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Dropouts with USB WiFi (802.11b/g/n) Module: For Raspberry P

by perseus286 on Tue Oct 01, 2013 6:42 am

I had a problem with the USB WiFi (802.11b/g/n) Module and my Raspberry Pi. I followed the tutorial and installed the drivers and the adapter connected to the wireless network without trouble. However, after a variable period of inactivity, the adapter would drop out and I would lose my SSH connections from my PC to the Pi. I tried using a powered hub but this didn't help. In the end, I found the answer here in the post by robert84:

http://www.raspberrypi.org/phpBB3/viewt ... start=1125

You're right about those symptoms being power management related. The 8192cu kernel module has power management enabled by default:

Code: Select all
pi@raspberrypi ~ $ cat /sys/module/8192cu/parameters/rtw_power_mgnt
1


I was able to disable power management completely by creating /etc/modprobe.d/8192cu.conf with the following contents:

Code: Select all
# Disable power saving
options 8192cu rtw_power_mgnt=0


After creating the file, you will need to reboot. You can confirm that power management is disabled after rebooting by verifying that the value of the rtw_power_mgnt parameter is now 0.

Code: Select all
pi@raspberrypi ~ $ cat /sys/module/8192cu/parameters/rtw_power_mgnt


After I followed these steps, I haven't had any dropouts. I just thought I'd share this in case anyone else has the same issue.
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by adafruit_support_rick on Tue Oct 01, 2013 9:09 am

Excellent information! Thanks for that. We have had a couple of reports of dropouts - this looks like the cure.
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by adafruit on Tue Oct 01, 2013 10:57 am

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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by perseus286 on Sat Oct 05, 2013 1:23 am

Happy to help :)

I did have one drop-out since I made this change when I left the pi on all day doing a time-lapse. However, that required a reboot of the pi to solve, so it's probably a different problem.
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by getsurreal on Tue Oct 15, 2013 1:11 pm

I'm having the same problem with dropouts. I found the same article and applied the changes, but I'm still having dropout issues.

I've confirmed that 0 is showing when I run

Code: Select all
cat /sys/module/8192cu/parameters/rtw_power_mgnt


If I unplug/plugin the adapter it reconnects. I'm using a powered USb hub to plug the dongle into.

Are there any other ideas on resolving this?
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by adafruit_support_mike on Tue Oct 15, 2013 2:29 pm

If it isn't the power-management issue, we're back to looking for interference in the connection.

What do you get as output from `netstat -d -i`?
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by alexcorvis on Tue Nov 05, 2013 7:59 pm

getsurreal wrote:I'm having the same problem with dropouts. I found the same article and applied the changes, but I'm still having dropout issues.

I've confirmed that 0 is showing when I run

Code: Select all
cat /sys/module/8192cu/parameters/rtw_power_mgnt


If I unplug/plugin the adapter it reconnects. I'm using a powered USb hub to plug the dongle into.

Are there any other ideas on resolving this?


I had the same error explained here and finally today i found the solution and i got working my Wifi Nano Adapter (chipset RTL8188Cus).

Edit the same config file (8192cu.conf) with:

options 8192cu rtw_power_mgnt=0 rtw_enusbss=1 rtw_ips_mode=1

Reboot and check the values of this 2 parameters are the given ones:

cat /sys/module/8192cu/parameters/rtw_enusbss
cat /sys/module/8192cu/parameters/rtw_ips_mode

With this configuration my wifi nano adapter works like a charm! (bye bye freezings and hangings!)

If you want +info, plz try: (Note: It´s in spanish, but it explains the possible values for the parametres) http://www.miraspberrypi.es/2013/05/sol ... tl8188cus/

Plz give us feedback when you´ll try it!
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by adafruit_support_mike on Wed Nov 06, 2013 2:16 am

Very interesting.. thank you for the information!
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by CactusMonkey on Fri Dec 06, 2013 10:37 pm

I have been having similar issues but think that I am close to keying in on the issue... (well my issue at least).

Like most everyone else, I can't survive with only two usb connections so I purchase the Manhattan USB hub. Unfortunately, in any configuration where the hub is involved, the USB wifi manages to draw way too much current (when I pull it from the USB slow, it is incredibly hot). Restarting momentarily works- until the wifi unit gets hot again....

My fix for the time being is to ssh to do the basic stuff with my RPi (the VNC set-up in Adafruit lesson 7 doesn't work for my Linux machine.... I blame VNCViewer but will take some help/advice on this... is there a thread?). Anyway, after pulling the USB hub from the equation, internet has been running quite strong.

Check out these two threads for more info on the wifi/usb hub problem:
http://www.raspberrypi.org/phpBB3/viewt ... v8#p156138
http://www.raspberrypi.org/phpBB3/viewt ... 28&t=48812
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by adafruit_support_rick on Sat Dec 07, 2013 2:21 pm

Which WiFi dongle do you have ? It shouldn't be getting hot in a USB hub. The issue in those threads you posted is that the network/usb chip on the Pi itself runs at up to 70ºC, and the heat gets transferred to the USB jack and the dongles.
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by CactusMonkey on Sat Dec 07, 2013 5:39 pm

Weird.... I am using the miniture WiFi (802.11b/g/n) Module (adafruit part id: 814). Any reason it would get hot in the Raspberry Pi and stop working? What about in the Manhattan USB hub (http://www.amazon.com/gp/product/B0035L ... UTF8&psc=1)?

Thanks for any info or help in advance!
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by adafruit_support_rick on Sat Dec 07, 2013 5:58 pm

Sounds like it's defective. Please email support@adafruit.com with a link to this thread for a replacement.
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by CactusMonkey on Sun Dec 08, 2013 9:04 am

Hi Rick,

The USB Wifi itself does not seem to be defective. If I have only the USB wifi and either a keyboard or mouse plugged in everything works fine (as this isn't practical, I've been using mostly ssh connections).

The USB Wifi only seems to drop (and get incredibly hot) when I use the Manhattan USB Hub. I've tried an assortment of configurations, but no luck....

While the hub is powered, it doesn't appear to power the RPi (that is, the Pi won't power up if the hub is plugged into and the RPi's power supply is disconnected).

Thoughts?
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by adafruit_support_rick on Sun Dec 08, 2013 9:09 am

The hub won't back-power the Pi through the PI's USB jack. The Pi isn't designed that to allow that.
Do you have a different hub you can try? It's possible that it's the hub that is defective.

The difference between plugging the WiFi into the Pi and into the Hub is that the hub can provide more a lot more power to the WiFi dongle than the Pi can. So it doesn't really prove that the hub is at fault if the dongle gets hotter.
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Re: Dropouts with USB WiFi (802.11b/g/n) Module: For Raspber

by Juggler00 on Mon Dec 09, 2013 10:28 am

I too have purchased both the USB WiFi (802.11b/g/n) Module with Antenna for Raspberry Pi and am powering it using the 5V 1A (1000mA) USB port power supply - UL Listed. My particular use case was for a Raspbmc set-up, but I've had nothing but headaches trying to get the WiFi to work.

I found this thread I was hoping someone could help me out on how to disable power managment on Raspbmc?

cheers,
S.
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