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--- enable_pps_support_raspian [2019/11/03 09:20] – [Step 1: Download kernel] nikolal
+++ enable_pps_support_raspian [2022/09/19 11:34] (current) – external edit 127.0.0.1
@@ Line 3: / Line 3: @@
   * CONFIG_PPS ("PPS support" in "make menuconfig")
   * CONFIG_NTP_PPS ("PPS kernel consumer support" in "make menuconfig")
-===== Step 1: Download kernel =====
+==== Install dependencies ====
+''%%sudo apt install git bc bison flex libssl-dev%%''
+==== Download kernel ====
   mkdir ppskernel
   cd ppskernel
@@ Line 11: / Line 13: @@
   zcat /proc/config.gz > .config
   make oldconfig
+==== Configure kernel build options ====
 Then comes the hard part, setting the options. Normally this is straight forward, but due to some options only showing when others are disabled, it may be a little tricky.
-  make menuconfig
+  * Run ''%%make menuconfig%%''
-Go to ''%%General setup ---> Timers subsystem --->%%'' and disable ''%%Old Idle dynticks config%%'', then enter ''%%Timer tick handling%%'' and change it to ''%%Periodic timer ticks (constant rate, no dynticks)%%''
+  * Go to ''%%General setup ---> Timers subsystem --->%%'' and disable ''%%Old Idle dynticks config%%'', then enter ''%%Timer tick handling%%'' and change it to ''%%Periodic timer ticks (constant rate, no dynticks)%%''
-==== Turn on PPS support: ====
+  * Turn on PPS support: ''%%PPS kernel consumer support %%'' is the option that should have become visible after changing the timer settings. If not, save and reload ''%%make menuconfig%%''.
-    Device Drivers --->
+  * Enter Device Drivers ---> PPS support --->
-        PPS support --->
+\\
             <M> PPS support
             [ ]    PPS debugging messages
@@ Line 23: / Line 28: @@
                    *** PPS clients support ***
             < >    Kernel timer client (Testing client, use for debug)
-            < >    PPS line discipline
+            <M>    PPS line discipline
             <M>    PPS client using GPIO
                    *** PPS generators support ***
+\\
+  * Save and exit. To verify, check the ''%%.config%%'' file that has been created in the same folder (nano .config). These options should be present somewhere in the file:
+\\
+  CONFIG_PPS=y
+  CONFIG_NTP_PPS=y
+  #
+  # Timers subsystem
+  #
+  CONFIG_TICK_ONESHOT=y
+  CONFIG_HZ_PERIODIC=y
+  # CONFIG_NO_HZ_IDLE is not set
+  # CONFIG_NO_HZ_FULL is not set
+  # CONFIG_NO_HZ is not set
+  CONFIG_HIGH_RES_TIMERS=y
+  # CONFIG_PREEMPT_NONE is not set
+  CONFIG_PREEMPT_VOLUNTARY=y
+  # CONFIG_PREEMPT is not set
+==== Compile the kernel ====
+  make -j4
+  make modules
+\\
+  * Gain superuser privileges and transfer a copy of the new kernel to the boot partition:
+\\
+  sudo -i
+  cd ~pi/ppskernel/linux-rpi-[kernel version number].y
+  make modules_install
+  cp ./arch/arm/boot/zImage /boot/kernel_new.img
+\\
+  * Tell the system to use this new kernel by adding ''%%kernel=kernel_new.img%%'' to ''%%/boot/config.txt %%''.
+  * Reboot
+==== Add PPS source and load kernel module ====
+  * Open ''%%/boot/config.txt %%'' again, and ''%%dtoverlay=pps-gpio,gpiopin=[GPIOPIN]%%'' where GPIOPIN is the PPS signal.
+  * Load kernel module: ''%%sudo modprobe pps-gpio%%''
+==== Test  and make permanent====
+  * Test
+\\
+  apt-get install pps-tools
+  sudo ppstest /dev/pps0
+\\
+  * Expected result is something like:
+\\
+  trying PPS source "/dev/pps0"
+  found PPS source "/dev/pps0"
+  ok, found 1 source(s), now start fetching data...
+  source 0 - assert 1572772437.999997402, sequence: 6168 - clear  0.000000000, sequence: 0
+  source 0 - assert 1572772438.999997803, sequence: 6169 - clear  0.000000000, sequence: 0
+  source 0 - assert 1572772440.000000924, sequence: 6170 - clear  0.000000000, sequence: 0
+  source 0 - assert 1572772440.999998834, sequence: 6171 - clear  0.000000000, sequence: 0
+  source 0 - assert 1572772442.000001424, sequence: 6172 - clear  0.000000000, sequence: 0
+  source 0 - assert 1572772442.999999478, sequence: 6173 - clear  0.000000000, sequence: 0
+  source 0 - assert 1572772444.000000128, sequence: 6174 - clear  0.000000000, sequence: 0
+  source 0 - assert 1572772444.999999537, sequence: 6175 - clear  0.000000000, sequence: 0
+  source 0 - assert 1572772446.000000578, sequence: 6176 - clear  0.000000000, sequence: 0
+\\
+  * If successful, make permanent by opening ''%%/etc/modules%%'' and adding ''%%pps-gpio%%'' to the end.
+  * Running a DUNE configuration with ''%%Supervisors.ClockPPS%%'' should now work
 ===== Links =====
   * [[https://support.ntp.org/bin/view/Sandbox/HowtoPpsOnRaspberryPi|How to PPS on Raspberry Pi]]
+  * [[https://ava.upuaut.net/?p=951|5 minute guide to making a GPS Locked Stratum 1 NTP Server with a Raspberry Pi]]
+  * [[http://brandon.penglase.net/index.php?title=NavSpark_GPS%2BGLONASS_Stratum-1_NTP_Time_Source_with_a_Raspberry_Pi#Configure_the_kernel|NavSpark GPS+GLONASS Stratum-1 NTP Time Source with a Raspberry Pi]]
+  * [[https://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html|The Raspberry Pi as a Stratum-1 NTP Server]]