RG1 1.8v regulator

As shown in Troy Mackay's post on Jul 28 it seems to me that we could mod our PI's to work more as the chips were designed.

I think that this could make the PI more stable, from the looks of it.

I am not a designer Just an old tech, but I think we need to find a way to FIX what we now know is an error in the board.

So could someone do some practical testing to see if there is something that can be done to easly fix the current board, rather than wait for RPI foundation to fix it by waiting for a board redesign?

i will love to try out the hack Troy mackay has done also and then test again with that fix on the board, but i have looked into this and i most say it is very well done by Troy as i think it is to small for me todo and i done have an microscope as need for this.

so yes if some one can findout where to make an cut to split the LAN9512 1v8 from the lod 1v8 then i will try this also.

Tooms

J

Connecting the two 1V8’s is a sub optimal piece of design (you can look that up in the engineering translation dictionary - starts with a 'c' ends in ‘up’), and I didn't think that was of debate.

The design did go through extensive review within the 'inner circle' of supporters who 'know' and have worked with the chips before especially the BCM. Both prototypes and pre-prototypes had this same connection and that of course made it more difficult. I also suspect, had there not been some reason to go and look, it would have never been identified. Just for the record, your technical input is appreciated, but rather than just implying - you could have just asked? Maybe you did earlier and I missed it.

We tried to do the best job possible with the limited support and resources that the early phase project had. (We were going to make 5000-10,000 beta boards max). None of the early stress testing revealed the issue and only a small population (sub 0.01%) are reported to run unbearably hot (although more may, just not flagged up because it does not concern their owner - they are just having fun with it). Of the returns I have for analysis, I have still have not found a real ‘steamer’. These could be in part due to poor underfill or even a short/defect elsewhere on top of what we are asking the chip to do.

There is an implication in posts that this is responsible for something else to do with USB but to date no info is forthcoming? (Stop press - just seen that other thread - will go and look later).

It doesn't matter if you spend £1 or $10M things slip through, and there have been some very high profile events in that $10M category in all walks of engineering!

I remember saying at the outset that Pi would never be perfect - just doesn't happen in engineering there is always something to be optimised, improved. What we do need to do is measure, evaluate, garner input and decide what, if anything, needs to be done. And I do appreciate the work done by people on this thread already.

Pete

Question is - were the Rubycon's real !

P

Pete,

You wrote:

"There is an implication in posts that this is responsible for something else to do with USB but to date no info is forthcoming? (Stop press - just seen that other thread - will go and look later)."

I'm quite sure that there is no established connection at this point

between this 1.8v power issue and any USB or other functional problems.

Users with hot lan chips have been having USB problems, but so have

users with cooler lan chips, so the USB problems could very well be due to

other causes.

SMSC has said "don't do that", but they haven't said what will happen

if you do.  We've seen pretty convincing evidence that the lan chip

will get hot, but don't know if it will malfunction, or cause a malfunction

on the other devices connected to 1.8v, or whether its expected lifetime

will be shortened.

you wrote:

"only a small population (sub 0.01%) are reported to run unbearably hot (although more may, just not flagged up because it does not concern their owner - they are just having fun with it). "

I'm not sure what you are basing your statistics on.  Is it the return rate?

I suspect that the rate is higher than 0.01%.  If the rate was that low,

then certainly there would be no hesitation to announce that due to a

design defect, a very small number of boards have chips that run blisteringly

hot, and any user who is unlucky enough to have gotten one is welcome

to exchange it.

you wrote:

"We tried to do the best job possible with the limited support and resources that the early phase project had."

I don't think anyone would deny that you did a fantastic job with the limited

resources you had.  But I think jamodio's point is that releasing schematics

prior to production would not have cost anything, and could have resulted

in great savings by uncovering such errors before mass production.

I am not a hardware guy, but I am quite surprised to see that hardware

schematics aren't clear about the direction of power flow.  It is a bit

ironic that the beta board had a string of decoupling capacitors that

should have been connected to 1.8v, but wasn't, and the production

board has a similar string of decoupling capacitors that shouldn't have

been connected to 1.8v, but was.  But there is nothing in the schematics

to show which pins on the ICs have power going in, and which have

power coming out.  So it is very difficult to check the schematics to

find these kinds of errors, where components are either not connected

to any source of power, or are connected to more than one source.

At this point we are completely in the dark about what hardware revisions

are contemplated, other than Eben's mention of some unspecified pcb

change for FCC/CE residential compliance.  Hopefully that will change.

Eben said he wanted to fix the FCC/CE issue prior to the educational

release.  Since the 2012/2013 school year is about to start, the timing

seems really odd not to have fixed that by now.  The timing also seems

really odd not to have published the user's manual by now.  Amazon is

showing a projected date of 16 October.  So are you aiming for the

2013/2014 school year?  If so, I'm quite sure you will need 512MB ram

to be competitive.

First of all thanks for being here and for following up. I really appreciate the work you have done and I truly believe that some of the mishaps from the RPF are not your own making.

 

Connecting the two 1V8’s is a sub optimal piece of design (you can look that up in the engineering translation dictionary - starts with a 'c' ends in ‘up’), and I didn't think that was of debate.

Well, you may call it "sub optimal design" but it is actually an error, and in my dictionary it starts with 'f' and ends in 'up' ;-)

 

The design did go through extensive review within the 'inner circle' of supporters who 'know' and have worked with the chips before especially the BCM. Both prototypes and pre-prototypes had this same connection and that of course made it more difficult. I also suspect, had there not been some reason to go and look, it would have never been identified. Just for the record, your technical input is appreciated, but rather than just implying - you could have just asked? Maybe you did earlier and I missed it.

Obviously the process didn't work, and as you clearly know in the previous prototype it was reported that various power connections were missing, kind of a surprise since part of the 'inner circle' was apparently involved in the design of the BCM SoC chip. Perhaps the 'inner circle' has a very small radius and some of the supporters actually "don't know." Not just me but many other asked while before the boards went to production for schematics/gerbers and the only we obtained was a crop showing a psu section. I reported the problem as soon as the schematics were made public, and it didn't took too much know how, just reading the SMSC datasheet to figure what each pin was used for, something that we don't even have for the SoC part.

And about asking, I asked what else is on "the list", no response yet.

  We tried to do the best job possible with the limited support and resources that the early phase project had. (We were going to make 5000-10,000 beta boards max). None of the early stress testing revealed the issue and only a small population (sub 0.01%) are reported to run unbearably hot (although more may, just not flagged up because it does not concern their owner - they are just having fun with it). Of the returns I have for analysis, I have still have not found a real ‘steamer’. These could be in part due to poor underfill or even a short/defect elsewhere on top of what we are asking the chip to do.

The foundation should have put they arrogance away and ask for help and additional support, there has been a large group of people willing all the time to cooperate, and they are still out there but the RPF attitude has been always "what we did is perfect and we know everything." I'll not trust any number, percentages or analysis derived from them given that there are no public numbers about how many boards have been manufactured, how many have failed, how many have been sold. how many have been shipped, how many have been returned, etc, and there is no formal or reasonable system to track complains/failures/fixes.

There is an implication in posts that this is responsible for something else to do with USB but to date no info is forthcoming? (Stop press - just seen that other thread - will go and look later).

I'm not sure if there is a direct connection with several of the problems reported with USB. Certainly the entire power architecture does not help, but there are some hardware/firmware issues related to USB where things are not working as expected and somebody is now reading the Verilog files for that piece of silicon on the SoC discovering some limitations and other stuff hidden behind the obscurity of the drivers.

I know that everybody have tried to do their best, but recognition for a successful endeavour comes from producing positive results and not from the effort put to get them.

My .02

-J

So I guess it is not worth me publishing here what I know and what I can measure?

I do take issue with your final comment - it has been a success so far - with some measure of "success failure" thrown in.

I've been talking to users who just have one or two and are over the moon with them (faults issues and all) and they tell me that they have already learnt so much.

My overall positive view may yet be proved wrong, but as I said right at the outset it isn’t perfect, never will be - we just have to remember why we are clearing the swamp!

Off to watch the Olympics on TV

Pete

I am not a hardware guy, but I am quite surprised to see that hardware

schematics aren't clear about the direction of power flow.

In many years of working in the subcontract hardware assembly business I've seen hundreds of schematics from all sorts of companies, from the biggest names to tiny one man outfits and I've rarely seen anything indicating power direction.

This sort of thing wouldn't have been a problem in years gone by as it was rare for IC's to have internal regulators and often power was supplied from an off board supply so it was obvious.

Things change, technology gets more complex, leaving room for ambiguity and errors to creep in.

IME Petes schematics are pretty good, they lack some things you'd normally find on much larger schematics like a cross reference of refdes and signals to page and location, but for four pages most of that stuff isn't really necessary.

lol.. nope.. it's like one of those russian dolls you keep removing another layer until you get to the 0201 smt cap somewhere inside

So I guess it is not worth me publishing here what I know and what I can measure?

I'd certainly appreciate anything you're willing to share Pete

PeteL wrote:

 

 

 

I remember saying at the outset that Pi would never be perfect - just doesn't happen in engineering there is always something to be optimised, improved.

There is a story about a craftsman who made beaten copper doors for the Tsar of Russia's throne room.  He would take a large sheet of copper and beat it over and over with a hammer, creating beautiful swirling patterns.  Someone asked him "how do you know when you're done?"  He answered: "It's never done.  I just keep hitting it until they take it away from me."

Engineering is like that -- especially software engineering.

Thank you for being open to suggestions, Pete!

Pete,

>So I guess it is not worth me publishing here what I know and what I can measure?

You are being way too defensive.  Nobody is blaming you for the design error.

If I understand your earlier comment correctly, the error was copied from the

alpha board that you didn't design yourself.  And I don't think it matters much

to hear that you have found a happy customer.  On this forum and the RPi

forum, happy customers are hugely outnumbered, not that that matters either.

It would be very nice for you to publish what you know and what you

can measure.  However, regardless of what further information you can

provide, I think it is clear enough at this point that the lan chip is not

supposed to be blisteringly hot, as people have been complaining about

in vain for months, and it is essential to promptly tell those customers what

their remedy is, rather than what they have been told so far, which is that

hot chips are normal in PCs.

Going forward it is clear enough that the foundation has limited resources

for debugging their hardware and software, and would greatly benefit from

a bit more openness with regard to schematics, and a bit more cooperation

with those who point out problems.

Pete,

>So I guess it is not worth me publishing here what I know and what I can measure?

You are being way too defensive.  Nobody is blaming you for the design error.

If I understand your earlier comment correctly, the error was copied from the

alpha board that you didn't design yourself.  And I don't think it matters much

to hear that you have found a happy customer.  On this forum and the RPi

forum, happy customers are hugely outnumbered, not that that matters either.

It would be very nice for you to publish what you know and what you

can measure.  However, regardless of what further information you can

provide, I think it is clear enough at this point that the lan chip is not

supposed to be blisteringly hot, as people have been complaining about

in vain for months, and it is essential to promptly tell those customers what

their remedy is, rather than what they have been told so far, which is that

hot chips are normal in PCs.

Going forward it is clear enough that the foundation has limited resources

for debugging their hardware and software, and would greatly benefit from

a bit more openness with regard to schematics, and a bit more cooperation

with those who point out problems.