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Pi 4 USB Current support

J Mathieson
 

I have fried a Pi 4 the other day when I had too many devices plugged in.   I have a new PI on the road and need all the devices connected but without over drawing current on the  onboard USB hub. 
1. Is there a known current limit on the Onboard USB hub

2. Will the Pi4 or Pi3 support a powered external usb hub. 

Thanks in advance
John AC8JW

 



On Fri, Jun 5, 2020 at 10:01 AM J Mathieson <ruteuser1@...> wrote:


2. Will the Pi4 or Pi3 support a powered external usb hub. 


Yes.

--
John D. Hays
Kingston, WA
K7VE

 

J Mathieson
 

I am implementing an amateur radio project that requires a device that allows the Pi to connect to my radio and USB Sound Card to provide audio in and out.  Connecting all these devices I suspect is what toasted my Pi.   So will try a Powered hub to relieve the Pi  

Thanks

David Ranch
 


Hello John,

I have fried a Pi 4 the other day when I had too many devices plugged in.

Define "fried".  You mean it smoked and it's 100% dead?  Maybe the SD card got corrupted?  The truth here is that you really shouldn't be able to electrically damage a device via a USB bus due to too much current draw.  Yes, crash the Pi would absolutely happen and maybe corrupt the file system on the uSD card but that should be the extent of it.


I have a new PI on the road and need all the devices connected but without over drawing current on the  onboard USB hub. 
1. Is there a known current limit on the Onboard USB hub

It's well documented that *ALL* versions of Raspberry Pis cannot provide a lot of power to USB devices.  Google it.


2. Will the Pi4 or Pi3 support a powered external usb hub. 

Yes, this has been supported since day one and it's the recommended solution from the Raspberry Pi foundation.

--David
KI6ZHD

N5XMT
 

Shouldn't have fried it.  The Pi can support up to 1.2A via USB.  The USB power is protected by PolyFuses, worst case, if it was current load, is it should have just popped the PolyFuse.  The rest of the Pi should still work.  And the PolyFuses reset themselves after a bit with no load.


On Fri, Jun 5, 2020 at 10:01 AM J Mathieson <ruteuser1@...> wrote:
I have fried a Pi 4 the other day when I had too many devices plugged in.   I have a new PI on the road and need all the devices connected but without over drawing current on the  onboard USB hub. 
1. Is there a known current limit on the Onboard USB hub

2. Will the Pi4 or Pi3 support a powered external usb hub. 

Thanks in advance
John AC8JW

Ray Wells
 

Does the RPi still use Polyfuses? My first two model B have them (bypassed by me) but my later model B doesn't. Maybe I'm looking in the wrong places but I can't find evidence of the polyfuse still being used. Does anyone have a definitive answer to the question?

Ray vk2tv

On 6/6/20 5:17 am, N5XMT wrote:
Shouldn't have fried it.  The Pi can support up to 1.2A via USB.  The USB power is protected by PolyFuses, worst case, if it was current load, is it should have just popped the PolyFuse.  The rest of the Pi should still work.  And the PolyFuses reset themselves after a bit with no load.

On Fri, Jun 5, 2020 at 10:01 AM J Mathieson <ruteuser1@...> wrote:
I have fried a Pi 4 the other day when I had too many devices plugged in.   I have a new PI on the road and need all the devices connected but without over drawing current on the  onboard USB hub. 
1. Is there a known current limit on the Onboard USB hub

2. Will the Pi4 or Pi3 support a powered external usb hub. 

Thanks in advance
John AC8JW

N5XMT
 

I stand corrected.  Just went and searched the Pi forums, and the Pi 4 doesn't have the USB polyfuses.  +5 on the USB connectors goes direct to the +5V on the GPIO pins.


On Fri, Jun 5, 2020 at 3:03 PM Ray Wells <vk2tv@...> wrote:
Does the RPi still use Polyfuses? My first two model B have them (bypassed by me) but my later model B doesn't. Maybe I'm looking in the wrong places but I can't find evidence of the polyfuse still being used. Does anyone have a definitive answer to the question?

Ray vk2tv

On 6/6/20 5:17 am, N5XMT wrote:
Shouldn't have fried it.  The Pi can support up to 1.2A via USB.  The USB power is protected by PolyFuses, worst case, if it was current load, is it should have just popped the PolyFuse.  The rest of the Pi should still work.  And the PolyFuses reset themselves after a bit with no load.

On Fri, Jun 5, 2020 at 10:01 AM J Mathieson <ruteuser1@...> wrote:
I have fried a Pi 4 the other day when I had too many devices plugged in.   I have a new PI on the road and need all the devices connected but without over drawing current on the  onboard USB hub. 
1. Is there a known current limit on the Onboard USB hub

2. Will the Pi4 or Pi3 support a powered external usb hub. 

Thanks in advance
John AC8JW

Suryono Adisoemarta
 

The radio part should not pull power off the Rpi board. The sound card is fine directly plugged to Rpi.
This is my setup on my Rpi-based satgate that has been working fine for months.

73 de Yono YD0NXX

On Jun 6, 2020, at 1:17 AM, J Mathieson <ruteuser1@...> wrote:

I am implementing an amateur radio project that requires a device that allows the Pi to connect

N3RDR
 

Why shouldn’t power be connected? I am about to do that very same thing. I is very low power though.

Sent from my 📲

On Jun 5, 2020, at 9:23 PM, Suryono Adisoemarta via groups.io <yono_adisoemarta=yahoo.com@groups.io> wrote:

The radio part should not pull power off the Rpi board. The sound card is fine directly plugged to Rpi.
This is my setup on my Rpi-based satgate that has been working fine for months.

73 de Yono YD0NXX
On Jun 6, 2020, at 1:17 AM, J Mathieson <ruteuser1@...> wrote:

I am implementing an amateur radio project that requires a device that allows the Pi to connect


John Mathieson
 

KI6ZHD, I made the assumption that my overheated usb soundcard had wrecked the board.  But maybe not.  I will reflash a card and see what happens.    More to follow  Thanks much

David Ranch
 


Hello John,

You never said what "fried".. now you're saying it was just the soundcard?  If you turn on your raspberry pi without an SD card, do you see the Rainbow color display?

   https://www.raspberrypi.org/forums/viewtopic.php?t=164372

--David


On 06/06/2020 06:27 AM, John Mathieson via groups.io wrote:
KI6ZHD, I made the assumption that my overheated usb soundcard had wrecked the board.  But maybe not.  I will reflash a card and see what happens.    More to follow  Thanks much

J Mathieson
 

Reflashed the card and behold, it worked!  Learned something new.  I suspect my old usb soundcard was the culprit so that has been replaced.  Thanks to all who replied. 

73
AC8JW

J Mathieson
 

David I did see the rainbow.  I have trashed other  Pi's though by the GPIO pins.   I made a wrong assumption.    Lesson learned.