WiFi Pain - Edimax EW-7811un only works on powered hub

[plettschner]

I had been running the pi over an ethernet connection and all was well. Recently, I decided I would get the ever-popular Edimax EW-7811un USB WiFi adapter so I could use the pi in another room... has not gone smoothly. Throwing my arms up over here and asking the forum.

Here's where I am at...
Plugged the EW-7811un into the pi, booted up, device recognized, sweet! Nope, no connectivity. lsusb shows it there, ifconfig shows it ok, iwconfig looks good... can't ping anything and can't SSH into the pi.

I had also bought that butt-ugly Pluggable 7 port USB hub, so I decided to try that with the Edimax WiFi... sure enough, it works fine.

I tried all different settings to get it to work plugged directly into the pi... DHCP, staic IP, putting the SSID and psk in /etc/network/interfaces, using the GUI config, manually editing the files... occasionally, it would work a little, but erratically, most times it wouldn't. I tried three different power supplies, two different USB cables, disabling eth0, restarting wlan0. Ran apt-get updae, apt-get-upgrade, and rpi-update... no change.

I'm back to using it on the powered hub... I'm admitting defeat for now.

Anyone else run into this? Suggestions? I've read through pages of forum posts and articles on the 'net for the last two days... just not getting anywhere it seems.

Here's my current etc/network/interfaces, WiFi is working with Edimax dongle plugged into hub (no, that's not really my SSID and psk):

Code: Select all

pi@raspberrypi /etc/network $ vi interfaces
auto lo
iface lo inet loopback

iface eth0 inet static
address 192.168.0.232
netmask 255.255.255.0
gateway 192.168.0.100

auto wlan0
allow-hotplug wlan0
iface wlan0 inet static
address 192.168.0.234
netmask 255.255.255.0
gateway 192.168.0.1
wpa-ssid "Fozzy D Bear"
wpa-psk "wakkawakkawakka"

~
~
~
~
~
~
"interfaces" [readonly] 17 lines, 295 characters

And results from lsusb:

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pi@raspberrypi ~ $ lsusb
Bus 001 Device 002: ID 0424:9512 Standard Microsystems Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp.
Bus 001 Device 004: ID 1a40:0201 Terminus Technology Inc. FE 2.1 7-port Hub
Bus 001 Device 005: ID 413c:2107 Dell Computer Corp.
Bus 001 Device 006: ID 7392:7811 Edimax Technology Co., Ltd EW-7811Un 802.11n Wireless Adapter [Realtek RTL8188CUS]

iwconfig:

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pi@raspberrypi /etc/network $ iwconfig
wlan0     IEEE 802.11bg  ESSID:"Fozzy D Bear"  Nickname:"<WIFI@REALTEK>"
          Mode:Managed  Frequency:2.422 GHz  Access Point: 00:1A:C4:CD:45:51
          Bit Rate:54 Mb/s   Sensitivity:0/0
          Retry:off   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=90/100  Signal level=74/100  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

lo        no wireless extensions.

eth0      no wireless extensions.

Anything else I should post?

EDIT: I failed miserably on following directions here! Forgot to post what hardware and OS!
Raspi B version, running Raspbian Wheezy, off of an 8GB SD card, loaded from NOOBS. Card was loaded last month.
Linux raspberrypi 3.10.32+ #648 PREEMPT Fri Feb 28 16:29:56 GMT 2014 armv6l

[plettschner]

Is there a way to tell if I have a defective WiFi adapter? Pulling too much current for the onboard USB port maybe?

[RCobbTX]

My sympathy's. I have purchase three WiFi's plug in's. I failed at installing all three, I'm guessing they work on somthing. They sell these for the Pi but my experience is that the documentation is poor and and they do not work on the RaspberryPi.

[klricks]

What else is connected to the RPi? If anything other than a basic wired USB keyboard and mouse then the WIFI is not likely to work.
Is your RPi Rev 1 or 2? WIFI won't work on a Rev 1 (256MB) board without mods to the RPi.

[plettschner]

Only thing connected is a Dell USB keyboard and HDMI out to a monitor.

it's a B Model, Rev 2, 512MB

Edit: For clarity...

Code: Select all

pi@raspberrypi /var/log $ cat /proc/cpuinfo
processor       : 0
model name      : ARMv6-compatible processor rev 7 (v6l)
BogoMIPS        : 2.00
Features        : swp half thumb fastmult vfp edsp java tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xb76
CPU revision    : 7

Hardware        : BCM2708
Revision        : 000e
Serial          : 00000000971
pi@raspberrypi /var/log $

[plettschner]

Apparently, I'm a glutton for punishment... I just ordered another EW-7811un. Hoping to see if there is any difference.

[plettschner]

No difference with a new Edimax dongle.... interesting.

The only other thing I can think of, other than the actual Pi having an issue, is having XRDP is installed on it. Not really much is changed from the original install that would be related to networking... though, it still works fine using a USB hub.

Anything else I should be looking at or checking?

[MrEngman]

What else is connected to the RPi? If anything other than a basic wired USB keyboard and mouse then the WIFI is not likely to work.
Is your RPi Rev 1 or 2? WIFI won't work on a Rev 1 (256MB) board without mods to the RPi.

I have my RPi Rev 1 without any mods running with an EW-7811Un connected directly to the USB port connected with a USB A-B extension cable and I have not had any trouble with it. The keyboard and mouse are connected using an old Belkin powered hub. Try a decent power unit.


MrEngman

[GTR2Fan]

I have my RPi Rev 1 without any mods running with an EW-7811Un connected directly to the USB port...and I have not had any trouble with it.

Same here.

[plettschner]

Narrowing it down a little more... got my second Raspi yesterday, setup SD card with same NOOBS image, booted up into Raspian with the EW-7811 in one of the USB ports... bam! It works.

So, new Raspi, fresh Raspian install, Edimax WiFi works off of onboard USB port.

Both Raspis are powered off of the same Pluggable 7-Port USB hub, both have same version of NOOBS/Raspian, both with same WiFi dongle.

Next up: Try to determine if it's hardware or software causing the issue on the other Pi by swapping SD cards... will report back later.

[goldberg]

Many other RPi users (including myself) have been experiencing similar difficulties in getting WiFi dongles to work reliably on RPi. I added a post recently to the forum: "Frustrating internet unreliability from my Raspberry Pi".

I have been testing several different Raspberry Pi(e)s and three different dongles including the Edimax, but still haven't found a solution, even though I'm using the PiHub powered hub. Today I had a look at the internet postings relating to the SMSC LAN9512 chipset which provides the USB and LAN connectivity on the RPI, and also the Linux drivers for this chipset. However, the content of many of these postings are well beyond my technical competence.

[plettschner]

And oddly enough, I now have the both working with the WiFi dongles plugged into the pi(s).

Yeah... how about that? No idea.

I took SD card and dongle out of Pi1, stuck them into Pi2, powered it up and it worked. Put dongle and SD card from Pi2 into Pi1, powered it up and it worked... swapped SD cards back around and they both still work.

One is DHCP, other is static IP

The fart if I know why they work now.

[mahjongg]

perhaps you have had overloaded (bad) polyfuses, meaning that not all of the 5V reached the WiFi adapter, or the 5V became noisy (unstable) due to current variations causing variations in the 5V reaching the adapter. Such adapters, with their sensitive radio circuitry are very susceptible to voltage variations and drops. Leaving the polyfuses unpowered will eventually "heal" them. Thats my theory at least.
Instead of powering the adapter (USB port) by the PI, another solution than using a HUB, is to use a "power split Y-cable", or simply cut the 5V line to the USB port, and power it directly, just like you could do to power a current hungry external HD.
Use a clean PSU, not a switching power supply which injects a lot of HF noise into the 5V supply.

[plettschner]

I don't know... pretty much all power supplies for electronics/computers are SMPS... some definitely "quieter" than others.

When the dongle is in the hub, it works fine... Pi is powered off of the same hub (Pluggable 7-port). If the dongle is in the Pi or in the hub, power is still coming from the same source. So, off of the same power source and hub, I've had both Pi working, one Pi working and neither Pi working, in regards to direct-plugged WiFi dongle.

Today, after a few reboots, neither is working.

Oh, wait, after another reboot, Pi1 is working. Time to reboot Pi2 again and see what happens.

[mahjongg]

Creating some physical distance between the PI and the WiFi dongle might also help minimizing interference between the PI and Dongle, just a short (15cm) cable could already make a difference.

[GTR2Fan]

Creating some physical distance between the PI and the WiFi dongle might also help minimizing interference between the PI and Dongle, just a short (15cm) cable could already make a difference.

I'd agree with that, but make sure it's a properly shielded USB cable or it could make matters worse.

I tried a similar thing with my main PC early last year and had all sorts of problems to start with, until I discovered that the short USB cable I was using had absolutely no shield braiding whatsoever making the whole length behave like an aerial. I've always gone for USB cables with a clear outer sheath ever since so I can actually see the braiding.

[mahjongg]

yeah, obviously I meant shielded cable, thanks for the completion. a ferrite clamp around the cable might further improve the matter.

[plettschner]

Update on the situation...

Apparently, I have an affinity for outdated technology. I was still running the 2Wire 2701HG WiFi Gateway on my DSL connection... it only supports 802.11b/g. I do have a Linksys E2000 WiFi router loaded with DD-WRT firmware that I've been meaning to hook up for months now. Well, I noticed that when I was having these WiFi issues, my wife's PC was also having issues connecting over the WiFi until I rebooted the gateway (not an IP conflict either). Hmmmm, I started looking at my network as being part of the problem.

Last night, I bridged the 2Wire gateway and turned off the WiFi so it only acts as a DSL modem now... dropped in the E2000 to handle the routing, PPPoE connection, and WiFi. Now with a better wireless network, and 802.11b/g/n, both Pi's have been connected solidly with the Edimax dongles plugged into onboard ports.

This still doesn't really explain why they worked when plugged into the powered hub... unless, maybe, 802.11g mode requires significantly more power to function than 802.11n?

Anyway, I do not recommend using the Edimax EW-7811 over 802.11g, with a 2Wire 2701HG DSL Gateway! Now to get around to ordering the Cable internet connection