update readme

README.md

@@ -13,6 +13,8 @@ ROS package that interfaces the time synchronization chrony daemon and provide s
 6. This should work and you can start the daemon with gpsd to see if it is installed successfully.
 7.  Official tutorial [here](https://gpsd.gitlab.io/gpsd/building.html) if you got any problems.
 
+need to modify python version to install GPSD (TODO : give how later)
+
 ### Installation of Chrony
 
 1. Download lastest release of chrony [here](https://chrony.tuxfamily.org/download.html)
@@ -62,6 +64,37 @@ To check if it's working do : `chronyc sources -v` (-v is useful to understand s
 You should have something like : `#- GPS or #+ GPS` and under `#* PPS`
 If you have those sign, sources are synchronized.
 
+## other and tips
+
+You have to change your GPS configuration to emit pps
+(TODO : ADD how on ublox later)
+
+see sync of chrony :
+```
+chronyc tracking
+```
+see gps data :
+```
+gpsd -n /dev/tty...
+ntpd -gN
+cgps
+```
+rerun services :
+```
+sudo systemctl restart chrony
+sudo systemctl restart gpsd
+```
+PS :
+
+make sure to uninstall ntp (ntp install will uninstall chrony)
+
+lib use :
+
+* gpsd
+* ntpd
+* cgps
+* chrony
+
 ## Authors and acknowledgment
 
 Corentin Boulongne & Gérald Dherbomez