Network setup

Back to Robobot B

WiFi network

Network Manager

The NetworkManager uses device UUID as part of the Wi-Fi network setup. This means that (sometimes) an SD card can not be moved from one robot to another with a functional Wi-Fi connection.

After 20 seconds, an attempt to solve this is activated using the commands below (the code is found in svn/robobot/setup/rename_host.bash - last half).

Use the last line to setup manually - or the GUI, if available.

Network manager connection with UUID

nmcli connection

List available wifi access points

nmcli dev wifi

Connect to DTUdevice net

sudo nmcli device wifi connect DTUdevice password <password> ifname wlan0

This should create a new system-connection file with a usable UUID

Local link connection

If wifi is too slow or not available, then a local link using a network cable could be the solution.

Many PCs with assign a local link IP like 168.254.x.x and the Robot will do the same. The robot IP will be displayed on the small display, but may be obscured, if a wifi IP is available too.

To prepare, log-in to the raspberry using wifi (or attach screen and keyboard) and make a preferred local-link connection:

sudo nmcli con "Wired connection 1" ipv4.method local-link ipv6.method auto

This will

Check IP and SSID

When the Pi has rebooted, connect to it using SSH once again. Check that the Pi is connected to WiFi

ifconfig

Under wlan0 confirm that the Pi has received an IP (inet addr) and note down the first three sections of the IP - they are most likely 10.197.21x.xxx

To see which SSID you are connected to, use

iwconfig

or

nmcli -o

The MAC address ('HWaddr' or 'ether') of the Pi should also be noted down - this probably starts with B8:27:EB:xx:xx:xx make sure to get all of it.

Find IP of robot (Linux)

In case the Pi gets a new IP address after reboot, you can search for it using the MAC address and nmap. If nmap is not installed, start by installing it

sudo apt-get install nmap

To search for the Pi using the MAC address in terminal type

nmap -sP 10.197.218.0/20 | awk '/^Nmap/{ip=$NF}/B8:27:EB:23:A0:F5/{print ip}'

where 10.197.218 is the first three sections of the IP you noted down, 20 is the number of fixed bits (out of 32), and B8:27:EB:23:A0:F5 is the MAC address of the Pi. This should return the IP of the Pi.

NB! the MAC can hold letters, they should probably be capital.

If you don't know the IP address

Use the first part to get a list of active IPs on the net:

 nmap -sP 10.197.218.0/24

The robot's name should be included in the list, but the network may take a while to detect it.

NTP

Network Time Protocol is used to keep clocks in sync. Raspberry Pi will start with the date and time of the last proper shutdown, and some seconds after the internet is up, it will sync the clock using NTP.

At DTU most clock sources are blocked, the clock source needs to be configured.

At DTU, edit /etc/NTP.conf or /etc/ntpsec/ntp.conf and add ntp.ait.du.dk to the top of the server pool list.

sudo nano /etc/ntpsec/ntp.conf

...
# Use servers from the NTP Pool Project. Approved by Ubuntu Technical Board
# on 2011-02-08 (LP: #104525). See http://www.pool.ntp.org/join.html for
# more information.
pool ntp.ait.dtu.dk
...

Sync time (if on DTU net)

sudo ntpdate -u ntp.ait.dtu.dk

Should work in and around DTU - see also NTP howto for more details.