512MB Raspberry Pi with EDIMAX EW-7811un and MK320 Combo


25 posts
by rgvraspi » Sat Nov 03, 2012 4:13 pm
I have the latest 512MB Raspberry Pi with a Logitech MK320 keyboard/mouse combo powered by a Rocketfish USB Charger that is rated at 2.1A. The device is connected directly to my router via the ethernet connector and works well as does my original rev 1 256MB Raspberry Pi. I am using Raspbian Wheezy which I keep updated.

Since I wanted to use one of them in another room I realized that I would need a Wifi adaptor. I always look at the Raspberry Pi compatibility list as well as the forums to choose the most compatible devices and I settled on the EDIMAX EW-7811Un since it seemed it could run without a powered hub.

I am using the Wifi Adaptor with the 512MB model. It seems to work fine, but of course (And there's always a but right?) I am now running into the intermittent stuck and/or repeating keyboard phenomenon again. I say again, as the first time I came across this was when I received my original 256MB model. Switching the USB power supply cured that in agreement with what seems to be a common symptom on the forums.

I am still not completely clear on how much power the USB ports on these devices can supply. I read the 256MB model can only supply 140ma maximum for instance, but is that for both USB ports combined, or for each port? Since the 512MB device has the polyfuses removed, does that mean the power for the USB ports is only limited by whatever power is available or are they still limited to a certain level?

I guess my final question is, do any others have this same combo of MK320 keyboard and EDIMAX adaptor working ok? I am trying to ascertain whether this is just a software conflict of some sort or it's a power issue again. ie is the combination of the MK320 wireless and EDIMAX Wifi adaptor likely to be too much for the USB ports to cope with even on the 512MB model?

Apart from the annoying intermittent keyboard issue, it seems to be quite stable accessing the internet and a speed test shows no issues there either.
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by sjfaustino » Sat Nov 03, 2012 6:37 pm
I'm powering a 2,5" USBHDD from one of a 256MB rev.2 Pi's USB ports (had to power the Pi thru the GPIO since the micro-USB polyfuse would not let enough power go to the USB), so no worries with the amount of power that the USB's can supply.

With the Pi powered thru the micro-USB, I can use a keyboard and wi-fi pendrive on a rev.1 Pi.

Just as a matter of debugging, what is the power measured at the Pi, if you disconnect the wifi and connect directly thru Ethernet, do you have the keyboard issue and finally, have you tried using a USB extender cable so that you don't have 2 radio devices on top of one another?
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by rgvraspi » Sat Nov 03, 2012 8:17 pm
Thanks for the reply.

Just as a matter of debugging, what is the power measured at the Pi, if you disconnect the wifi and connect directly thru Ethernet, do you have the keyboard issue and finally, have you tried using a USB extender cable so that you don't have 2 radio devices on top of one another?

I haven't done any power measurements but both models seem to work fine using the MK320 wireless keyboard/mouse combo connected to the network via Ethernet. It's only when I use the WiFi adapter on either model that I get the sticky and/or repeating key issue.

I found a USB extension cable and placed the EDIMAX on the end of that away from the Pi. The problem is still there and since it's intermittent, it's hard to know if it's improved or just the same as before since you have to do quite a bit of typing before the stuck key problem happens. This also makes testing rather tiresome! :)

This is one of those problems where it doesn't occur often enough to make using the Raspberry Pi useless, but it's still often enough to be annoying. I guess next step may be borrow the powered USB HUB from my PC to see if that improves things but as I didn't plan on attaching anything else to the Raspberry Pi it seems like an overkill just for this tiny adapter.
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by sjfaustino » Sun Nov 04, 2012 1:11 pm
rgvraspi wrote:I guess next step may be borrow the powered USB HUB from my PC to see if that improves things but as I didn't plan on attaching anything else to the Raspberry Pi it seems like an overkill just for this tiny adapter.

That will tell you if the problem is hardware (not enough power) or software.
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by rgvraspi » Wed Nov 21, 2012 6:21 am
Well I purchased a Belkin F5U234 USB Hub. It seemed like it was helping initially, but the stuck/repeating/missing a character problem still came back. I have tried many different combinations, even plugging one of wireless adapters on the Raspberry Pi itself to keep them apart for interference purposes.

Considering I am using a 512MB model which is supposed to be more power friendly to USB devices and have used a powered hub, I can only assume it isn't likely a power issue. I have tried it powered by the hub and powered by a separate psu. Just as I think I found a combo that works, it rears it's ugly head again. This problem seems to vary with the wind which makes it more frustrating in that sometimes it's now and then, or not at all, and other times it seems more frequent.

Of course it doesn't help that I have done updates as well to try and see if that would fix it. So I can never be sure it an update made it worse, or it was always like that. Very frustrating.

The wireless keyboard seemed to work fine with Ethernet and it works fine if I use a wired keyboard with the WiFi adapter, without the hub. I have tried to isolate what may be causing this, but I guess they just don't seem to like each other for some reason.

Oh well I guess I'll just have to limp along for the time being, hoping it's a software problem that will eventually get fixed in an update or two from now.
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by bazpaul » Fri Nov 23, 2012 4:39 pm
Hey guys, i have the edimax 7811un and was thinking of buying a MK320, but this thread is turning me off.

Are you saying that the two will not work together?

and that its a wireless issue not a power issue?

I find the pi quite frustrating, there are so many compatibility issues, its annoying!
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by rgvraspi » Fri Nov 23, 2012 7:53 pm
The EDIMAX WiFi adapter seems to work fine, even with the keyboard attached. The problem I am having is the repeating key issue and I can only assume it had something to do with the WiFi adapter as I don't remember this problem before I purchased it. The frustrating thing is, that it's not consistent. Sometimes when I use the Raspberry Pi it doesn't seem to have the issue (at least initially anyway) while other times I will. I have tried isolating the problem but it gets really exhausting after a while.

I am generally enjoying using my Raspberry Pi, and don't have any complaints about performance etc. so I don't want this to come across as unwarranted moaning. I am just trying to grope at straws to see if there is a solution I may have missed.

What makes it more frustrating, is that I even briefly had the key problem appear when I had the EDIMAX disconnected. It seems it only happened once, but I had never had that before when I was only using the Ethernet.

Now to be fair, it's not so bad as to make my use of the Raspberry Pi unusable, but obviously doing stuff where there is a lot of typing, it's going to pop up, although sometimes it will pop up and interfere when I am typing a command line. It wouldn't be so bad if the issue was consistent, then it would be much easier to rule out what does and doesn't work rather than what might or might not.

I think I read someone who had a keyboard issue seemed to have gotten rid of it simply by backing up and recopying the image back to the card, though I can't remember if it was the same card or another one that was a duplicate. Even then, only when a significant period of time has passed without issue would I consider it cured.

I have been hearing of SD Card corruption issues, and since this type of problem is not consistent, I wonder if it's all related? I may even try a different distro to see if that solves it. The problem is that this all takes a lot of time and often just as you think "Finally it's Solved!", the issue comes back.

I guess the Raspberry Pi is at least fulfilling one of it's purposes, that of learning how to troubleshoot a small Linux computer :) It also seems that including Scratch to teach kids programming may well be a fortuitous choice since it doesn't need a lot of keyboard input!
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by bazpaul » Fri Nov 23, 2012 8:25 pm
yeh but i am confused - do you have a wireless keyboard or wired????

I think the OP had a problem with a wireless USB paired with a EDIMAX

i want to buy a MK320 tomorrow, but not if it wont work in conjunction with a edimax wireless usb.

Also OP - when you use a wired keyboard and the EDIMAX do you have any issue?
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by rgvraspi » Fri Nov 23, 2012 9:59 pm
I *am* the OP and stated that I am using the Logitech MK320 with the EDIMAX EW-7811Un. I guess my verbosity fooled you into thinking I was a new poster :)
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by bazpaul » Fri Nov 23, 2012 10:03 pm
rgvraspi wrote:I *am* the OP and stated that I am using the Logitech MK320 with the EDIMAX EW-7811Un. I guess my verbosity fooled you into thinking I was a new poster :)


ha ha ha i'm just tired......long week at work :)
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by bazpaul » Fri Nov 23, 2012 10:05 pm
I'm trying to set up my Pi as a media center with Xbian - but to be honest it's more hassle and stress that it's worth...

I'm thinking of getting a mini Pcand installing XBMC there

http://www.ebay.co.uk/itm/Mini-Gaming-PC-512MB-40GB-CD-Pentium-4-P4-HT-Gigabit-LAN-Windows-7-8-Compatible-/360514459096?pt=UK_Computing_DesktopPCs&hash=item53f05615d8
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by sjfaustino » Fri Nov 23, 2012 11:14 pm
First of all, have you requested any help with your issues with XBian?
I'm using 3 Pi's with no problems.

Second, good luck using a P4 800MHz with an Intel graphics card as an HTPC :shock:
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by bazpaul » Fri Nov 23, 2012 11:29 pm
sjfaustino wrote:First of all, have you requested any help with your issues with XBian?
I'm using 3 Pi's with no problems.

Second, good luck using a P4 800MHz with an Intel graphics card as an HTPC :shock:


Yeh I have looked for help - i think it might be power supply issues! But I need a wireless USB and wireless keyboard but this thread doesn't inspire me :)

regarding the HTPC - I know!!!! I would need to stick a simple graphics card (below) in there. no way could i use on-board graphics!

http://www.ebay.co.uk/itm/Nvidia-Quadro-NVS-280-PCI-Dual-display-card-DVI-fh-/260741378529?pt=UK_Computing_Computer_Components_Graphics_Video_TV_Cards_TW&hash=item3cb565b1e1
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by rgvraspi » Sun Dec 02, 2012 7:38 pm
I was updating this thread to let you know what I have done so far. I decided to re-image the SD Card and download and burn the latest 10-28-2012 Raspbian Wheezy to see if that fixes the issue. Well it seemed that so far was so good in that I seemed to be able to type text without incidence. I then decided to finally make this post and what do you know, I jinxed it! All of a sudden I got a stream of the last character I typed across this post.

Having said that I am using Midori (because I didn't want to update anything yet to help keep possible causes to a minimum) and I noticed as I am typing the CPU meter is running full blast so it may have been caused by that since all this text has been typed so far without a glitch. Well apart from that incident of course!

I am hoping that it was due to some sort of corruption. I can cope with the keyboard issue if it happens once in a while but not as often as sometimes it has been happening. Well so far so good. I had better not push it so will end the post here! Fingers crossed that I won't be making an immediate follow up post about how it came back with a vengeance :(
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by rgvraspi » Sun Dec 02, 2012 11:22 pm
Well that didn't last long. I turned it on a little while ago and sure enough the problem is back:

As you can see here:

ere is an example of a entence at I yped where you can now se missing characters

How abot this as a good example of charrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr

I am now going to try a different SD card just in case the one I am using is somehow getting corrupted though I have my doubts it's that.

If the new card doesn't fix it I'll have to just plug in a wired keyboard to see if that fixes the problem although it's not really practical to use one long term where I am using my Raspberry Pi. I just hope I don't have a faulty device.
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by rgvraspi » Mon Dec 03, 2012 2:21 am
I have since gone back to the original SD Card and attached a wired keyboard and mouse I had lying around. Thankfully they have fairly long cables otherwise they wouldn't be usable in it's current location. It's one reason I am trying to use a wireless combo.

So far so good, had no issues so far. I will see how this works out. At least to rule out a more serious problem although have seen in another thread someone else who said they couldn't get two wireless devices working together either.

I noticed the stuck key symptom did seem to occur once or twice when testing the Logitech Mk320 on its own but nowhere near the extent it does when attached with the WiFi adapter so I am trying to work out if the MK320 isn't quite as compatible as I had been led to believe in the compatibility list. I wonder if any others have had issues with this keyboard? Perhaps the conflict with the WiFi adapter just 'amplifies' a minor but existing problem? I hadn't notice the problem before. Perhaps I had never done enough typing or it's because I was using a different combination of updates etc.
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by gsh » Mon Dec 03, 2012 6:49 am
We do still see the keyboard issues when the Pi is very heavily loaded, so using an X interface and a WiFi connection is touch and go.

I would be very interested to see if you think it's always broken or only sometimes broken... I've got a hypothesis for the current issue which would mean it would be possible to implement a improvement (rather than a fix).

My own Pi running RaspBMC with a £1.80 remote from ebay and wired ethernet sometimes drops keys, but once it starts (after a boot) no matter how long I leave it it'll still be bad. If I then reboot it'll work fine... Does anyone else have this...

Gordon
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by rgvraspi » Tue Dec 04, 2012 5:54 am
When the problem occurs on mine, it happens even at the command line when x is not running so not related to the GUI.

I don't know what's going on. Sometimes I will use the Raspberry Pi with the MK320 keyboard/mouse combo and EDIMAX Wifi Adapter, and it will work fine ie no missed characters etc. At least for while anyway. Yet many other times it won't.

It's not a power issue as I have tried it both directly powered from the USB HUB and with a separate dedicated USB power supply to the Raspberry Pi.

If I start having the issue and I swap the the wireless keyboard/mouse for wired ones, the problem goes away and I am back to fluid character output with no stuttering or repeating so far.

What I may do is perhaps try out another Linux distro just to see if that makes any difference.

I guess the Raspberry Pi is living up to it's purpose with me at least lol
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by rgvraspi » Wed Dec 19, 2012 5:21 am
I thought I would post an update here. In desperation I tried the dwc_otg.speed=1 setting in my /boot/cmdline.txt file to reduce my USB speed back down to the older 1.1 standard.

So far for the last two days it appears to have fixed the problem!

I also tried removing the setting and within a very short time, the problem of the stuck/missing characters came back. Since I have put it back however I haven't had the problem reoccur. Of course, I will only believe it fixed when I've gone at least a week or so without it happening, even though normally by now it would've already come back.

All my devices are, including the hub, all USB 2.0 but I don't have anything that currently requires USB 2.0 speeds. Of course in the future this setting may have an effect if I get a device that I do need the USB 2.0 speed but I did an internet speed test and it seems the Wifi Adapter is still fast enough for my purposes.
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by efflandt » Wed Dec 19, 2012 6:48 am
I see that you found the fix I was going to suggest. I have to use dwc_otg.speed=1 for my older Logitech di Novo Edge wireless keyboard/mousepad to eliminate dropped/stuck keys. But the dropped/stuck keys originally happened when using ethernet before I had mini-WiFi (different brand) directly on the Pi.
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by rgvraspi » Wed Dec 19, 2012 2:18 pm
Yep. I had known of this fix for a while, but I can't remember why I didn't try it before. I think I had thought I read that it was only for situations where you had a mix of 1.1 and 2.0 USB devices and that it would also impact the SD card speed etc.

Also when I was searching the forums I don't think at the time I had seen it applied to a wireless keyboard. That plus the fact that it worked fined when I had my device on Ethernet a while back, I guess convinced me it was the WiFi adapter that was causing the problem even though it seemed to now do it a bit without the adapter now. The problem is it gets tedious testing for each combination of hardware and software for a problem that doesn't happen consistently as you get fooled into thinking you fixed it and then it comes back.

Anyway I am very happy now as my device is much more usable! I hope they eventually fix the USB 2.0 drive issue though.

efflandt wrote:I see that you found the fix I was going to suggest. I have to use dwc_otg.speed=1 for my older Logitech di Novo Edge wireless keyboard/mousepad to eliminate dropped/stuck keys. But the dropped/stuck keys originally happened when using ethernet before I had mini-WiFi (different brand) directly on the Pi.
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by vroberts » Fri Jan 11, 2013 5:38 pm
Some of the problem may be related to the fact that the Logitech RF dongle operates near the same frequency as the USB WiFi adapter. The transmitter in the WiFi adapter may be overloading and interfering with the receiver in the Logitech adapter. The problem may be that the two RF adapters are right next to each other.
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by theWeakForce » Sat Jan 26, 2013 3:08 am
vroberts wrote:Some of the problem may be related to the fact that the Logitech RF dongle operates near the same frequency as the USB WiFi adapter. The transmitter in the WiFi adapter may be overloading and interfering with the receiver in the Logitech adapter. The problem may be that the two RF adapters are right next to each other.


Interference came to my mind as well...
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by ajaxmob » Mon Jan 28, 2013 4:41 am
Great info in this thread, thanks rgvraspi. I'm currently in the process of ordering a Logitech K400 and Edimax wifi, and I was wondering if I would have to use a powered USB hub... Seems like this sticky key problem is across the board on most wireless keyboards, good to know that the dwc_otg.speed=1 fix is a possible (or probable) solution.
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by rgvraspi » Wed May 01, 2013 3:07 am
Out of interest I recently received a Model A. I wondered if having the direct single USB without the on board HUB would make any difference and it seems it doesn't. I haven't tried the dwc_otg.speed=1 fix yet although I see no reason for it not to work. I constantly keep my Pis updated so I can only assume the problem of the Hi Speed USB has yet to be solved. Still the dwc_otg.speed=1 fix has transformed my Model B into a quite usable little device now. If the USB problem could be solved, it would be perfect :)
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