Keyboard repeating characters


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by jackdw » Mon Jun 25, 2012 1:48 pm
Hi. Got my pi in the post today. Downloaded the debian image from /downloads
It all booted up ok and I got to where I need to login. The problem I have is that my microsoft sidewinder X4 keyboard (unfortunately the only USB keyboard I have) won't type properly on the pi. It's fine on my main desktop computer as I'm typing on it flawlessly now.
It either doesn't register a keypress, or repeats the last key pressed until a different one is pressed. I'm running the board off my 1000mA iphone charger.

I read this thread:
viewtopic.php?f=28&t=4863

But no solution seemed to be found so that's why I'm raising the issue again.

Any help/advice greatly appreciated.

Cheers
Jack
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by abishur » Mon Jun 25, 2012 2:17 pm
A quick look at the keyboard has me thinking that it draws more than the 140 mA the usb ports can send out (which would result in some powering issues).

There are several possibilities that could work and what you do really depends on what you're comfortable with. While I give the suggestion to "buy" something I'm hoping that you have the things on hand to do this without purchasing anything or can borrow something from a friend to test it out before spending money on something that might not work. None of these suggestions are guaranteed to work.

In order of least adventurous to most adventurous:

1) Buy a cheap-o no frills usb keyboard to use with the pi

2) Buy a powered usb hub to plug your existing usb keyboard into

3) Jumper out the usb fuses to bypass the 140 mA limiting current.
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by jackdw » Mon Jun 25, 2012 2:27 pm
Thanks for your fast reply.
The keyboard states it draws 350mA, which I thought would be fine but I assumed the pi supplied the standard 500mA to the USB ports. I didn't realise it was limited to 140mA.

I ordered a small, hopefully low-power, USB keyboard this morning once I received the pi. (I didn't order anything with the pi due to money issues at the time). I've also ordered a 7-port powered USB hub as I'd like to use a mouse and wi-fi adaptor in addition to the keyboard.

In the meantime, I'll have to beg, steal or borrow a suitable USB kayboard.

Thanks again for your help.
- Jack
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by ggreene » Thu Jun 28, 2012 10:28 pm
I wouldn't get carried away with mods just yet.

I too have a Microsoft wireless keyboard (http://www.microsoft.com/hardware/en-us ... yboard-800) where my Raspberry Pi is suffering from repeating characters. The USB dongle reads 50ma - well within the 140ma limit.

Not clear to me yet how to proceed. It crossed my mind the keyboard could use fresh batteries. That's all I've thought of so far.

Good luck.

Interested to hear if anyone knows of a fix or if they've tried other distributions to see if its debian specific.

Does anyone know of wireless keyboards known to work with the debian image? (from debian6-19-04-2012.zip)
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by mahjongg » Thu Jun 28, 2012 11:47 pm
Repeating characters could be a software problem (too) but a keyboard that wants more than 100mA might not be compatible with the PI, and there are more reasons for that than just that the PI is fused at 140mA
The problem is that the fuse will "eat" a large portion of the 5V, so for many USB devices there won't be enough left. The exception are official <100mA devices (AKA "single current unit devices", not to be mixed up with units actually drawing less than 100mA, yes I know its confusing :roll: ).

The simple rule is that the PI is only compatible with units that state implicitly in their documentation that they use less than 100mA, such units are simple wired (and sometimes but not always wireless) keyboards and mice. That is about it! most WiFi dongles use more than 100mA, and also keyboards with built in trackpads, USB mouse connectors, or backlighted keys are normally not in the <100mA category!
If you want keyboard and mouse on one (1) USB port, the best solution is a bluetooth based adapter (using <100ma) with a wireless keyboard/mouse combo that has been tested and is listed as "known good" in the RPI-wiki.
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by ggreene » Fri Jun 29, 2012 1:59 pm
Just a follow-up...

I tried the Archlinux image/distribution last night and same problem (archlinuxarm-13-06-2012.zip from /downloads).

So in my case I've ruled out:
- USB dongle current (limit 100mA, mine is rated at 50mA)
- Distribution (small sample, but Debian and Arch are affected, though it could be they inherit from related or same source for wireless USB keyboard support)
- Port (I tried the both USB ports on the Pi just as a "you never know" test

Seems to me my keyboard could be listed in the "known not working" category.

Ah... now I've just found this... viewtopic.php?f=6&t=5526#p74816

from here... http://elinux.org/R-Pi_Troubleshooting# ... rd_trouble

And its apparently already listed under "Problem USB Keyboards" here... http://elinux.org/RPi_VerifiedPeripherals#USB_Keyboards

Well that settles it for me.

I'll refer to the "known good" list and see if I can find one of those. I see a Logitech MK320 is on sale at a local shop. Might be fortuitous.

Interested to hear how you make out with the new one Jack.
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by Burngate » Fri Jun 29, 2012 4:20 pm
I've been having an interesting time with my keyboards.
1st one, wired, came out of the junk box. Tested fine on the laptop, so plugged into Pi. Log-in "i" password "rasberry" what? Only one key doesn't work - the "p"
2nd one works like a charm, but it's too big, and it absorbs a USB socket.
Down to Maplins, new wireless KB/mouse combo. Rapoo E9070. Works on laptop, onto Pi, works. Reboot, now it doesn't - repeating keys. Must be power problem.
Pi-pass. Keyboard now works. Oh no, it doesn't. Added a cap to the Pi-pass, that cured it. Oh no, it didn't.
Each time I had the problem the old big keyboard would work, and the new keyboard would work on the laptop.
Tried it with a powered hub, same set of problems - so it isn't power after all. Maybe software?
Re-flashed SD card. No different.
Wait a minute - the mouse keeps working all the time! Maybe it's the batteries in the keyboard - new batteries - woopee!
Oh. Stopped working again.

So I think it's a duff keyboard. But I've chucked the packaging, so I can't return it.
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by RaTTuS » Fri Jun 29, 2012 4:22 pm
sudo tail -f /var/log/syslog &
and see what pops up with your keyboard plugged in
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by MasterSplinter » Fri Jun 29, 2012 4:50 pm
I had the same issue in Debian Squeeze distro... Characters would repeat as if a key was stuck.

The KB I used had a hub built into it... I swapped it for a normal KB, and that seemed to fix it. After reading this thread, I suspect the issue was that the hub-keyboard was drawing too much power.
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by devacc12 » Mon Jul 16, 2012 9:15 am
I've tried Debian and Raspbian and get keyboard repeats.
If I use Archlinuxarm I get no problems.
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by dynamik » Mon Jul 16, 2012 10:05 am
I have noticed an interesting 'bug' ??

on cold boot = keyboard works fine.
on warm boot (e.g. sudo shutdown -r now) = keyboard drops/repeats keys
after warm boot, removing an reinserting usb dongle = working fine again.

DELL KM632 Wireless Keyboard ... i cant find power specs on the dongle :?
Debian6-9-14-2012 'squeeze' build

Edit: If I persist with crappy keys and repeat warm boot #2 (without removing dongle) it comes good again. wierd. Seems like a soft bug to me.
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by Montala » Mon Jul 16, 2012 10:45 am
For those using a wireless keyboard/mouse, sometimes the solution can be as simple as just moving the RasPi a bit further away, or even just rotating it slightly... has to be worth a try anyway!
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by recantha » Mon Jul 16, 2012 10:47 am
Yeah, it does seem like the Pi is best if it is not rebooted from Linux, but halted, power out, power in to reboot. Shame as this seems fairly fundamental.

I _have_ got a WiFi dongle + a bluetooth and Rii keyboard/touchpad working on Debian Squeeze v6.
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by Montala » Mon Jul 16, 2012 10:56 am
recantha wrote:I _have_ got a WiFi dongle + a bluetooth and Rii keyboard/touchpad working on Debian Squeeze v6.

Well done! :)

You are using a separate powered hub I assume... which one out of interest?

I do agree with your first comment though.
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by Winerep » Tue Jul 17, 2012 12:49 am
I have tried with a Microsoft Wireless 3000 KB/Mouse combo and the "stuck key" problem existed. I then tried my only USB keyboard/mouse from my iMac, same thing. I chanced upping the voltage to 5.1 at 700a and still same result. Where am I going wrong with this? Before the 5.1v I was trying a 5.0 @ 1.0A.

Is there anything else I can do? I am not going to go further than 5.1 for longer than a minute (less I burn it out). On the wireless I changed batteries to fresh ones and still repeating characters. I haven't even yet been able to log in, each time it tells me wrong login.
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by mahjongg » Tue Jul 17, 2012 2:40 am
5.1 volt won't "burn it out", not even the official 5% over 5.00 volt = 5.25 will do any immediate damage.
It still very possible that even though the average voltage is 5.1 volt, there is so much ripple on the voltage (due to insufficient smoothing)inside the PSU that the voltage dips a 100 times (twice the 50HZ rate of mains power) under the minimum, which might be close to 4.9 volt.
What "can be done about it"? A better, more stable power supply, instead of an unregulated charger, or adding a 10.000 uF smoothing capacitor in between TP1 and TP2 might help (+ of capacitor to TP1).
If you see many kernel messages that happen with a repetition of multiplies of 100Hz, (given you are on a 50Hz supply) they might be caused by an insufficiently smoothed DC voltage.
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by willer » Wed Jul 25, 2012 9:29 am
I am using old Mac G4 keyboard + Logitech Mouse (the keyboard itself is a usb hub with 2 usb output)

http://www.ebay.com/itm/Apple-Macintosh ... 159wt_1187

having same sticky issue :(
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by RaTTuS » Wed Jul 25, 2012 9:45 am
willer wrote:I am using old Mac G4 keyboard + Logitech Mouse (the keyboard itself is a usb hub with 2 usb output)

http://www.ebay.com/itm/Apple-Macintosh ... 159wt_1187

having same sticky issue :(

this will want to draw more power than the RPI can supply , unless you go though a powered USB hub YMMV
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by mechanizeddeath » Sat Jul 28, 2012 5:46 am
I have the same keyboard and the same issues. A shame, because I really like this keyboard. I've tried hooking it up through several different hubs to no avail, the keyboard still repeats characters. I've since given up on it and use a cheap wireless keyboard instead, it works fine and I can stash it out of the way when not in use.

Oddly, the cheaper hardware seems to work better. I have a very nice laser mouse that works intermittently, so I'm using a $5 mouse instead.
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by gsh » Sat Jul 28, 2012 6:20 am
The problem is between the USB driver and the hub, currently our interrupt latency is very poor and the split transactions are not being completed in a timely fashion so the hub is dropping the accesses.

I'm in the process of tracking down and fixing the latency problem at the moment but it may mean slower SD card access!

Anyway will have a look over the weekend, at least I know now what the problem is!

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by fakeplastic » Fri Aug 24, 2012 8:25 pm
Any more info on this? Its so bad that I cant do anything via keyboard, even trying to type "sudo reboot" took over 5 times before I gave up and ssh'd in to reboot. Its incapacitating.

I have a powered hub and power is not an issue. I verified that the key repeats happen whether using the powered hub, using different power supplies, everything I could think of. :cry:

Thank god for CEC on xbmc.

Please, any help/fixes/etc? :|
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by Mad_Sunday » Fri Aug 31, 2012 5:04 pm
This issue was driving me crazy. :shock:
I have a KeySonic ACK-540RF wireless keyboard. The "pull it out, plug it back in" tip above works fine.

Regards, Pete
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by CaptainMark » Mon Oct 01, 2012 10:11 am
I have a Logitech K260 (wireless keyboard/mouse combo) which until recently worked flawlessly with Raspian until the mid September update. Now I have repeating keys issues. I have a 1A HTC charger powering the pi and a 2.5A powered usb hub, both give the same issue and the dongle itself requires only .55mA so it's not a power issue, it worked fine for ages so it's probably a software degression
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by fakeplastic » Thu Oct 04, 2012 9:37 pm
Yah, this seems to be getting worse.

Unplugging and plugging back in doesn't seem to work for me.

Frustration level is extremely high. Is it possible that variation in the hardware can make this worse? Its SOOOOO bad for me.
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by PhilThompson » Tue Oct 16, 2012 3:40 am
Having just received my RPi I thought I'd add my experiences...

Using the no-name 4G SD card supplied by Farnell the problem exists but is manageable. In fact I didn't notice it at first.

Using a SanDisk Ultra 16G card the problem is much worse, to the extent that the keyboard is unusable.

The distro is different (Raspbian on the SanDisk) but other comments suggest that it is not a distro problem.
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