Dear Sir, I am trying to synchronize AM335x processor based linux 3.2 with Motorola GPS receiver using its Serial based NMEA frame and 1pps signal. I have connected nmea frame to ttyO1 port. I am using buildroot based filesystem for NTP configuration. NTP version used is 4.2.6p5.
I have configured ntp.conf file for nmea driver 20 for nmea and 1pps options. (refer: http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html) # Ajay - for nmea driver 20 server 127.127.20.0 mode 0 minpoll 4 maxpoll 4 prefer fudge 127.127.20.0 flag1 1 flag2 0 flag3 1 time2 0.500. time2 is set to 0.600 since delay between 1pps signal rising edge and end of nmea frame is approx 500ms. i am issuing below command for nmea driver 20 before starting ntp service: ldattach pps /dev/ttyO1. [ 94.658905] pps_core: source OMAP-SERIAL1 got cdev (253:0) [ 94.658935] pps pps0: new PPS source OMAP-SERIAL1 [ 94.663787] pps pps0: source "/dev/ttyO1" added Also, while kernel booted it already had registered pps for kernel line discopline as per below message: [ 0.181427] pps_core: LinuxPPS API ver. 1 registered [ 0.181427] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giome...@linux.it> ln -s /dev/ttyO1 /dev/gps0 (for linking ttyO1 to /dev/gps0 for nmea driver 20) (as per http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html) and ln -s /dev/pps0 /dev/gpspps0 (for linking pps0 to /dev/gpspps0 for nmea driver 20) (as per http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html) Now, when i start the ntp service, i get below output for ntpq -p command: remote refid st t when poll reach delay offset jitter ============================================================================== *GPS_NMEA(0) .GPS. 0 l 4 16 377 0.000 4526.86 1269.17 Problem: Though i have configured my ntp.conf file for nmea and 1pps both (using flag1 1), i do not see any entry for PPS in ntpq -p command. if kernel has registered pps0 as pps source, why there is not PPS entry. I have connected pps signal of 3.3v level to my dcd pin of ttyO1. Also, the offset in NMEA output continously increases insteed of reducing. Thanks & Regards, Ajay _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
