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JM
Aug 4, 2014, 5:44:16 PM8/4/14
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I am setting up an NTP server using a BBB and an NMEA-compatible GPS device. I have wired up the GPS serial port to UART5 and the GPS 1 PPS output to both a GPIO pin and UART5_CTS. I have successfully configured everything to use kernel-level events for the 1 PPS via the GPIO pin, but not via the CTS pin. GPSD can see that the CTS line is toggling, but since the kernel is not detecting these events, GPSD falls back to a less accurate measurement.
Syslog messages showing PPS registration:
Syslog messages showing GPSD using less accurate PPS measurement instead of KPPS:
NTP syncing to GPIO PPS (127.127.22.0), not GPSD/CTS PPS (127.127.28.1):
Question: What are the necessary settings to make UART5_CTS generate kernel PPS events?
Thanks in advance for any assistance.
RCN kernel Linux bb-sdcard 3.8.13-bone59 #1 SMP Sat Jul 5 02:59:43 UTC 2014 armv7l armv7l armv7l GNU/Linux
NTPD version 4.2.7p454
GPSD version 3.10
Relevant DTS sections:
fragment@40 {
target = <&am33xx_pinmux>;
__overlay__ {
pinctrl_pps: pinctrl_pps_pins {
pinctrl-single,pins = <
0x0C8 0x27 // P8.36 uart3_cts INPUT PULLDN MODE7
>;
};
};
};
fragment@41 {
target = <&am33xx_pinmux>;
__overlay__ {
pinctrl_uart5: pinctrl_uart5_pins {
pinctrl-single,pins = <
0x0D8 0x36 // P8.31 uart5_cts INPUT PULLUP MODE6
//0x0DC 0x16 // P8.32 uart5_rts OUTPUT PULLUP MODE6
0x0C0 0x04 // P8.37 uart5_txd OUTPUT PULLDN MODE4
0x0C4 0x24 // P8.38 uart5_rxd INPUT PULLDN MODE4
>;
};
};
};
fragment@42 {
target = <&ocp>; __overlay__ {
#address-cells = <1>;
#size-cells = <1>;
pps {
compatible = "pps-gpio";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_pps>;
status = "okay";
gpios = <&gpio3 16 0>; // Linux GPIO enumeration is +1 from chip number
assert-rising-edge;
};
};
};
fragment@43 {
target = <&uart6>; //Linux enumeration is +1 from chip number
__overlay__ {
status = "okay";
};
};
fragment@44 {
target = <&ocp>;
__overlay__ {
uart5_helper {
compatible = "bone-pinmux-helper";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_uart5>;
status = "okay";
};
};
};
Syslog messages showing PPS registration:
Aug 4 20:42:37 bb-sdcard kernel: [ 0.141178] pps_core: LinuxPPS API ver. 1 registeredAug 4 20:42:37 bb-sdcard kernel: [ 0.141187] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giom...@linux.it>Aug 4 20:42:37 bb-sdcard kernel: [ 2.043004] pps_ldisc: PPS line discipline registeredAug 4 20:42:49 bb-sdcard kernel: [ 22.804952] pps pps0: new PPS source pps.15.-1Aug 4 20:42:49 bb-sdcard kernel: [ 22.805089] pps pps0: Registered IRQ 208 as PPS sourceAug 4 20:42:51 bb-sdcard kernel: [ 23.984672] pps pps1: new PPS source OMAP-SERIAL5Aug 4 20:42:51 bb-sdcard kernel: [ 23.984766] pps pps1: source "/dev/ttyO5" addedActual PPS devices, note pps0 generating kernel events and pps1 not:
root@bb-sdcard# ll /sys/class/pps/*lrwxrwxrwx 1 root root 0 Aug 4 20:42 /sys/class/pps/pps0 -> ../../devices/virtual/pps/pps0/lrwxrwxrwx 1 root root 0 Aug 4 20:42 /sys/class/pps/pps1 -> ../../devices/virtual/pps/pps1/root@bb-sdcard# cat /sys/class/pps/pps0/assert1407188062.999944873#3094root@bb-sdcard# cat /sys/class/pps/pps1/assert0.000000000#0
Aug 4 20:42:13 bb-sdcard gpsd[1363]: gpsd:PROG: KPPS assert 0.000000000, sequence: 0 - clear 0.000000000, sequence: 0Aug 4 20:42:13 bb-sdcard gpsd[1363]: gpsd:PROG: KPPS data: using clearAug 4 20:42:13 bb-sdcard gpsd[1363]: gpsd:PROG: KPPS cycle: 0 uSec, duration: 0 uSec @ 0.000000000Aug 4 20:42:13 bb-sdcard gpsd[1363]: gpsd:RAW: PPS pps-detect on /dev/ttyO5 changed to 1Aug 4 20:42:13 bb-sdcard gpsd[1363]: gpsd:PROG: PPS cycle: 1000050 uSec, duration: 199995 uSec @ 1407184933.203313318Aug 4 20:42:13 bb-sdcard gpsd[1363]: gpsd:RAW: PPS edge rejected 1Hz trailing edgeAug 4 20:42:14 bb-sdcard gpsd[1363]: gpsd:PROG: KPPS assert 0.000000000, sequence: 0 - clear 0.000000000, sequence: 0Aug 4 20:42:14 bb-sdcard gpsd[1363]: gpsd:PROG: KPPS data: using clearAug 4 20:42:14 bb-sdcard gpsd[1363]: gpsd:PROG: KPPS cycle: 0 uSec, duration: 0 uSec @ 0.000000000Aug 4 20:42:14 bb-sdcard gpsd[1363]: gpsd:RAW: PPS pps-detect on /dev/ttyO5 changed to 0Aug 4 20:42:14 bb-sdcard gpsd[1363]: gpsd:PROG: PPS cycle: 999973 uSec, duration: 799977 uSec @ 1407184934.003291184Aug 4 20:42:14 bb-sdcard gpsd[1363]: gpsd:RAW: PPS edge accepted 1Hz leading edgeAug 4 20:42:14 bb-sdcard gpsd[1363]: gpsd:RAW: PPS ntpshm_put 1407184934.000000000 @ 1407184934.003291184Aug 4 20:42:14 bb-sdcard gpsd[1363]: gpsd:INFO: PPS hooks called with accepted 1407184934.003291184 offset -0.003291184Aug 4 20:42:14 bb-sdcard gpsd[1363]: gpsd:PROG: PPS edge accepted 1407184934.003291184 offset -0.003291184NTP syncing to GPIO PPS (127.127.22.0), not GPSD/CTS PPS (127.127.28.1):
root@bb-sdcard# ntpq -crv -pnassocid=0 status=011d leap_none, sync_pps, 1 event, kern,version="ntpd 4.2....@1.2483 Thu Jul 31 18:42:54 UTC 2014 (2)",processor="armv7l", system="Linux/3.8.13-bone59", leap=00, stratum=1,precision=-19, rootdelay=0.000, rootdisp=1.165, refid=PPS,reftime=d78a7b8f.133c7be8 Mon, Aug 4 2014 21:37:19.075,clock=d78a7b9a.98131c27 Mon, Aug 4 2014 21:37:30.594, peer=21917, tc=4,mintc=3, offset=-0.005, frequency=-27.669, sys_jitter=0.007313,clk_jitter=0.000, clk_wander=0.001 remote refid st t when poll reach delay offset jitter============================================================================== 127.127.28.0 .GPS. 0 l 11 16 377 0.000 -1.311 0.111 127.127.28.1 .PPS. 0 l 11 16 377 0.000 -0.095 0.007o127.127.22.0 .PPS. 0 l 11 16 377 0.000 -0.005 0.007*172.16.15.100 .GPS. 1 u 37 64 377 7.644 -0.045 0.420-50.7.0.66 128.138.141.172 2 u 30 64 377 35.170 -6.805 5.060+204.235.61.9 128.10.19.24 2 u 34 64 377 44.352 -1.701 1.732+206.217.199.65 204.9.54.119 2 u 32 64 177 35.892 -2.374 3.846-96.226.242.15 204.9.54.119 2 u 9 64 77 14.801 2.163 1.655
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