WIFI randomly disconnects only when powered by AC

So when I run a socket connection from my tablet to my BBB (Latest Angstrom) running a python socket server. The BBB randomly loses WIFI connection when I am connected solely AC, but when I am also connected through USB it doesn’t. The Wireless card is plugged into a powered USB hub as well (it is a edimax micro wireless usb).

I am driving to WheelChair Motors with two Simple-H motor controllers. It takes 4 PWM signals and 2 GPIO signals. I am using Adafruit’s BBIO library to control them.

Weirdly ifconfig indicates that wifi is still connected, when I check the router it says it is not connected…

Any Ideas?

Relevant Network Information below:

root@beaglebone:~/Dalek Server# iwlist wlan0 scan && ifconfig wlan0 && iwconfig wlan0
wlan0 Scan completed :
Cell 01 - Address: 00:18:E7:DD:52:2E
Protocol:IEEE 802.11bgn
Frequency:2.412 GHz (Channel 1)
Encryption key:on
Bit Rates:144 Mb/s
IE: IEEE 802.11i/WPA2 Version 1
Group Cipher : TKIP
Pairwise Ciphers (2) : CCMP TKIP
Authentication Suites (1) : PSK
Quality=100/100 Signal level=69/100

wlan0 Link encap:Ethernet HWaddr 80:1F:02:0B:97:CF
inet addr: Bcast: Mask:
inet6 addr: fe80::821f:2ff:fe0b:97cf/64 Scope:Link
RX packets:5213 errors:0 dropped:5268 overruns:0 frame:0
TX packets:5702 errors:0 dropped:175 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:584705 (571.0 KiB) TX bytes:2988953 (2.8 MiB)

wlan0 IEEE 802.11bgn ESSID:“BoomersWIFI” Nickname:“WIFI@REALTEK
Mode:Managed Frequency:2.412 GHz Access Point: 00:18:E7:DD:52:2E
Bit Rate:150 Mb/s Sensitivity:0/0
Retry:off RTS thr:off Fragment thr:off
Encryption key:------- Security mode:open
Power Management:off
Link Quality=2/100 Signal level=2/100 Noise level=0/100
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

Check your grounds. Make sure all power supplies are grounded and plugged into the same power strip. Make sure your power supply has a three prong AC plug, giving a good earth ground reference. Same for the HUB.

Sounds to me like the ground is coming over the USB connection.


could also possibly be a loose or faulty barrel jack connector ( in some way ) ? Or even a power connector cable that is some how internally damaged ?

I have seen that as well. People grabbing an barrel jack that is like a 2.5mm instead of a 2.1mm.


Hmm both power supplies are two prong, but the BBB doesn’t loose power. If I plug in the USB, I am able to ssh into via, and run ifconfig, iwconfi, and iwlist. The first two reveal that it thinks it is still connected with very low signal, while the scan reveals that it it getting much better signal than it thinks. Also I checked the application that was running to see if it had ended due to a disconnected, because it was started over wifi ssh, and it was still running…

Does this mean it is not a power issue?

I am going to double check my connections and try again tonight, maybe it is grounding.

what gerald is saying is that grounding is of top importance

bad grounds in any RF system can cause very weird behavior

I never said it would lose power. If grounds are not properly connected, it can introduce noise. Noise can cause all sorts of issues. This may or may not be your issue.

You said connecting USB made it work. When USB and DC are connected, it runs off of DC. All the USB provides in this case is, the ground.