# MAVLINK Bridge ### Serial Connection Pixhawk TELEM2 is internally connected to the Jetson module. Let us first check the connection on the Jetson terminal. Consider having a MAV connection to companion computers in advance. Check [PX4 Docs](https://docs.px4.io/main/en/companion_computer/pixhawk_companion.html#serial-port-setup) for the details. For a sanity check, you could run[ mavlink shell](https://docs.px4.io/main/en/debug/mavlink_shell.html#mavlink-shell) on `/dev/ttyTHS0` ### Ethernet Connection Since there is no DHCP server active in this configuration, the IPs have to be set manually:\ Once the Ethernet cables are plugged in, the `eth0` network interface seems to switch from DOWN to UP. You can check the status using: ``` ip address show eth0 ``` You can also try to enable it manually: ``` sudo ip link set dev eth0 up ``` It then seems to automatically set a link-local address, for me it looks like this: ``` ip address show eth0 2: eth0: mtu 1500 qdisc mq state UP group default qlen 1000 link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff inet 169.254.21.183/16 brd 169.254.255.255 scope global noprefixroute eth0 valid_lft forever preferred_lft forever inet6 fe80::yyyy:yyyy:yyyy:yyyy/64 scope link valid_lft forever preferred_lft forever ``` This means the Jetson’s Ethernet IP is 169.254.21.183. #### IP setup on FC Now connect to the NuttX shell (using a console or the MAVLink shell) and check the status of the link: ``` ifconfig eth0 Link encap:Ethernet HWaddr xx:xx:xx:xx:xx:xx at DOWN inet addr:0.0.0.0 DRaddr:192.168.0.254 Mask:255.255.255.0 ``` For me, it is DOWN at first. To set it to UP: ``` ifup eth0 ifup eth0...OK ``` Now check the config again: ``` ifconfig eth0 Link encap:Ethernet HWaddr xx:xx:xx:xx:xx:xx at UP inet addr:0.0.0.0 DRaddr:192.168.0.254 Mask:255.255.255.0 ``` However, it doesn’t have an IP yet. I’m going to set one similar to the one of Jetson: ``` ifconfig eth0 169.254.21.184 ``` And check it: ``` ifconfig eth0 Link encap:Ethernet HWaddr xx:xx:xx:xx:xx:xx at UP inet addr:169.254.21.184 DRaddr:169.254.21.1 Mask:255.255.255.0 ``` Now the devices should be able to ping each other. Note that this configuration is ephemeral and will be lost after a reboot, so we’ll need to find a way to configure it statically. #### Ping test First from the Jetson terminal: ``` ping 169.254.21.184 PING 169.254.21.184 (169.254.21.184) 56(84) bytes of data. 64 bytes from 169.254.21.184: icmp_seq=1 ttl=64 time=0.188 ms 64 bytes from 169.254.21.184: icmp_seq=2 ttl=64 time=0.131 ms 64 bytes from 169.254.21.184: icmp_seq=3 ttl=64 time=0.190 ms 64 bytes from 169.254.21.184: icmp_seq=4 ttl=64 time=0.112 ms ^C --- 169.254.21.184 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3077ms rtt min/avg/max/mdev = 0.112/0.155/0.190/0.034 ms ``` And from the FC in Nuttx Shell: ``` ping 169.254.21.183 PING 169.254.21.183 56 bytes of data 56 bytes from 169.254.21.183: icmp_seq=0 time=0 ms 56 bytes from 169.254.21.183: icmp_seq=1 time=0 ms 56 bytes from 169.254.21.183: icmp_seq=2 time=0 ms 56 bytes from 169.254.21.183: icmp_seq=3 time=0 ms 56 bytes from 169.254.21.183: icmp_seq=4 time=0 ms 56 bytes from 169.254.21.183: icmp_seq=5 time=0 ms 56 bytes from 169.254.21.183: icmp_seq=6 time=0 ms 56 bytes from 169.254.21.183: icmp_seq=7 time=0 ms 56 bytes from 169.254.21.183: icmp_seq=8 time=0 ms 56 bytes from 169.254.21.183: icmp_seq=9 time=0 ms 10 packets transmitted, 10 received, 0% packet loss, time 10010 ms ``` #### MAVLink/MAVSDK test For this, we need to set the mavlink instance to send traffic to the Jetson’s IP: For an initial test we can do: ``` mavlink start -o 14540 -t 169.254.21.183 ``` This will send MAVLink traffic on UDP to port 14540 (the MAVSDK/MAVROS port) to that IP which means MAVSDK can just listen to any UDP arriving at that default port. To run a MAVSDK example, install mavsdk via pip, and try out an example from [MAVSDK-Python/examples](https://github.com/mavlink/MAVSDK-Python/tree/main/examples). For instance: ``` python3 -m pip install mavsdk wget https://raw.githubusercontent.com/mavlink/MAVSDK-Python/main/examples/tune.py chmod +x tune.py ./tune.py ```