Featured Articles
Announcing Pi
Technical Specifications
Raspberry Pi FAQs
Win a Pi
Raspberry Pi Wishlist
Actions
Forum Thread Details
  • Replies 22 replies
  • Subscribers 708 subscribers
  • Views 5523 views
  • Users 0 members are here
Related

USB device connect resets 512M Raspberry Pi (most USB devices).

e14 Contributor

Hi,

 

I got my batch of 3 brand-new 512M Raspberry Pi-s today (hardware revision "000f" according to /proc/cpuinfo). Every single one of them exhibits the same instability: They reset when I connect certain USB devices. If I have such an offending USB device connected on power-on and leave it in, it will work just fine. Which means that hot-plugging USB devices does not work - a critical bug.

 

I have a couple of USB devices that I can connect without resetting a running 512M Pi:

 

* A SanDisk Cruzer Micro 16 GB memory stick.

* A handful of non-descript memory sticks (give-away advertising gifts from various vendors).

* My USB keyboard.

 

But every single time that I plug any of the following devices into a 512M Pi it resets:

 

* D-Link N Nano Wi-Fi dongle DWA-131.

* Kingston Data Traveller II, 2 GB memory stick.

* An old IBM 64 MB memory stick.

* A pair of USB-powered loudspeakers (speakers with a mini-jack and an analog built-in amplifier powered by 5V USB).

 

I suspect that the USB power surge when an offending device is connected and powers up, is causing the Pi to reset. This did not happen on a previous revision of the Pi - I have three older 256M Pi's and they can all have all of the above USB devices hot-plugged without resetting (as you would expect).

 

The power rail on the 512M Pi's USB port is quite dirty. If I power my USB loudspeakers from a 512M Pi's USB port then I have just as much background noise as I have sound. The noise sounds like power supply switching noise, a 2-4 kHz steady tone with high-frequent chirps as soon as there is activity, e.g. the SD card is active. This leaves the audio output completely unusable. If I do the same setup on a 256M Pi there is still too much background noise for comfort but it is clearly less than on a 512M Pi. If I power the USB loudspeakers from elsewhere, e.g. my laptop, and connect the loudspeakers to the Pi's audio jack then the sound is fine - the noise level is at least low enough for casual listening.

 

I have two different types of 1000 mA 5V power supplies that I have tested with. There is no difference in behavior. I have even tried to buffer the on-board 5V by connecting a flat-ribbon cable to the P1 connector and then, via the ribbon cable wires, connect a 4700 uF capacitor across 5V and GND (pin 2 -> pin 6). No effect.

 

I have seen a report on thermal instability with the new 512M Pi's [1] but that issue is not seen here. I have left one of the 512M Pi's running for 3.5 hours straight without any problems - this one was idling and was not overclocked. I then overclocked it to max "Turbo" mode, re-booted, and started a python script that burns 100% CPU. The /sys/class/thermal/thermal_zone0/temp reported 45 degrees C (45000 raw number) when I started the script and stabilized at 53 degrees C after a minute or so. I left it running for more than 20 minutes straight - no problems.

 

[1] http://www.raspberrypi.org/phpBB3/viewtopic.php?f=28&t=22281&p=215444

 

There has also been a report on a bad USB controller connection [2]. We can rule that out. The issue occurs with specific USB devices and cannot be triggered by mechanically exciting the USB connector. Plus, it is the same pattern on all 3 boards.

 

[2] http://www.element14.com/community/message/64061

 

Unfortunately this sounds like an RMA on all three boards. Please advise me on how to proceed and when I can expect a new batch of 512M Pi's where the USB interface is stable again.

 

  Kind regards

-- Jan Holst Jensen

Parents

  • Here's a new thread chez RasPi: Raspberry Pi Reboots on inserting a USB device.  In the third comment, mahjongg says:

    Don't hot plug USB devices directly into the PI, if you must hot plug plug into a hub instead!

     

    Its called "the rush in current problem", and it makes that the current PI itself is non "hot pluggable", note that the revision 1 PI was hot pluggable, as the two polyfuses prevented any rush in current because the fuses had a non zero resistance. But in the current board there is literally zero resistance between the PI's 5V supply, and any USB device you plug in, that means that if you plug in any USB device with empty power decouplers, (which act as a complete short for a very small time) then you are actually simply shorting the 5V when you plug [the] USB device in...

    As the current PI only has two ports normally there is no need/possibility to hot plug anything in anyway, (without a hub) as the two ports are reserved for a mouse and a keyboard, unless you want to hot plug the keyboard. If you want to plug anything in beyond that you would already use a hub, and as said, you can hot plug safely into a hub.

    So there's the semi-official answer.  The rev 2 RasPi's USB ports look like standard USB ports, but aren't because they fail USB's fundamental hot-swappability requirement.

Reply

  • Here's a new thread chez RasPi: Raspberry Pi Reboots on inserting a USB device.  In the third comment, mahjongg says:

    Don't hot plug USB devices directly into the PI, if you must hot plug plug into a hub instead!

     

    Its called "the rush in current problem", and it makes that the current PI itself is non "hot pluggable", note that the revision 1 PI was hot pluggable, as the two polyfuses prevented any rush in current because the fuses had a non zero resistance. But in the current board there is literally zero resistance between the PI's 5V supply, and any USB device you plug in, that means that if you plug in any USB device with empty power decouplers, (which act as a complete short for a very small time) then you are actually simply shorting the 5V when you plug [the] USB device in...

    As the current PI only has two ports normally there is no need/possibility to hot plug anything in anyway, (without a hub) as the two ports are reserved for a mouse and a keyboard, unless you want to hot plug the keyboard. If you want to plug anything in beyond that you would already use a hub, and as said, you can hot plug safely into a hub.

    So there's the semi-official answer.  The rev 2 RasPi's USB ports look like standard USB ports, but aren't because they fail USB's fundamental hot-swappability requirement.

Children
  • in reply to johnbeetem

    John Beetem wrote:

     

    Here's a new thread chez RasPi: Raspberry Pi Reboots on inserting a USB device.  In the third comment, mahjongg says:

    Don't hot plug USB devices directly into the PI, if you must hot plug plug into a hub instead!

     

    Its called "the rush in current problem", and it makes that the current PI itself is non "hot pluggable", note that the revision 1 PI was hot pluggable, as the two polyfuses prevented any rush in current because the fuses had a non zero resistance. But in the current board there is literally zero resistance between the PI's 5V supply, and any USB device you plug in, that means that if you plug in any USB device with empty power decouplers, (which act as a complete short for a very small time) then you are actually simply shorting the 5V when you plug [the] USB device in...

    As the current PI only has two ports normally there is no need/possibility to hot plug anything in anyway, (without a hub) as the two ports are reserved for a mouse and a keyboard, unless you want to hot plug the keyboard. If you want to plug anything in beyond that you would already use a hub, and as said, you can hot plug safely into a hub.

    So there's the semi-official answer.  The rev 2 RasPi's USB ports look like standard USB ports, but aren't because they fail USB's fundamental hot-swappability requirement.

     

    What a shame. I run all my Pi-s headless and so have both "USB" ports free. It's only natural to want to plug in a USB memory stick, but that is too dangerous with the current board layout.

     

    Thanks for digging this up, John.

     

    Cheers

    -- Jan