From Brandon's Tinkerings
Jump to: navigation, search
(Random Notes (The building blocks))
(Random Notes (The building blocks))
Line 88: Line 88:
  
 
apt-get install pps-tools snmp libcap-dev i2c-tools
 
apt-get install pps-tools snmp libcap-dev i2c-tools
 +
 +
edit /boot/config.txt: add --
 +
 +
dtoverlay=pps-gpio,gpiopin=<x>
 +
 +
Custom PCB uses GPIO23
 +
 +
======================================================================
 +
OLD/INVALID
  
 
edit /boot/cmdline.txt, remove serial references (AMA0) (only needed if you don't select to turn off serial console above)
 
edit /boot/cmdline.txt, remove serial references (AMA0) (only needed if you don't select to turn off serial console above)
  
 
edit /etc/inittab, remove serial console (only needed if you don't select to turn off serial console above)
 
edit /etc/inittab, remove serial console (only needed if you don't select to turn off serial console above)
 +
  
 
KERNEL TIME
 
KERNEL TIME
Line 171: Line 181:
 
kernel=Image-3187
 
kernel=Image-3187
  
dtoverlay=pps-gpio,gpiopin=<x>
 
  
Custom PCB uses GPIO23
+
 
 +
=============================================================================================
  
 
Grab latest NTP from: http://www.ntp.org/downloads.html, for compile computer
 
Grab latest NTP from: http://www.ntp.org/downloads.html, for compile computer
Line 279: Line 289:
 
dpkg --purge fake-hwclock
 
dpkg --purge fake-hwclock
  
cd /etc/rcS.d
+
##cd /etc/rcS.d
  
 
update-rc.d hwclock.sh enable
 
update-rc.d hwclock.sh enable

Revision as of 16:40, 19 February 2015

Intro

Here are my notes for getting a NavSpark GPS+GLONASS module working with a Raspberry Pi (Model B) for Timing/NTP purposes. They have since come out with a specific timing module that would probably be better suited for this. But alas, it's not what I have right now :)

What is this all about?

For a long time now, I've wanted to setup a Stratum 1 time source. It allows better matching of logs for debugging, and allows a more accurate time source for local network devices.

This page goes over the module, getting it wired up to a Pi, then getting the Pi working with the module. I've also added a i2c TCXO RTC (DS3231) for timekeeping while the unit does not have power. This was added as the Pi does not have an RTC built in, and it may take some time for the Pi to sync with peers and/or GPS to get time set.

This will give me a time source on my network that is extremely accurate for my needs.

I created a custom PCB for attaching the NavSpark module, DS3231, and associated parts to the Pi. This makes it nice and compact to put to the side to just run. Gives it a nice SAF. (Spouse Approval Factor)

What does this page assume?

  • You have a NavSpark (or similar) GPS Module that outputs RS232 TTL NEMA GPS code, as well as a 1PPS (Pulse per second) output.
  • You have a Raspberry Pi (B or B+ preferred, since it has the wired network interface already on it)
  • You know how to wire/breadboard stuff to the Pi
  • Fresh install of Raspbian (either directly or through NOOBS)

Other

  • Logic Level Converter - If your GPS module outputs 5v, as the Pi need 3v in. (Note: The NavSpark outputs 3v)
  • Solder
  • Soldering Iron
  • Materials in BOM below if using custom adapter board
  • Pi Case
  • Good, solid/stable output, 5v USB Power Supply (a good quality power supply can make a big difference, especially when used in timing situations)
  • Setting up a cross-compile environment
  • Comfortable compiling and installing software/kernel
  • Comfortable applying patches

My Testing Environment

DevSetup.jpg



The Code

Caveats

Resources Used to Complete this

Fin

Random Notes (The building blocks)

http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html

set user password

Advanced options

-set hostname - NTP1

-Change GPU memory to 16M (not used for NTP, more memory available to the system)

-Enable Kernel i2c

-Disable Kernel/Shell over Serial

finish, reboot.

login as pi

sudo -s

set root password

Update Pi

apt-get update

apt-get dist-upgrade

rpi-update

reboot

apt-get install pps-tools snmp libcap-dev i2c-tools

edit /boot/config.txt: add --

dtoverlay=pps-gpio,gpiopin=<x>

Custom PCB uses GPIO23

==========================================================

OLD/INVALID

edit /boot/cmdline.txt, remove serial references (AMA0) (only needed if you don't select to turn off serial console above)

edit /etc/inittab, remove serial console (only needed if you don't select to turn off serial console above)


KERNEL TIME

Build Machine

crossdev -S -v -t arm-unknown-linux-gnueabi

Recommend to compile kernel on another system --http://elinux.org/Raspberry_Pi_Kernel_Compilation

export CCPREFIX=arm-unknown-linux-gnueabi-

may need gcc-config to set current version if updated

get kernel source: git clone --depth 1 git://github.com/raspberrypi/linux.git pikern

grab default /proc/config.gz from Pi, uncompress and copy to pikern/.config

make ARCH=arm CROSS_COMPILE=${CCPREFIX} oldconfig

modify kernelmake ARCH=arm CROSS_COMPILE=${CCPREFIX} menuconfig

(Required!)General -> Default Hostname (NTP1)

General -> Timers Subsystem -> Timer Tick Handling (Idle Dynticks System (Tickless Idle)) -> Periodic Timer Ticks (Constant rate, no dynticks) -- This is needed for NTP_PPSGeneral

-> Deselect "Old Idle Dynticks Config"

Boot Options -> Default Kernel Command -> Remove "console=ttyAMA0,115200"

Device Drivers -> PPS Support (*)-> (*) PPS Kernel Consumer Support (Will not show up if the timer subsystem options above are not set)

-> (*) PPS Client using GPIO

Device Drivers -> Real Time Clock -> (*) Dallas/Maxim DS1307/37/38/39/40, ST M41T00, EPSon RX-8025 (For RTC 3231 option below)

(Optional)Kernel Features -> memory split -> 2G/2G

Preemption Model -> No forced preemption (Server)

CPU Power Management -> CPU Frequency Scaling -> Default CPU Freq Governor -> Performance

OldKernel

Patch Kernel: http://ntpi.openchaos.org/pps_pi/ - https://raw.githubusercontent.com/lampeh/rpi-misc/master/linux-pps/linux-rpi-pps-gpio-bcm2708.diff

Note: Line numbers are different with newer kernel. Provide updated patch....

NewKernel

>=3.18.x?

Use DeviceTable - No patching

make ARCH=arm CROSS_COMPILE=${CCPREFIX} -j4

mkdir modtmp

make ARCH=arm CROSS_COMPILE=${CCPREFIX} INSTALL_MOD_PATH=./modtmp modules_install

tar -cjf modules.tar.bz2 modtmp/

scp modules.tar.bz2 root@ntp1:~/

scp arch/arm/boot/Image root@10.0.3.14:/boot/Image-31229

tar -xjf modules.tar.bz2

mv /lib/modules/<version> /lib/modules/<version>-orig

mv modtmp/lib/modules/<version> /lib/modules

cp -R modtmp/lib/firmware/* /lib/firmware

edit /boot/config.txt

add:

kernel=Image-3187


=================================================================================

Grab latest NTP from: http://www.ntp.org/downloads.html, for compile computer

extract

./configure --prefix=/usr --enable-ATOM --enable-NMEA --enable-GPSD --enable-SHM --enable-WWV --with-ntpsnmpd --enable-ipv6 --enable-linuxcaps --enable-clockctl

make

now wait ~20minutes

rm /var/lib/ntp/ntp.conf.dhcp if DHCP, static recommended

    1. Cross-compile NTP:
    1. mkdir tmpinstall##make -j2##make install
    1. tar -cjf ntp.tar.bz2 tmpinstall
    1. copy files out cp bin/ntpd bin/ntp-wait bin/ntptime /usr/sbin
    1. https://support.ntp.org/bin/view/Dev/Cross-compilingNTP

create /etc/udev/rules/09-gps.rules

file contents:

  1. Adds symlink from serial interface to /dev/gps0 for ntpd

KERNEL=="ttyAMA0", SYMLINK+="gps0"

Edit /etc/ntp.conf

enable calibrate

enable kernel

  1. GPS Module

server 127.127.20.0 mode 82 minpoll 4 maxpoll 6

fudge 127.127.20.0 time2 +0.1939

  1. PPS of GPS Module

server 127.127.22.0 minpoll 4

fudge 127.127.22.0 flag3 1

Add other servers/peers, set one as prefer (needed to get PPS lock, see http://ntpi.openchaos.org/pps_pi/)

Tune the offset http://www.catb.org/gpsd/gpsd-time-service-howto.html

    1. RTC

modules/i2c already enabled in kernel from above

i2c-dev module

i2cdetect -y 1 - verify on 68

echo "ds3231 0x68" > /sys/class/i2c-adapter/i2c-1/new_device

set timezone -

rm /etc/localtime

ln -s /usr/share/zoneinfo/America/New_York /etc/localtime

edit /etc/default/hwclock

HWCLOCKACCESS=YES

HCTOSYS_DEVICE=rtc0

edit /etc/init.d/hwclock.sh, line 64, comment out if statement for udev

The RTC isn't handled by udev, so this check needs to be removed.

Add after unset TZ in hwclock.sh

modprobe i2c-bcm2708

modprobe i2c-dev

modprobe rtc-ds1307

echo "ds3231 0x68" > /sys/class/i2c-adapter/i2c-1/new_device

  1. Static IP

Edit /etc/networking/interfaces

iface eth0 inet static

address

netmask

gateway

  1. http://www.raspberrypi.org/forums/viewtopic.php?f=44&t=16218

dpkg --purge fake-hwclock

    1. cd /etc/rcS.d

update-rc.d hwclock.sh enable

update-rc.d alsa-utils disable

update-rc.d x11-common disable

    1. OLD

apt-get install gpsd gpsd-clients python-gps

edit /etc/defaults/gpsd

start_daemon = true

devices="/dev/ttyAMA0"

flags -b -n

stty -F /dev/ttyAMA0 115200

set base_baud before gpsd starts, scans faster.

service gpsd enable

reboot, confirm with cgps -s

apt-get install libncurses5-dev bc

edit modules, include pps-gpio

Instead of gpsd - symlink /dev/ttyAMA0 to /dev/gps0, use 127.127.20.0 mode 82 in ntp config, adds GPS_NEMA driver

Uninstall existing ntp, compile/install latest ntp