Power issues - Gotta be kidding me

[bursty]

Hi,

So I bought a raspberry Pi off Element 14 and bought a powered usb hub and had it connected with a wireless adapter, wired keyboard and mouse. Oh and a HDMI > DVI cable.

Originally I would be getting keyboard issues like spamming keys, deleting letters etc. which is related to power issues. Unplugging the hub fixed the issue but then i was able to only plug in my keyboard and mouse.

Today I went out and bought a wireless keyboard/mouse combo with one usb receiver and had my wireless usb plugged in. Once again i'm getting keyboard issues related to power. It's quite frustrating that you can buy a device which cant even power its own 2 USB inputs.

Does anyone have any idea what I should do because i'm pretty damn frustrated that i've bought all of this stuff that doesn't work even after reading the wiki on another website with users confirming it works..

P.S my hub is self powered so i'm not sure how the Pi cant even power that thing.

[jamesh]

A few things you can do.

Ensure you are running the very latest distro and have run the updates to get the latest stuff (rpi_update etc) - there have been USB fixes in their that may help.

Make sure your power supply is up to the job, 1A should be enough, and its needs to be a decent supply that doesn't fade voltage as current increases.

Make sure the uUSB cable you are using is decent quality - we have had quite a few reports like this that turned out to be dreadful quality USB power cables.

[Tyrandis]

Buy yourself an apple ipad usb power adapter, that's what i did and worked like a charm

[bursty]

Ensure you are running the very latest distro and have run the updates to get the latest stuff (rpi_update etc) - there have been USB fixes in their that may help.

I downloaded the latest one of rasperrypi.org.

Make sure your power supply is up to the job, 1A should be enough, and its needs to be a decent supply that doesn't fade voltage as current increases.

It is 1.2A.

Make sure the uUSB cable you are using is decent quality - we have had quite a few reports like this that turned out to be dreadful quality USB power cables.

It is brand new from Element 14. I can't see why this wouldnt be sufficient.

[jamesh]

Ensure you are running the very latest distro and have run the updates to get the latest stuff (rpi_update etc) - there have been USB fixes in their that may help.

I downloaded the latest one of rasperrypi.org.

Make sure your power supply is up to the job, 1A should be enough, and its needs to be a decent supply that doesn't fade voltage as current increases.

It is 1.2A.

Make sure the uUSB cable you are using is decent quality - we have had quite a few reports like this that turned out to be dreadful quality USB power cables.

It is brand new from Element 14. I can't see why this wouldnt be sufficient.

Have you done an rpi-update?

[pluggy]

The USB power card is vastly over played on here, its a convenient excuse for what is more often than not issues with the Pi's USB implementation. I'm presently experimenting with an un-powered hub with a mouse, keyboard and a wireless adaptor plugged into it (pretty much breaks all the rules). It works fine on a 'B', the 'A' with everything swapped over gives all sorts of USB error messages during startup and winds up with nothing working. Thats after rpi-udpate running a kernel dated 1st May 2013. If it were a power issue, the 'A' would work better than the 'B' due to its much reduced power consumption.

I get a solid 5.17 volts across the test points with everything plugged in on the 'A'. I couldn't be bothered taking the 'B' out of its case to check it and since it worked there didn't seem much point. The 'B' is a latish revision 2 with 512MB of RAM. (not late enough to have Hynix memory). I had most success on the 'A' with the unpowered hub, using (shock, horror) an Apple keyboard itself with a built in hub, it didn't like stuff being plugged in through it (the 'B' didn't mind), but it did work with a wireless adaptor at the same time. I couldn't convince it to stretch to play with any of my mice though.

The type of hub has a big bearing on whether stuff works as well. All in all, its a lottery as to whether USB peripherals work or not and that varies on exactly which hub you're using and what other peripherals you have connected at the same time. One of my keyboards occasionally bounces keys, whereas it doesn't if its connected direct.

[jamesh]

The USB power card is vastly over played on here, its a convenient excuse for what is more often than not issues with the Pi's USB implementation. I'm presently experimenting with an un-powered hub with a mouse, keyboard and a wireless adaptor plugged into it (pretty much breaks all the rules). It works fine on a 'B', the 'A' with everything swapped over gives all sorts of USB error messages during startup and winds up with nothing working. Thats after rpi-udpate running a kernel dated 1st May 2013. If it were a power issue, the 'A' would work better than the 'B' due to its much reduced power consumption.

I get a solid 5.17 volts across the test points with everything plugged in on the 'A'. I couldn't be bothered taking the 'B' out of its case to check it and since it worked there didn't seem much point. The 'B' is a latish revision 2 with 512MB of RAM. (not late enough to have Hynix memory). I had most success on the 'A' with the unpowered hub, using (shock, horror) an Apple keyboard itself with a built in hub, it didn't like stuff being plugged in through it (the 'B' didn't mind), but it did work with a wireless adaptor at the same time. I couldn't convince it to stretch to play with any of my mice though.

The type of hub has a big bearing on whether stuff works as well. All in all, its a lottery as to whether USB peripherals work or not and that varies on exactly which hub you're using and what other peripherals you have connected at the same time. One of my keyboards occasionally bounces keys, whereas it doesn't if its connected direct.

Re: first line. As you well know there have been quite a number of cases where a inadequate USB cable has caused problems, so it's always worthwhile ensuring the cable is OK, which we have confirmed since it sounds like a good one purchased reputably. Get rid of all the other possibilities before blaming a driver problem, standard diagnostic practice. Not convenient excuse.

It's not a lottery, and if it is, it's well biased in favour of the user. Once again, can I ask that you do not make things out to be worse than they actually are. We know there are still some edge cases where USB is problematic. You don't need to keep going on about it. The way you put it sound like half the Raspi population is having problems. They are NOT- or this forum would be utterly swamped with problems. I would add, how many devices have you personally tried, how many hubs? Your experience is statistically insignificant I'm afraid. Just because you have problems, doesn't mean the whole user community is having problems. One swallow does not a summer make.

I've had to say this before, I'd rather not repeat it again.

[cyrano]

The fact that the USB ports are only "specced" for 100 mA is a deviation from the standard.

And the fact that many powered hubs supply power on the linkup port to the computer is a deviation from the standard too.

Neither is allowed by the USB specs. But the USB regulators don't care as long as they get their fees. That accounts for a lot of USB devices out there that behave badly.

And combined they will produce odd behaviour with some devices. But let's not forget a lot of stuff out there is weird. USB powered harddisks shouldn't even exist in my view. "Y" USB power cables neither.

When your hub's PSU has 5,15 V and the Pi has a supply that gives 4,95 V, you create a small current based on the 0,2 V difference, running from the hub to the Pi. It will not damage anything, but it will carry noise and spikes. And these do disrupt some functions in some conditions on some devices.

I've been doing some testing and most phone charger PSU's seem usable. But the mini USB to USB cables are very often not. In about 20 used PSU's tested, only 3 failed. On 7 cables tested, 5 failed. Resistance on these cables ran to almost 10 Ohms. That's a bigger problem than the PSU itself. And much harder to check if you don't know how to use a DMM.

I even found a couple of USB data cables that work with a keyboard and mouse, but not with HD's or webcams. I don't know why, haven't measured capacitance or stuff like that. And all this is OK for the tinkerer, but an average user who expects USB to just "work" might be in for a couple of surprises.

let's not forget we are dealing with a bare board, no external grounding scheme, no shielding. That doesn't help to keep things stable. And that's where the Pi has surprised me. It's relatively immune to radio and magnetic interference. But your peripheral stuff might not be.

[Gert van Loo]

The fact that the USB ports are only "specced" for 100 mA is a deviation from the standard.

If you read the standard very carefully you will read that it is NOT!
Most people think the USB has to supply 500mA. That is a myth.
If I recall correctly the standard says that it has to supply minimum 100mA (or was it 50mA? not important here)
Then if you want more you have to ask for that and the USB master MIGHT give you more, up to 500mA.
But it is not the standard output current.
In fact you will find that most Laptops can NOT supply that much and only a few desk top computers on SOME ports.
My latest Desktop PC has 12 USB ports so I should be able to draw a total of 6A out of it? No way!

[wirelessmonk]

I wanted to provide a contrast by comparison.

1x256MB RPi, 2x512's, a Trendnet powered 8 port hub and a powered DLink 7port hub. Wifi N and Bluetooth 4 dongles, keyboard and trackpad. Powered ports on both hubs peak at 1.5A. Using the powered ports to power the RPi too. Cable internconnects in some of the configurations are of questionable origin.

Not a single problem.

As ever. Your Mileage May Vary.

[pluggy]

Re: first line. As you well know there have been quite a number of cases where a inadequate USB cable has caused problems, so it's always worthwhile ensuring the cable is OK, which we have confirmed since it sounds like a good one purchased reputably. Get rid of all the other possibilities before blaming a driver problem, standard diagnostic practice. Not convenient excuse.

It's not a lottery, and if it is, it's well biased in favour of the user. Once again, can I ask that you do not make things out to be worse than they actually are. We know there are still some edge cases where USB is problematic. You don't need to keep going on about it. The way you put it sound like half the Raspi population is having problems. They are NOT- or this forum would be utterly swamped with problems. I would add, how many devices have you personally tried, how many hubs? Your experience is statistically insignificant I'm afraid. Just because you have problems, doesn't mean the whole user community is having problems. One swallow does not a summer make.

I've had to say this before, I'd rather not repeat it again.

The USB power issue is almost universally blamed for USB problems, which is why I've said its overstated. I know enough about electricity and electronics and have the test equipment (meter and 'scope) to be able to fathom power issues on my own gear, the problems I've been having with the Pi 'A' are most definitely not power related. And its not old software, the latest from rpi-update after I've done the full apt-get routine. The excessive power consumption of peripherals is almost always overstated. My own maesurements suggest that the only thing that will go over 100mA is USB powered hard drives. Keyboards and mice (or mine at least) don't go above a few tens of mA, My 'fancy' Microsoft Sidewinder X4 is only 55mA with the backlighting full up (this wasn't one of the 3 others I tried, its never worked on a Pi, I don't push my luck). My other keyboards don't exceed 15mA with the Caps lock and Numslock LEDs on (and those are the bulk of the current). All my wired mice consume around 10-15mA

How many people on here would say that a Wifi Adaptor, a keyboard and a mouse plugged into a bus powered hub all plugged into one USB port on a Pi will work ?. It does, but not on an 'A'. 200mA (ish) less current than a 'B' and and all the exactly same stuff I swapped over from the 'B' doesn't want to play. There's nothing to point the finger at other than the USB.

I've used 3 different keyboards, 3 different hubs (1 powered), 3 different mice and 2 different wifi adaptors. They all work on the 'B', and most of them have issues on the 'A' in various combinations with each other. I'll leave the webcams alone, the recent ones work, the old ones don't on the 'B', I though the 'A' was pushing it a bit. The latest software means my Microsoft VX800 works almost perfectly on a 'B' (odd mangled frame which I can live with).

[pluggy]

I wanted to provide a contrast by comparison.

1x256MB RPi, 2x512's, a Trendnet powered 8 port hub and a powered DLink 7port hub. Wifi N and Bluetooth 4 dongles, keyboard and trackpad. Powered ports on both hubs peak at 1.5A. Using the powered ports to power the RPi too. Cable internconnects in some of the configurations are of questionable origin.

Not a single problem.

As ever. Your Mileage May Vary.

Any model 'A's ?

[abishur]

Re: first line. As you well know there have been quite a number of cases where a inadequate USB cable has caused problems, so it's always worthwhile ensuring the cable is OK, which we have confirmed since it sounds like a good one purchased reputably. Get rid of all the other possibilities before blaming a driver problem, standard diagnostic practice. Not convenient excuse.

It's not a lottery, and if it is, it's well biased in favour of the user. Once again, can I ask that you do not make things out to be worse than they actually are. We know there are still some edge cases where USB is problematic. You don't need to keep going on about it. The way you put it sound like half the Raspi population is having problems. They are NOT- or this forum would be utterly swamped with problems. I would add, how many devices have you personally tried, how many hubs? Your experience is statistically insignificant I'm afraid. Just because you have problems, doesn't mean the whole user community is having problems. One swallow does not a summer make.

I've had to say this before, I'd rather not repeat it again.

The USB power issue is almost universally blamed for USB problems, which is why I've said its overstated.

Actually, the USB power issue is the *first* point we discuss in trouble shooting. That is to say when a problem is initially raised, the first place we go to is the power supply. We do it because in the very beginning 9 times out of 10 the power supply was the culprit, now we're down to 7 times out of 10 the power supply being the culprit, or at least adding to the issue at hand so we still keep it in the top 1-3 questions we ask when troubleshooting. I'm sorry if you feel like this is us trying to place universal blame for the USB problems on power supplies, but that assessment would only be true if (and only if) that was the end of the troubleshooting support and we sat around telling people "nope you're doing it wrong it's the PSU". However, that is *not* what we do! We start with the most likely, most common problem source, which is still power, and work outward from there.

I mean just look at the thread, James had already asked, had the PSU ruled out, and moved onto the next most likely culprit before you came in acting as if we were trying to push an agenda rather than getting needed data points

I know enough about electricity and electronics and have the test equipment (meter and 'scope) to be able to fathom power issues on my own gear, the problems I've been having with the Pi 'A' are most definitely not power related. And its not old software, the latest from rpi-update after I've done the full apt-get routine.

Awesome! At the same time, this isn't a thread you started and if you want to discuss your pi issues it needs to be in it's own unique thread rather than hijacking this one

[pluggy]

Awesome! At the same time, this isn't a thread you started and if you want to discuss your pi issues it needs to be in it's own unique thread rather than hijacking this one

Point taken, I've probably p*ssed James off enough. I'll try and behave.

[abishur]

Awesome! At the same time, this isn't a thread you started and if you want to discuss your pi issues it needs to be in it's own unique thread rather than hijacking this one

Point taken, I've probably p*ssed James off enough. I'll try and behave.

If you do start a thread to discuss differences in devices that work on one board but not the other, be sure to PM me the link, I would enjoy following that thread

[pluggy]

It has been brought up before by others, but it doesn't seem to generate much interest. I don't know how well the 'A' sells, if they only do a couple of hundred a month its insignificant. The 'A' would be ideal for what I want to do, but its getting stuff to work reliably with it. I've returned one as faulty because it was croaking with proven software / hardware (on the 'B' that is) only to find the replacement did exactly the same. Who'd have thought the lack of another hub (the built in one in the 'B') would cause issues. I can get a USB webcam that works reasonably well that is a lot cheaper than the expected camera module and that would go some way to buying the 'B' over the 'A'. I'll maybe stay with the 'B'.......

[bursty]

So after booting my Pi with only a HDMI cable and a wireless keyboard/mouse combo (Microsoft Wireless 800) I get the keyboard not picking up every stroke and doing random things.

After hearing so many good things about the Pi im pretty pissed it cant even power a keyboard and mouse.

When I plug in my powered hub and then plug the receiver into that, I then get spammed keystrokes, not picking up my keystrokes, spammed returns etc.

[jamesh]

So after booting my Pi with only a HDMI cable and a wireless keyboard/mouse combo (Microsoft Wireless 800) I get the keyboard not picking up every stroke and doing random things.

After hearing so many good things about the Pi im pretty pissed it cant even power a keyboard and mouse.

When I plug in my powered hub and then plug the receiver into that, I then get spammed keystrokes, not picking up my keystrokes, spammed returns etc.

Have you tried with a wired mouse and keyboard? Would be interesting to know if its specifically your wireless devices setup that is problematic; if so we can get one for Gordon to try to debug. I've used a wireless keyboard (Logitech one actually designed for the Wii) and it worked fine, so I'm guessing it's your particular devices.

And just to make sure - you are using the very latest distro from the download page (Wheezy Hardfloat -the recommended one), and have run all the updates to include the latest USB fixes?

[Burngate]

... im pretty pissed it cant even power a keyboard and mouse

Are you sure it can't?
The Pi can supply enough power only if it's being given enough on it's input; but if it's getting enough then it can give enough.

Power can be a problem ... but so can the USB subsystem.

To eliminate the first, you can buy multiple power supplies, and multiple leads, and try them all, or you can buy a meter and measure the volts across TP1-TP2

After that, if you've got a solid 5v across TP1-TP2 then it's not a power problem

[Burngate]

Interesting thread: http://www.raspberrypi.org/phpBB3/viewt ... 39#p343539

[pluggy]

Wireless keyboards and mouses(mice) often give problems on the Pi. and more often than not because of the USB subsystem, not because the Pi can't feed enough power to the bluetooth dongle (or similar, not all of them use bluetooth). If you haven't already I'd bring everything up to date with (sudo) apt-get update & apt-get upgrade. rpi-update (google it, it isn't standard) will possibly yield positive results. Its a test bed for the latest firmware and it may improve things.

[cyrano]

The fact that the USB ports are only "specced" for 100 mA is a deviation from the standard.

If you read the standard very carefully you will read that it is NOT!
Most people think the USB has to supply 500mA. That is a myth.

It's certainly not a myth for USB 3, as you can find on the USB.org site.

I did a lot of compliance testing and documentation when USB 2 was new. It was a requirement then. But a lot has changed since that time. I can't find anything about it, since all they seem to talk about is USB 3. Most links referring to USB 2 end in error 404's. Not nice.

If I recall correctly the standard says that it has to supply minimum 100mA (or was it 50mA? not important here)
Then if you want more you have to ask for that and the USB master MIGHT give you more, up to 500mA.
But it is not the standard output current.

If I understand correctly, that's for charging and new for USB 3. And only on ports that negociate power requirements. And if my perception is correct, less and less devices negotiate current.

In fact you will find that most Laptops can NOT supply that much and only a few desk top computers on SOME ports.
My latest Desktop PC has 12 USB ports so I should be able to draw a total of 6A out of it? No way!

That's how they make these things. Doesn't mean it is good. I regularly use USB devices that need 500 mA CLEAN power from USB, so I know how bad it is. But I wouldn't keep a laptop that isn't able to feed what I need. I just sent back three new laptops because they can't make wifi work without 50% dropped packets. Makes me wonder if nobody checks anymore...

Anyhow, it's not very important to this thread, nor to me. The point was that USB is a strange beast and not all of USB's faults can be blamed on the Pi. I have loads of USB stuff that doesn't work on Windows, or Linux, or OSX, yet it's not broken. It's just the manufacturer that doesn't seem to care. And the users are used to throwing stuff away. Sad, very sad.

[Mobius]

Just to add a data point, I have an early Pi that has (actually had) polyfuses on the input and on both USB ports. The power issues drove me crazy. Even with a powered hub I got inconsistent behavior with a keyboard, mouse and wifi dongle plugged in. Shorted across the USB polyfuses and bypassed the input polyfuse with a glass fuse and the problems all went away (I also have an HDMI to VGA adapter being powered). I now run all of my USB devices on the same hub as before but without the need to power it.

[jojopi]

I did a lot of compliance testing and documentation when USB 2 was new. It was a requirement then. But a lot has changed since that time. I can't find anything about it, since all they seem to talk about is USB 3. Most links referring to USB 2 end in error 404's. Not nice.

The USB2.0 and USB3.0 specs are both freely available from the same page: http://www.usb.org/developers/docs/

Both require that devices must power up and provide configuration information on 100mA, and cannot draw more current than that unless switched to a high-power configuration by the host. (Or connected to a charger, which has its D+ and D- tied together.)

That is essential so that plugging a high-power device into a bus-powered USB2.0 hub does not brown out all the other devices on the hub. Of course, it is also widely ignored, so that plugging a 2.5" HDD into a bus-powered hub will indeed brown out the whole hub.

[DirkPrefect]

I know from experience that the some of the power supplies from Element 14 (newark or mcm) designed for USA use don't produce the power needed to be used with a PI. These are the wall wart with cheap thin attached cable that ends in the uUSB connector. The china made model Bs (256MB version and 512MB versions with UK made board and made in china sticker on top) use much more power to operate than the Full UK version model B (no made in china sticker). Each of these was ordered from Element 14 (newark and MCM) I was able to power the UK made model B from the MCM labelled power supply as long as I kept the current draw down to reasonable levels. The apple ipad 10W, adafruit usb model, and nexus 7 chargers have all worked well with all 6 of my current PIs even with overclocked processors.

Depending on the wireless keyboard mouse combo, it is very possible for 2.4Ghz wifi and phones to cause similar issues with the devices. Also the cheaper (non-branded non-bluetooth) units are known for drawing lots of current on the wireless transciever. A basic wired keyboard and mouse are handy to have for trouble shooting in general.