F1/F2 polyfuses gone

For those of you wanting the executive overview:

jbeale wrote:I just received my 2nd R-Pi, this one from stock (yay MCM Electronics) which took just a week to ship from Ohio to California. I was pleased, but surprised to see that the USB fuses F1, F2 are now just 0-ohm jumpers (photo below). I was able to confirm they measure less than 0.1 ohms. Is this the new standard going forward?

by Burngate

You've obviously recieved a Chinese pirate copy - it won't have all the features a proper Pi would have, such as not working with some keyboards, and the like.

by eben » 25 Aug 2012 10:34

Yes. After seeing how many people have decided to modify their boards with zero-ohm links, and having done some safety and reliability testing, we've decided that the best course of action is to remove the USB fuses from the design. Right now they're linked out, but on a subsequent board revision the pads will be removed entirely.

by liz » 25 Aug 2012 10:37

And I'm impressed someone noticed so quickly!

From Me Peg: Unlike on this Forum, I do not read every little thing on the org forum. . . BUT . . . is it just me or does this seem kind of sneaky? Or to put it another way. . . what happened to the "Open" in the open software/hardware world? Or did I miss the instructions on what to do with the two pi's I now own to make them more stable? No suggestions on buying the beagleboard Morgaine!

> is it just me or does this seem kind of sneaky?

Also makes you wonder what other unannounced changes

have been made.  I notice that there haven't been any reports

recently of X1 crystal problems requiring refrigeration, or any

damaged TV's, so perhaps there have been some part substitutions

there too.

The last words out of user lostintime's mouth before he was banned

yesterday turned out to be quite prophetic:

   "I find it unacceptable that the Raspberry Pi Foundation has yet to formally acknowledge that the Raspberry Pi has any problems whatsoever, meaning it's quite easy for people to purchase a Pi while being completely oblivious to the fact that it has a known issue in a critical area which will affect the majority of its users in some way and which may never be fixed. It will be interesting to see what changes are made to the Raspberry Pi's hardware in the future and how they are justified by the Foundation when this situation is considered."

Ohh my, that is the solution they came up with ? ... at least I replaced them by 500mA fuses with lower resistance.

Oh well ...

-J

Well, well, how about that.  Just shows that we were on the right path with our recommendations all along.  Kudos to RPF when kudos are due:

• Message to Foundation #1:  Excellent move to finally recognize this error and eliminate it.
• Message to Foundation #2:  Very poor community relations to do this in total secrecy.

It's pretty funny, the extreme problem they have in being open with the community, even about those things that the community itself has recommended to them as design changes.  It's beyond bizarre.

Let's hope that they continue eliminating the other errors and misfeatures as well in future revisions.  This sets a very good precedent for their willingness to revise the design.

Alas it's sure to be in total secrecy again.  This sets a very bad precedent for their willingness to be open.

Morgaine.

Just in case this was an indication that RPF is interested in (and will act upon) suggestions for small incremental changes that can be done one at a time 1) to the BOM, 2) then to the layout, and 3) finally to the design, would anyone like to volunteer suggestions organized in that way, as small baby steps?

Borrowing liberally from everything that people have discussed here, an obvious trio could be:

1. Increase USB reservoir caps to reduce reboots on plugging in power-hungry devices.
2. Unlink the incorrect connection between 1.8V LDOs (certain to be in the plan already).
3. Feed the two host USB +5V lines from the other end of F3 to reduce +5V0 rail voltage deregulation by USB current fluctuations.

Morgaine.

You forgot one ...

  4. PR and Communty Relations

BTW IMHO the power design needs to be redone from scratch, including how power is delivered to USB devices. They can take a closer look at the Beagle Bone and Pand boards for a reference.

-J

Aye, I agree regarding overall power design.  Sadly that would be a rather XXL-size baby step, but yes, it does need to be redone.

I'm not really sure I should be in such a hopeful mood as I am, but good things seem to be so rare from that quarter that it really brightened my day to see that small revision.

I agree it is not a small change, but it would be a shame because I still consider the R-Pi a great idea and something worth to have, both for education and for people interested to thinker with embedded Linux.

To reduce costs I'd get rid of the FPC connectors and put together a board layout that is more case/mount friendly with mounting holes, a decent power jack, etc.

Also I'd add more GPIOs and interaces coming out of the SoC.

But the best thing that could ever happen is if they are willing to open the re-design process to the rest of the community and among other things release the schematics before going to production.

-J

Peg Wagner wrote:

 

by liz » 25 Aug 2012 10:37

And I'm impressed someone noticed so quickly!

 

From Me Peg: ... is it just me or does this seem kind of sneaky?

In the F1/F2 case, perhaps RasPeople didn't announce the change because they didn't want 10,000 cranky customers complaining that they want the Ohmless version, adding to distributors' confusion.

So for their next trick, perhaps RasPeople will modify the 1V8 connection to separate out the LAN9512 and its caps -- and they won't tell anyone about that one either.  The 1V8 change will be really hard to notice. 

@jamodio: I agree totally about those connectors --- a long time ago I made a case for

"Raspberry Pi Model "C" without DSI and CSI?" --- http://www.element14.com/community/thread/18357?tstart=270

Adding those two connectors as standard on a board that sought minimum cost was a severe design misjudgment, and it actually points to ulterior motives.  The plain goal of "lowest cost for engineering education"  simply does not justify them being there at all, particularly when it resulted in a reduction in GPIOs and hence reduced education utility.

I also agree with all of your other points.  A board for education should of course be totally open and their processes and design considerations should be shared with the community as well, and forum discussions about problems should be embraced openly and warmly of course.  Alas, given their utter hatred of openess, I fear there will be no change on this front.

@John:  Proclaiming that feature X has been accepted for addition to a future board revision does not require a date to be attatched to the announcement.  Dates would probably result in ordering slowdowns, so are not a good idea.  And dates would take us back to the silliness of the waiting game that was so annoying before.

Re the 1.8V change, aye, that's a cert.

Morgaine.