signal generator which utilizes STROBE pin of a parallel port to send PPS signals. It uses parport abstraction layer and hrtimers to precisely control the signal. Documentation/pps/pps.txt (from kernel-doc) has a section on that. -- 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.
Re: [time-nuts] Generate 1 PPS signal on serial port
Marki the smart search engine came back with: Prof David Mills: http://www.eecis.udel.edu/~mills/ntp/html/pps.html Pulse-Per-Second (PPS) Signal Interfacing Hardware: http://www.vk2hmc.net/blog/?p=583 If using Linux you need kernel version 2.6.39.4 or version 3 kernel as the PPS interface is now included in the kernel. Unless of course, low latency and jitter is not an issue for you ;) You can use either parallel or serial PPS. For windows see http://www.davehart.net/ for binaries. David Taylor pretty much covers it here: http://www.satsignal.eu/ntp/NTP-on-Windows-Vista.html --marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Eugen Sent: Tuesday, 6 August 2013 9:47 AM To: time-nuts@febo.com Subject: [time-nuts] Generate 1 PPS signal on serial port Probably this was asked before but in searches I only find how to use an external 1 PPS GPS signal for NTP synchronization. Having a Linux/FreeBSD PC synchronized using NTP/chrony, what would be the best way of generating an output 1 PPS signal on a (hardware) serial port ? For timing I've seen the standard libc functions from sys/time.h, like setitimer(), but maybe there are better ways for generating precise delays. ___ 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. ___ 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.
