USB - the Elephant in our Room

[hermanhermitage]

Then there are devices in combination with what other devices and what engineering changes were/were not present on the "test" device. A pretty daunting task....

My experience runs counter to this - you lock in a fixed combination of devices for the less experienced users and tell them caveat emptor beyond that - see for example how Dell or Apple configure their devices. You are talking large enough volumes now to get a Logitech or equivalent to partner.

The idea being you shut down the noise from less experienced users or those who probably arent ready to fiddle with unsupported or untested combinations.

(Quick Edit: Just be clear I'm talking about for the less experienced folks who just know 'they need to get a pi' and want to run a few games and a little bit of programming - *NOT* the hard core geeks and makers...)

[MaxK1]

That kinda runs counter to how the Rpi was intended to be used- plug in whatever keyboard/mouse you have from an old PC and let the kids have at it.... I suppose people are buying "bundles" and those could be tested more thoroughly. But plug in a counterfeit HTC/Kindle/I-? charger and all bets are off...
Sigh. Thankless task. Keep up the good work, guys!

[LenReinhart]

I received a 2 Amp switching power supply with a Rosewill 7 port hub. The hub didn't work out, but the power supply is great. I use a Kensington 4 port hub with the 2 Amp supply and feed my pi with it as well as hooking up my keyboard, mouse and 16G USB stick. I have never had a power or USB problem with this setup. I also have used the 2 Amp switcher from my Nexus 7 and it works great too.

I just got a 512MB pi and am using it with a Motorola Lapdock. It all works great. I had already modified the cables so the USB fed both the power and data so I have two open USB ports on the Lapdock for memory sticks and wireless, although I have not been able to get the wireless I have to work yet. I overclock my pi in turbo mode and have not seen any memory corruption.

I think the answer to giving solid systems to young people is to thoroughly vet the components and have recommended sets of hardware. I have my doubts about one amp supplies, especially using linear regulators and wireless.

[Dweeber]

meanwhile we are forced to reply on community involvement to document what does and doesn't work. After all, there's lots more people out there than in here, with access to a vast array of USB equipment.

I always equated the green color of your user ID on the forum as being an indication of god like capabilities beyond us mortals. Are you saying that you can't do the same as multitudes of us mere mortals in everything you do?

[jamesh]

meanwhile we are forced to reply on community involvement to document what does and doesn't work. After all, there's lots more people out there than in here, with access to a vast array of USB equipment.

I always equated the green color of your user ID on the forum as being an indication of god like capabilities beyond us mortals. Are you saying that you can't do the same as multitudes of us mere mortals in everything you do?

I am completely unable to figure out what women mean when they talk too. Godlike powers are a real let down.

[MaxK1]

Ooooo - not when walking on water, I hope....

[piglet]

I am completely unable to figure out what women mean when they talk too. Godlike powers are a real let down.

Darn it! You say there's meaning in there somewhere?!

/me runs from teh wrath of Liz, giggling maniacally

[insanityideas]

Would it be useful to develop a little (?python?) script that collected the enumerated USB devices and details about the pi (serial number, OS version, revision, date) asked the user to say if they were working or not and then automatically send that off to the wiki, where it could be automatically (or mandraulically) compiled into a list of known working devices.

Would require some co-operation from the wiki people and foundation to distribute it as part of core Raspian, but if it was super easy todo then it would really increase the list of known good and known bad devices. A bit like how windows sends crash dumps to microsoft, only for good events as well! Although this would be opt-in with limited user involvement... less effort on their part the more successfull it would be.

Would this sort of crowdsourced data be of any use in fault diagnosis (or could be added to so it is useful). Might help characterise more generally what Pi's are being used for and focus the limited development resources in particular directions.

Thoughts??

[Burngate]

meanwhile we are forced to reply on community involvement to document what does and doesn't work. After all, there's lots more people out there than in here, with access to a vast array of USB equipment.

I always equated the green color of your user ID on the forum as being an indication of god like capabilities beyond us mortals. Are you saying that you can't do the same as multitudes of us mere mortals in everything you do?

Green means Priest, Shaman, Soothsayer or Seer
Blue means Snake-oil Purveyor.
For the True Gods see Red

[MaxK1]

Insanityideas:

In theory a good idea, but with so many users still believing that the 5V/1.2A sticker on their "PSU"
actually means 5V/1.2A 100% of the time, you will get a lot of devices listed as "Not working", when in fact, they work fine. I would think that a UG meeting where LOTS of problem devices could show up and be tested on a "Known Good Pi + PSU" might debunk a few myths and users can get a basic understanding of Volts, Amps and Ohms (Those little crawly things) if they don't fully understand them.
Or more likely, correct some common mis-understandings...

[p4trykx]

I think it's very hard to determine if something works and cover all the combinations(hub+device). For instance my 3G modem(SW 307) works most of the time but when I set up a logging and was sending it through 3G network I turned out it was crashing few times a day. I don't know if it's hub related or modem related. Also some bad behavior unveils only under heavy load.
Almost all my USB devices (except wired mouse and keyboard) at home have issues working stable on Raspi. On the other hand I used them with my router working 24/7 without any problems.

I firstly reported my wireless Logitech Keyboard as working. But then I discovered under heavy load it was experiencing sticky keys.

[MaxK1]

It can be if you have a wonky setup to begin with....

[p4trykx]

Of course I ruled out power problems. I have PSU form RS component's and also tried with another 2A one from Kindle Fire. Soldered w wire over USB polyfuses, measured the voltage and done all other voodoo....
However there is some progress, previously 3G modem was not working at all. Communicating over ttyUSBx was very slow. Now I'm down to few crashed a day so I'm happy

[obcd]

And what would be the definition of a "known good Pi" and "known good supply"
People have tested with pc supplies capable of delivering like 10 Amps on their 5V rail, and are still reporting problems.
The foundation itself admits that the usb driver is having issues. It's just unclear in what combination.
And now I need to read again that peoples supplies are no good and their setup is no good and they don't understand ohms law well enough to get their Pi usb running. Not to mention half of the usb devices on the market that are no good.
It's not like people are connecting 7 usb devices to their Pi's. It are the basics like a keyboard, mouse and memory stick you expect them to connect.
Supply voltage can be an issue, but it's not the answer to every problem.

[MaxK1]

Of course it isn't, but it seems to be a major one. If I knew for sure that a given users power was NOT an issue, I'd dig in to the next level. Unfortunately, not everyone "gets" it when it comes to power...
But I'm not too inclined to even start looking until a power issue is eliminated. That includes polyfuses,
10 Feet of 40 gauge wire powering the device, etc.

[insanityideas]

Taking a turn for the positive... the proposed tool could also record all the stuff that works properly... I suggested it in reference to people wanting a "known good" list and thought it would be a better way of compiling a big list rather than expecting people to go edit a wiki... compared with click.. yes... yes.. sent.

Things can be broken for all sorts of reasons... at least we would be able to get more data about what works and doesn't... even if sometimes its flaky power adapters or whatever skewing the results it still builds a picture of where the problems lie.

[japie]

It's not like people are connecting 7 usb devices to their Pi's.

I have 7 smargo smartreaders attached so there are people out there doing that...
Indeed power can be an issue but it would be short-sighted to blame it for all usb trouble written in this forum.
A list of working and malfunctioning usb devices sounds like a very good idea.

[Lob0426]

It's not like people are connecting 7 usb devices to their Pi's.

I have 7 smargo smartreaders attached so there are people out there doing that...
Indeed power can be an issue but it would be short-sighted to blame it for all usb trouble written in this forum.
A list of working and malfunctioning usb devices sounds like a very good idea.

There is a list of working and incompatible devices. I have added devices to the appropriate list also. I was also able to add new categories. So this is the best place look. If you have stuff you would like to add, but are not really sure how to do it. Post it/them in the forum. I am sure someone will add them to the Wiki for you.

Here is the link to the wiki for verified peripherals:
http://elinux.org/RPi_VerifiedPeripherals

[insanityideas]

There is a list of working and incompatible devices. I have added devices to the appropriate list also. I was also able to add new categories. So this is the best place look. If you have stuff you would like to add, but are not really sure how to do it. Post it/them in the forum. I am sure someone will add them to the Wiki for you.

Here is the link to the wiki for verified peripherals:
http://elinux.org/RPi_VerifiedPeripherals

I think you missed my point, I am talking about a tool that automatically updates a database, by using the unique serial number of the pi you can stop it getting spammed with the same peripheral, it would automatically work out known good peripherals based on achieving a pre-set number of positive reviews without too many negatives.

The reason why I would need help (other than less than stellar coding skills):

• The database would need to be hosted on the wiki, and have ability to publish to it (or another page).
• The tool would need to be distributed into raspi-config or start menu of default raspian distro for it to gain critical mass of usage.

Neither of those things are within my influence.

A less sophisticated starting point would be putting the script on the wiki as a standardised way of getting data, but even then you need to send the data to a central point where someone can interpret it.

The tool could advise on things like an appropriate power supply where problems are encountered, perhaps even ask for details of the power supply.

[MaxK1]

I'd be in real trouble if I went by that list "as is" - Good thing I didn't check there first - I have 3 of the "non-working" or "problem" devices, all connected to a pi and they work just fine. Microcenter 4G Class 4 SD cards (Several of those to choose from), Trendnet TEW-424UB WiFi and a Dell SK-8115 keyboard. I don't know why they earned a place on the "wall of shame", but I imagine because whoever reported them as "broken" made some erroneous assumptions about the rest of his/her system and/or abilities. I also have a 5V/6A REGULATED supply that puts out 5.1V and powers both a hub and the pi (through the GPIO header) HDD is powered separately. I had nothing but trouble using (borrowed) phone chargers (Some which actually had a connector that fit properly!)

Going a bit further than Volts/mA - how much RF hash is put out by some of those cheap and nasty "replacement" phone chargers? (I would imagine that the guys building the counterfeit chargers don't bother with annoying little details like getting them certified) Some of them put out a substantial RF signal to damn near Daylight - which is potentially Bad News(tm) if you are trying to get a WiFi/BT device to work... So without knowing the test environment, including the testers abilities (or lack of same), it's kinda difficult to tell how valid a problem device report is. Easiest thing to suggest is try a
different PSU, take it from there and see where it leads.

[thradtke]

[...] I am talking about a tool that automatically updates a database, by using the unique serial number of the pi you can stop it getting spammed with the same peripheral, it would automatically work out known good peripherals based on achieving a pre-set number of positive reviews without too many negatives.

You're going to make a science out of a bug .

Likely, we'll see in the next few month a solution in software or a new SoC. If absolutely nothing moves, the base of knowledgeable persons bearing such a project will erode to nigh on zero.

[obcd]

The Pi is suposed to be a tool for educational purpose. So, third world countries (among others) have a cheap platform to start learning programming. The idea is they take an usb keyboard, mouse and cheap phone charger they have lying around, they connect it and they can start to work.

While automatically generated databases and compatibility lists are great ideas, they aren't very helpfull in achieving the above goal. If I have to go shopping for a Pi certified keyboard, mouse and supply, the low cost factor of my platform is quickly dissapearing.
mice and keyboards are low speed hid devices, and hid is a standard. The same is true for usb mass storage devices. If they get enough voltage, they should simply work.

RF coming out of a charger shouldn't be a problem. The expected output of such a device is DC, so a simple lowpass filter being a couple of capacitors and a coil can do the trick.
Even a ferrit bead around the power cable helps a lot.

If devices appear on the list that work for some people and not for others, we are facing an even bigger problem, since apparantly at that moment working or non working is like playing the lottery.
In my opinion, if keyboard x isn't working, and keyboard y does work, we can put x on the list of incompatible devices. But, if a good supply is used (no idea how to define a good supply in case of the Pi) keyboard x might also work. So, should it be on the list or not?
A supply needs to be able to deliver a stable DC voltage. A good supply does this from no load till full load conditions. A stable DC voltage is a voltage that isn't containing much ripple. (An issue you might be unable to measure without a scope)
For stable operation, the Pi seems to need a voltage between 4.85 and 5.25V this would mean a 5V supply with a deviation of maximum -4 to +5%
What other magical power supply parameter am I missing? Without knowing it, it's hard to order a known good supply for the Pi. Also be aware that 5 identical supplies not necessairily will produce the same voltage all 5. So, yours might work and mine might not.

[LenReinhart]

I think it is important how a supply responds to a fast change in load. That is why some people are putting caps across their supplies, they can't take the transients. The switching two amp supplies that I have are solid enough that I have never had a problem. I know for sure that some of the phone chargers are inadequate. I am looking at a Motorola supply that is rated at 550 ma, that while it charges my phone fine, I would never attempt to power a pi with it.

Len

[MaxK1]

[quote="obcd"]
RF coming out of a charger shouldn't be a problem. The expected output of such a device is DC, so a simple lowpass filter being a couple of capacitors and a coil can do the trick.
Even a ferrit bead around the power cable helps a lot.

I'm not talking about RF getting into the Pi (that wouldn't be a Good Thing either) I was thinking more RF getting into the surrounding devices (mainly, but not limited to, WiFi and BT) I sometimes wonder if some of these PSU's started out life as transmitters...

As you say, the _expected_ output is DC.

[LenReinhart]

If it is a switcher there will be a certain amount of hash. Many of the wall wart types are just poorly rectified transformers, I have seen some with ripple of several volts. The ones with USB connections rated at an amp or better are probably the best bets. The other type is the supplies for the USB hubs that are an amp or better. A lot of the phone supplies are relying on the battery in the phone to act as a large capacitor. A four port hub can supply 500 mah to each port, While I know all USB devices don't draw that much, it is never a good idea to run close to the capacity of your power supply. It invites brown outs which the pi will not tolerate (and should not have to or be expected to).