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

. I'd love one of those IR cameras though... They'd be a bit harder to find in someones junk bin.

Definately... I even went and looked at prices for a new one

I think the argument "you get what you paid for" is very lame,

Possibly true.  My take on it is that something that's agressively designed down to a very low cost inevitably leads to compromises, doesn't matter if it's the RPF or IBM.  You have to account for that somehow and expecting the same results as something designed to a 10x greater cost with a huge R&D budget behind it just isn't realistic.

We may not like all the compromises, but it's done now. Hopefully a potential version 2 can improve things.

"Our perfect and faultless design is now even more perfect and faultless!".

That particular aspect of the mantra is one that really annoys me. Especially when Pete comes here with the 'flaws and fixups' thread and seems quite open that there are issues he's looking at.

If they were wanting to

find bugs and mature the product, they would have a highly visible

bug tracking system,

Yeah, it's long past the point where the blog and forum format outlived it's usefulness - I'd argue mid April when the first boards were delivered was when it should have changed. The Raspbian site makes them look so much better and they probably have less people and resources, so it's not hard.

Jamodio ought to be a hero on the RPi forum for finding what is probably

the most serious design error. 

Agreed. I haven't looked recently, but I noticed that they basically just blanked him when he posted it which, to me, says a lot.

Troy Mackay wrote:

 

Tooms wrote:

 

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

The microsope is really handy (and didn't cost me a cent), you'd be surprised what you can do when you can see what it is you are doing. I haven't even done a lot of SMD work. I'd love one of those IR cameras though... They'd be a bit harder to find in someones junk bin.

Hi

yes i am only having an magnifying lamp the glass ones with 40 leds and it is not very good so i have been missing this for an long time..

I ask my local hacker space if they hade an good microscope but they only got an older fix one, have not seen it.. so i have now my own microscope on the way and hope it will be here in 7 days time and then i can try do the hack you have done..

I can see you only have split the VDD1V8CORE but what about the other VDD1V8ETH and VDD1V8USB ?

Tooms

Hi

If it has a different signal name it is not connected to the 1V8 plane.  Like most good CAD systems it does 'mostly' what it's told.

I've been travelling again and not been able to get to my lab but I'm now in 'full' duplex conversation with Microchip (ex:SMSC).

I see the issue with 'higher' temp but now I get the feeling you are looking to fix something else with this mod?  Can you confirm?  There is mention of the USB issue - point me at it please and anything else you think is connected.

Cheers

Pete

coder27 wrote:

 

Jamodio ought to be a hero on the RPi forum for finding what is probably

the most serious design error.  Instead, he is banned as a concern troll.

I don't think I have to be considered a hero, somebody else would have noticed and reported the error(s) if RPF had released the schematics and Gerbers before sending the boards to production.

There is another major issue with the quality of some of the components as I reported before. In particular the LDO voltage regulators that on the beta board were from NXP and now are from some Chinese knock off.

In my company we are moving away from buying some cheap components produced in China, it is well known in the electronics community that counterfeiting of components have been increasing substantially, like one of the more known cases being the Nichicon aluminium electrolytic blowing up on monitors and computer switching power supplies since the counterfeit part used a very low quality dialectic and the part does not meet the specs.

To tell the truth this is not a complex board in number of parts, signals, nets, and we engineers often make errors, that's why when we work professionally we have a review process before we commit to large scale production. In this case the process didn't exist or some people were not paying attention.

What really concerns me (after all I'AM a "concern troll") is that this type of situation serves as a learning experience so we don't repeat the same errors or wrong processes, but I doubt that if there is ever a new revision or version of this board, we'll have the opportunity to review it before the hype-pi 2.0 starts.

My .02

-J

In my company we are moving away from buying some cheap components produced in China, it is well known in the electronics community that counterfeiting of components have been increasing substantially, like one of the more known cases being the Nichicon aluminium electrolytic blowing up on monitors and computer switching power supplies since the counterfeit part used a very low quality dialectic and the part does not meet the specs.

I must have replaced thousands of those in PC's, but that particular problem seems to be solved - at least from what I see.

From the people I know who work for chinese manufacturers it certainly appears that a large part of going to china is to do with getting counterfeit parts - if not the whole device!

Part of the problem is quickly going to become - if it hasn't already - that your 'original' NXP LDO will have been made in the same factory, on the same equipment, and to the same design as the chinese one. Maybe both will use the NXP design, maybe the chinese one. As long as they're not totally flaky and outlast the warranty there's a part of me that thinks nobody will care - stuff dying sooner means you replace it sooner and someone makes another sale. The beancounters like that idea

Have we all seen this before ?

I have no idea if it's real or someone just did a mockup to illustrate a point, but certainly made me smile

jamodio wrote:

 

What really concerns me (after all I'AM a "concern troll") is that this type of situation serves as a learning experience so we don't repeat the same errors or wrong processes, but I doubt that if there is ever a new revision or version of this board, we'll have the opportunity to review it before the hype-pi 2.0 starts.

+1.

Feedback on issues is part of the engineering process.  That's alien to Liz's hype & fandom process.

PeteL wrote:

 

As always - comments welcome.

+1

I've been trying to quantify one particular area of faulty operation, RF mice on self-powered USB hubs .  With dozens of tested (device X hub) combinations, and all 8 of the data points for RF mice showing complete failure on Pi, it's a very black-and-white test bench for USB functionality.  I happen to have a hot-running LAN9512, so I may be able to provide relevant testing if the 1.8v issues are thought to couple to USB operation.

Morgaine.

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

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

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.

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.

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.

 

Selsinork,

  Thanks for the explanation.  It makes sense. 

Here I've assumed that at least since Intel's fdiv bug, hardware

guys have had the advantage over software guys because they

use mostly formal verification techniques where we rely mostly

on ad hoc testing.

  I couldn't figure out at first why it was difficult to verify that

all the components on the RPi board were properly connected

to power, which I assumed to be a pretty fundamental property

to be sure was verified, until I saw that power flow isn't

specified on the schematics.

  It makes one wonder what is meant by the claims that the RPi

design was carefully checked.  How can you check something

that isn't specified, especially when the datasheets for the ICs

are either non-existent or ambiguous themselves?

  As technology gets more complex, ambiguity has to be reduced

so checking can be increased, just to keep reliability from getting worse.

The engineering process after initial release is about identifying existing shortcomings and evaluating alternative solutions for future releases, and doing this iteratively for each new version or model.  It is not about pointing fingers at engineers (which is completely irrelevant and unhelpful), and it is not about those engineers reacting defensively when problems are identified.

Reacting defensively makes it hard to analyse technical problems because it personalizes them, and when the defensive reaction is as extreme as on the Foundation forums and leads to messengers being banned, the engineering process is completely stillborn.  We're free of the latter here, but please let's remain free of the former as well.

PeteL wrote:

 

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

Pi Model B is most definitely not an engineering success.  Engineering success is a fairly measureable quantity related to how much of the engineering involved was actually successful, ie. how much of the product works as expected.  (And "success failure" is not a term any engineer should ever utter.)

If any other computing device had been found to have such a catalogue of compatibility problems when used with totally class-compliant USB devices, it is highly likely that it would have been recalled immediately and withdrawn from sales pending redesign.  The Pi is setting an example of USB incompatibility such as has not been seen since the first year of release of the USB spec and initial devices.

These USB problems appear to be in part fallout from least-cost BCM2835 SoC design and its USB  driver, and in part a consequence of excessively restrictive power design, but the board is a unit and its USB functionality is an extremely important part of its operation.  That key functionality has major faults.  It is not an engineering success (the only kind that concerns us here), because it is failing to operate as expected, and there are countless examples of how it is failing spread across the planet and reported on both RPF and Element 14 forums.

I'm going to assume that the objectively incontrovertible fact of widespread failures is accepted, because anything else would not be a professional engineering response given the evidence.  The big task then becomes to identify the reasons and find solutions, and that is why we are here, in my opinion.

Unless we can get past acceptance of the problems though, there is little prospect of finding solutions.

Regarding how the 1.8V design might affect LAN9512 operation, I have no evidence that they are related either, but I am just hoping that they are related in some way that we cannot currently see because otherwise it seems likely that the Pi's huge USB faults are with us to stay.

Morgaine.

Pete anything you are able and wish to share will be very valuable, I can say that so far I've not seen anything being shared yet...

I don't feel qualified to state if the mission of RPF has been or will be a success or not, my comment was referred to situations where people say "we tried hard," "we did our best."

Nobody will deny to acknowledge and appreciate the efforts but what it counts at the end are results.

At one time I had over 100 engineers working in my team and I never accepted that something that was accomplished by "doing their best" couldn't be done better and more efficiently, because as others said engineering is a cumulative process where we constantly learn and apply the new knowledge to do things better, and more efficient, and which will never be perfect.

I'm not a fanboi or a detractor of the R-pi, I still consider that it was a great idea and something worth to create, I'm not angry and I'm still using the 2 boards I purchased and planning to still work on some projects with them, now would I recommend it to local schools?, the answer at this time is NO.

BTW kudos to the UK and London for putting such a great 2012 Olympics.

Regards

Jorge