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Networking functions


connman connects wifi and ethernet (SMSC9514 USB 4p+LAN hub) or ethernet-over-usb (gadget).

You might need to systemctl enable connman && systemctl start connman once.


SMSC LAN9514 4p usb/ethernet hub works without configuration. But you can turn it off with connmanctl.

disable ethernet  


It may be soft blocked. To unblock use connmanctl.

enable wifi
agent on 
enable wifi
scan wifi
connect wifi_12345678_123......910_managed_psk

and enter your password

The following method to unblock works but I consider this obsolete:

root@edison:~# rfkill list

0: phy0: wlan
        Soft blocked: yes
        Hard blocked: no
root@edison:~# rfkill unblock 0
root@edison:~# rfkill list
0: phy0: wlan
        Soft blocked: no
        Hard blocked: no

To unblock wifi and bluetooth simultaneously:

    rfkill unblock all

Wifi tethering

The current version of connmanctl take care of tethering without the use of hostapd. Therefore we removed hostapd. Instructions for enabling a wifi access point:

enable wifi
tether wifi on <ssid> <passphrase with at least 8 chars>

To quickly switch between Access Point and Wifi:

ap-mode-toggle start | stop | status | toggle

You must have manually setup a tether previously using connmanctl, the stored ssid and passphrase will be used.


It may be powered off. To power on use connmanctl.

enable gadget
connect gadget_aabbccddeef1_usb

To make a shared network you need to configure the host computer. On KDE5 (Kubuntu 18.10) create a new connection using Plasma Network Manager:

Make a new network connection

Make this network active only on the shared network device:

Restrict to Edison only

Select shared with other computers:

Make the connection shared

Other network manager based desktops will require similar steps.


Create a directory /var/lib/connman-vpn/ containing your myhost.config file. myhost can be whatever you like, the extension must be .config. If you have a working openvpn connection (f.i. on your desktop) you already have working certificate files. Place them under /etc/openvpn/.

Sample myhost.config

Type = OpenVPN
Name = MyHost
Host = my.host.com
Domain = office
OpenVPN.CACert = /etc/openvpn/cacert.pem
OpenVPN.Cert = /etc/openvpn/user-certificate.pem
OpenVPN.Key = /etc/openvpn/user-key.pem
OpenVPN.Proto = udp
OpenVPN.CompLZO = yes

Then start the connman-vpn service:

systemctl start connman-vpn && systemctl enable connman-vpn

Now, when you start connmanctl services your vpn connection should be listed:

root@edison:~# connmanctl services
* R MyHost        vpn_my_host_com_office
*AO MyWifi        wifi_..._..._managed_psk


ppp is a way to pass an internet connection across a serial line. The line must be full duplex. If you have 2 Edison-Arduino’s you can connect the serial ports together. On Edison-Arduino #1 the Digital header pin 0 (RX) must be tied to pin 1 (TX) of Edison-Arduino #2 and vice versa. I found I need to connect at least 3 GND’s to suppress HF interference (my wires are 10 cm long), for this I used pin 14 (GND) on the Digital header and the 2 GND pins on the Power header.

Setup the serial ports

Currently the UART pins are not correctly setup. This is an open bug in the initrd init script. To setup manually:

gpioset `gpiofind TRI_STATE_ALL`=0 && gpioset `gpiofind TRI_STATE_ALL`=1

Test the connection

To test the connection start a terminal on the console on both Edison-Arduino’s:

screen /dev/ttyS1 2000000

Whatever you type into the one Edison-Arduino console will appear on the other.

Setup ppp

One Edison-Arduino #1 create file /etc/ppp/options.ttyS1:

maxfail 0

One Edison-Arduino #2 create file /etc/ppp/options.ttyS1:

maxfail 0

Prevent DMA from sleeping

We need to prevent the dma controller from entering a sleep state (as waking up can take a long time and cause communication errors, see HSU. The easiest way to do this without coding is to run cyclictest in the background.

Run cyclictest on both Edison-Arduino’s:

cyclictest > /dev/null &

cyclictest sets /dev/cpu_dma_latency to 0. You can not simply echo 0 to this file as it will return to its original value when echo terminate. However, the following will work:

exec 3<> /dev/cpu_dma_latency; echo "0xhhhhhhhh_hexadecimal_latency_in_uS" >&3

root@yuna:~# xxd -l 16 -p /dev/cpu_dma_latency

This must be read as 0x77359400 or 2000 sec. (https://blog.csdn.net/msdnchina/article/details/98659435)

Test the ppp connection

On both Edison-Arduino’s start the ppp server:

pppd /dev/ttyS1 2000000 &

To test the connection, on one Edison-Arduino start iperf3 as a server, on the other as client:

iperf3 -s


iperf3 -c

This will generate output similar to:

root@edison:~# iperf3 -c
Connecting to host, port 5201
[  5] local port 44286 connected to port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec   387 KBytes  3.17 Mbits/sec    0   33.9 KBytes       
[  5]   1.00-2.00   sec   164 KBytes  1.34 Mbits/sec    0   33.9 KBytes       
[  5]   2.00-3.00   sec   195 KBytes  1.60 Mbits/sec    0   33.9 KBytes       
[  5]   3.00-4.00   sec   195 KBytes  1.60 Mbits/sec    0   33.9 KBytes       
[  5]   4.00-5.00   sec   195 KBytes  1.60 Mbits/sec    0   33.9 KBytes       
[  5]   5.00-6.00   sec  97.6 KBytes   799 Kbits/sec    0   33.9 KBytes       
[  5]   6.00-7.00   sec   195 KBytes  1.60 Mbits/sec    0   33.9 KBytes       
[  5]   7.00-8.00   sec   195 KBytes  1.60 Mbits/sec    0   33.9 KBytes       
[  5]   8.00-9.00   sec   195 KBytes  1.60 Mbits/sec    0   33.9 KBytes       
[  5]   9.00-10.00  sec   201 KBytes  1.65 Mbits/sec    0   33.9 KBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  1.97 MBytes  1.66 Mbits/sec    0             sender
[  5]   0.00-10.05  sec  1.81 MBytes  1.51 Mbits/sec                  receiver

iperf Done.

If all goes will there will have been 0 transmission errors:

root@edison:~# ifconfig
        inet  netmask  destination
        ppp  txqueuelen 3  (Point-to-Point Protocol)
        RX packets 618  bytes 32205 (31.4 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1349  bytes 1987637 (1.8 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Setup up routes etc.

You probably want to setup routes etc. Unfortunately doing ppp with connmanctl and having that take care of setting up conenctions, routes etc. using a NULL modem is not supported currently. You need to do that manually.

Further info can be found here How-To: Ethernet Bridge over serial(or xbee).