JonB
Posts: 220
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Been away for a while - still got USB power issues?

Sun Feb 09, 2014 10:51 am

Hi

I've been away for quite a while, and one reason was that the old Model B that I have (256Mb) always had problems with the USB. I built a "Raspberry Pi laptop" using a Motorola Atrix LapDock but the keyboard and mouse kept disconnecting, and there was a very long discussion about problems with the USB implementation on the board, and in the drivers. I decided to leave it in the hope that a software solution could be found. Now, I can't find the thread. :(

My question is: Can anyone recall this, and has it been fixed? If so, do I need a new Pi, or can I get away with modifying the old one?

Many thanks

JonB

jamesh
Raspberry Pi Engineer & Forum Moderator
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Re: Been away for a while - still got USB power issues?

Sun Feb 09, 2014 10:54 am

You should the latest firmware works fine with the majority of USB devices. There have been quite a few fixes in that area, and there are more to come to try and help with the last remaining issues. But most USB devices should work fine. There are some issues with some USB sound dongles, and some that use a particular form of transfer (I'm not entirely familiar so take that with a pinch of salt), but certainly keyboards and mice should be fine.
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klricks
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Re: Been away for a while - still got USB power issues?

Sun Feb 09, 2014 3:10 pm

In addition to firmware fixes. There was a hardware change on the Rev 2 (512MB) boards. The Rev 1 (256MB) boards had fuses (F1 and F2) at the USB ports which limited the power out the USB ports and caused higher power devices to drop out.
The Rev 1 boards can be modified by removing the fuses F1 and F2 and soldering a wires across the pads.

To get updated firmware use these 2 commands:
sudo apt-get update
sudo apt-get upgrade
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

JonB
Posts: 220
Joined: Tue Nov 29, 2011 9:26 pm

Re: Been away for a while - still got USB power issues?

Sun Feb 16, 2014 5:25 pm

Well.. amazingly enough, I found that with the two fuses replaced with links, my old Raspberian installation was much more stable, but when I loaded the NOOBS distro and installed Debian it is as bad as ever. XMBC just locked up.

Seems to have gotten worse, not better (or the repositories have regressed somehow).

jamesh
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Re: Been away for a while - still got USB power issues?

Sun Feb 16, 2014 9:33 pm

Odd. I've got a pretty old 256 Model B, and it's works fine, unmodified. I wonder if there is another issue at play - have you checked the voltage on the test points to ensure you power supply is up to the job?
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JonB
Posts: 220
Joined: Tue Nov 29, 2011 9:26 pm

Re: Been away for a while - still got USB power issues?

Tue Feb 18, 2014 9:23 am

Hi James

No tests yet, but it's a "Raspberry Pi Laptop" with a Atrix Lapdock, wired per veryevil's instructions. It appears to be working well once I'd replaced the fuses, and that was with an old Raspberian version. I tried to apt-get update but it looked like it couldn't reach some of the repositories, which I put down to them being moved. So I reflashed the card with NOOBS.

I selected Debian and XMBC and let it do it's thing. Gotta hand it to the developers, it's pretty slick. But once booted it became apparent that the old USB issues were back. So from this perspective - the only thing changed was the software - you can see why I might be disinclined to blame the hardware.

I'll check it anyway. Where are the test points? It's an early model B (one of the second batch I believe) with 256megs of memory.

Regards

JonB

jamesh
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Re: Been away for a while - still got USB power issues?

Tue Feb 18, 2014 9:40 am

Test between tp1 and tp2 - voltage should be at least 4.75 IIRC.

What USB devices are you using, because I have heard of any issues with mice and keyboards for over a year (except high power ones ie > 100mA which is to be expected)
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JonB
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Joined: Tue Nov 29, 2011 9:26 pm

Re: Been away for a while - still got USB power issues?

Tue Feb 18, 2014 10:51 am

Just the Lapdock. And occasionally an EDIMAX wifi dongle, though it is connected to one of the Lapdock's USB ports, so should be powered by the Lapdock (in fact, so should the keyboard / trackpad).

Thaddy
Posts: 174
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Re: Been away for a while - still got USB power issues?

Tue Feb 18, 2014 11:13 am

What power draws the lap dock? What power can the power supply of the lap dock supply stably to the pi and what is connected directly to the pi without its own power? And does it do what it says on the sticker? Get your multimeter out (or better a scope, but a simply multimeter would do) and measure.

I have several Pi''s old and new, only B's, and after initial problems I made sure of a power supply that is well over dimensioned. (>= 1.5). Problems go away. The only recurring problems I have are on travel: the pi is very sensitive to ripple coming through from the mains. Your power supply should be able to filter that out. Maybe someone from the hardware guru's could shine a light on that?

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