1. 前言
承接上篇 https://www.ebaina.com/articles/140000012552
2. agx平台正常工作如下将此文件保存为/boot/pps.dts
/dts-v1/; /plugin/; / { overlay-name = “Jetson PPS”; compatible = “nvidia,p3509-0000+p3668-0001”; fragment { target-path = “/”; __overlay__ { pps: pps_gpio { compatible = “pps-gpio”; gpios = <&tegra_main_gpio 148 1>; assert-falling-edge; status = “okay”; }; }; }; };将gpio更改为GPIO09，这是40引脚头上的第7引脚，因为GPS帽我已经将PPS信号硬线到那个引脚。 将dts编译成dtb
cd /boot $ sudo dtc -I dts -O dtb -@ -o pps.dtbo pps.dts从库存dtb和pps.dtbo创建一个自定义dtb
sudo fdtoverlay -i tegra194-p3668-all-p3509-0000.dtb -o tegra194-p3668-all-p3509-0000-user-custom.dtb tegra194-p3668-all-p3509-0000-hdr40.dtbo pps.dtbo现在编辑/boot/extlinux/extlinux.conf， 并将以下行添加到菜单项中…
LINUX … INITRD … FDT /boot/tegra194-p3668-all-p3509-0000-user-custom.dtb APPEND …现在重新启动。 当系统恢复运行时，应该有一个/dev/pps0设备。 将PPS源代码连接到pin 7并安装了PPS -tools包， 应该能够运行
$ sudo ppstest /dev/pps0 trying PPS source “pps0” found PPS source “pps0” ok, found 1 source(s), now start fetching data… source 0 – assert 1592529430.097600543, sequence: 2333 – clear 0.000000000, sequence: 0 source 0 – assert 1592529431.097604009, sequence: 2334 – clear 0.000000000, sequence: 0 source 0 – assert 1592529432.097600339, sequence: 2335 – clear 0.000000000, sequence: 0 source 0 – assert 1592529433.097601277, sequence: 2336 – clear 0.000000000, sequence: 0下一步取决于希望如何同步内核时间， 以便ptpd可以发送内核时间 我用ntpd取两个源 第一个是可靠的上游ntp服务器 第二个是通用的nmea源，它接受来自gps单元的nmea句子和pps信号 一旦内核被同步，ptpd就可以被设置为主服务器
3.将sdcard安装到另一个设备上 /media/boot$ ls dtb tegra186-quill-p3310-1000-c03-00-base-hdr40.dtbo extlinux tegra186-quill-p3310-1000-c03-00-dsi-hdmi-dp.dtb grub tegra186-quill-p3489-0888-a00-00-base.dtb Image tegra186-quill-p3489-1000-a00-00-ucm1.dtb Image.sig tegra186-quill-p3489-1000-a00-00-ucm2.dtb initrd tegra194-p2888-0001-p2822-0000-adafruit-sph0645lm4h.dtbo initrd.img tegra194-p2888-0001-p2822-0000.dtb initrd.img-4.9.140-tegra tegra194-p2888-0001-p2822-0000-fe-pi-audio-z-v2.dtbo pps.dtbo tegra194-p2888-0001-p2822-0000-hdr40.dtbo pps.dts tegra194-p2888-0001-p2822-0000-maxn.dtb tegra186-quill-p3310-1000-a00-00-base.dtb tegra194-p3668-all-p3509-0000-adafruit-sph0645lm4h.dtbo tegra186-quill-p3310-1000-as-0888.dtb tegra194-p3668-all-p3509-0000.dtb tegra186-quill-p3310-1000-c03-00-base-adafruit-sph0645lm4h.dtbo tegra194-p3668-all-p3509-0000-fe-pi-audio-z-v2.dtbo tegra186-quill-p3310-1000-c03-00-base.dtb tegra194-p3668-all-p3509-0000-hdr40.dtbo tegra186-quill-p3310-1000-c03-00-base-fe-pi-audio-z-v2.dtbo tegra194-p3668-all-p3509-0000-user-custom.dtb xavier@agx:/media/boot$ cat extlinux/extlinux.conf TIMEOUT 30 DEFAULT primary MENU TITLE L4T boot options LABEL primary MENU LABEL primary kernel LINUX /boot/Image INITRD /boot/initrd FDT /boot/tegra194-p3668-all-p3509-0000-user-custom.dtb APPEND ${cbootargs} quiet # When testing a custom kernel, it is recommended that you create a backup of # the original kernel and add a new entry to this file so that the device can # fallback to the original kernel. To do this: # # 1, Make a backup of the original kernel # sudo cp /boot/Image /boot/Image.backup # # 2, Copy your custom kernel into /boot/Image # # 3, Uncomment below menu setting lines for the original kernel # # 4, Reboot # LABEL backup # MENU LABEL backup kernel # LINUX /boot/Image.backup # INITRD /boot/initrd # APPEND ${cbootargs}<
检查文件系统和日志不会提供任何提示。
cat pps.dts /dts-v1/; /plugin/; / { overlay-name = “Jetson PPS”; compatible = “nvidia,p3509-0000+p3668-0001”; fragment { target-path = “/”; __overlay__ { pps: pps_gpio { compatible = “pps-gpio”; gpios = <&tegra_main_gpio 148 1>; assert-falling-edge; status = “okay”; }; }; }; }; 4. 按照上述步骤运行 sudo /opt/nvidia/jetson-io/config-by-hardware.py -l Configurations for the following hardware modules are available: 1. Adafruit SPH0645LM4H 2. FE-PI Audio Z V2 3. Jetson PPS ** ** sudo /opt/nvidia/jetson-io/config-by-hardware.py -n “Jetson PPS” Configuration saved to /boot/tegra194-p3668-all-p3509-0000-jetson-pps.dtb. then Reboot. Then ls /dev/pp ppp pps0 $ sudo ppstest /dev/pps0 trying PPS source “/dev/pps0” found PPS source “/dev/pps0” ok, found 1 source(s), now start fetching data… time_pps_fetch() error -1 (Connection timed out) time_pps_fetch() error -1 (Connection timed out).是否需要把时间脉冲线连接到7号引脚上？ 否则将不会启动
5. 如何将pps0输出转发到linuxptp从硬件的角度来看，是否需要从PPS源连接一根线? 引脚N7?PPS来源的两根电线? 引脚N7和其他一些引脚?
肯定是需要物理连接的
我所做的是将GPS的PPS输出连接到脚7 GPS的TXD连接到脚10 GPS的RXD连接到脚8 这允许ntpd从gps获取NMEA语句来设置日期和时间，而PPS则同步秒数。 以下udev规则将创建正确的/dev符号链接
KERNEL==”ttyTHS0″, SYMLINK+=”gps0″ KERNEL==”pps0″, MODE=”0660″, SYMLINK+=”gpspps0″“`c KERNEL==”ttyTHS0″, SYMLINK+=”gps0″ KERNEL==”pps0″, MODE=”0660″, SYMLINK+=”gpspps0″conf中的这些条目将告诉ntpd同时使用NMEA语句和PPS…
server 127.127.20.0 mode 80 minpoll 3 burst iburst prefer fudge 127.127.20.0 stratum 1 flag1 1 flag2 0 flag3 1 flag4 0 time1 0.0 time2 0.095 refid GPP0需要对time2值进行一点调整(参见ntp文档)
ntpq -p remote refid st t when poll reach delay offset jitter ============================================================================== 0.ubuntu.pool.n .POOL. 16 p – 64 0 0.000 0.000 0.000 1.ubuntu.pool.n .POOL. 16 p – 64 0 0.000 0.000 0.000 2.ubuntu.pool.n .POOL. 16 p – 64 0 0.000 0.000 0.000 3.ubuntu.pool.n .POOL. 16 p – 64 0 0.000 0.000 0.000 ntp.ubuntu.com .POOL. 16 p – 64 0 0.000 0.000 0.000 GPS_NMEA(0) .GPP0. 1 l – 8 0 0.000 0.000 0.000 +time.nullrouten 132.163.97.1 2 u 11 64 1 78.194 0.584 1.964 +159.203.82.102 225.254.30.190 4 u 12 64 1 13.616 0.098 1.958 #time.gac.edu 127.67.113.92 2 u 12 64 1 44.552 -1.930 1.933 +atl0.jane.mattn 159.203.158.197 3 u 11 64 1 27.501 0.242 2.295 +mirror1.sjc02.s 216.218.254.202 2 u 9 64 1 82.024 2.156 3.990 +50-205-244-109- 50.205.244.28 2 u 10 64 1 30.418 2.101 2.553 +undef.us 198.82.247.51 3 u 8 64 1 41.361 1.437 2.649 +dev.smatwebdesi 204.9.54.119 2 u 10 64 1 46.248 1.869 2.544 +srcf-ntp.stanfo 171.64.7.105 2 u 8 64 1 80.683 0.557 2.083 alphyn.canonica 132.163.97.1 2 u 16 64 1 4.576 -2.268 0.000 +cmpublishers.co 209.51.161.238 2 u 10 64 1 27.733 0.665 3.785 #li290-38.member 199.102.46.72 2 u 7 64 1 46.609 -3.801 3.020 +LAX.CALTICK.NET 72.29.161.5 2 u 7 64 1 70.200 2.860 2.647 +199.102.46.79 ( .GPS. 1 u 6 64 1 34.969 0.075 1.991 *ntp2.wiktel.com .GPS. 1 u 7 64 1 46.731 1.271 2.434 golem.canonical 145.238.203.14 2 u 16 64 1 77.500 -1.331 0.000<
似乎不起作用
dev/gps0和/dev/gpspps0是否存在，是否分别链接到/dev/ttyTHS0和/dev/pps0 ? 是否能看到来自/dev/ttyTHS0的NMEA句子吗? ppstest /dev/pps0是否显示事件?
ls /dev/gps gps0 gpspps0 cat /dev/ttyTHS0 stty < /dev/ttyTHS0 speed 115200 baud; line = 0; intr = <undef>; quit = <undef>; erase = <undef>; kill = <undef>; eof = <undef>; start = <undef>; stop = <undef>; susp = <undef>; rprnt = <undef>; werase = <undef>; lnext = <undef>; discard = <undef>; ignbrk -brkint -imaxbel -opost -onlcr -isig -iexten -echo -echoe -echok -echoctl -echoke 6.ntp软件问题Ubuntu 18的ntpd版本有一个问题。 可能需要获取最新的ntp源并编译自己的ntp源。
