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

It would help to have a nice set of Gerber files with the current pcb layout to take a look a the traces and vias to chose what is the best course of action

before cutting stuff.

One option could be to just lift the two VDD18CORE pins, put togeher a small board that can be placed on top where the logo is with the 3.3 and 1.8

swtiched regulators, there are some very efficient and small ones like the LMZ10501 that can handle up to 1A and includes the FET and inductor

on the chip, add the decoupling caps for VDD18CORE on this board and run a wire to those pins. With some work you could manage to have

through hole pads to match the pads for the existing regulators.

I think there are two or three tiny ceramic caps that will get hidden under the add-on board. It may work ...

My .02

-J

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.

I really don't know how much effort to put on modifying the existing boards, what should happen is the RPF people acknowledge the problem, come up with a workaround, fix it for future boards and analyze the long term effects of THEIR ERROR.

Don't think anybody will be open to a massive recall, but the right thing to do is TO FIX THE ERROR.

My .02

-J

For $38 I don't expect a great deal of support, but I do expect that for a first revision board shipped naked without accessories or a case in limited numbers that it was never intended for the classroom in this form. More likely their target was developers and hackers to help mature the product, find bugs and develop software. I would hope that there will be future revisions, debugged, upgraded, shipped with a case and basic accessories, but I'm happy to tinker about with what I have; that is, after all, what I bought it for.

Well they missed the target for about couple of million miles. At the development phase price is irrelevant, and on the production phase what matters is cost, and not just components and assembly, you have to factor in that you will also need people and systems if you pretend to do a professional and serious job.

Being a charity or non-profit doesn't mean you have to cry all the time about it, I'm associated with non-profits that deal with huge piles of money and have a full time staff to do the organization's job to deliver on their mission and goals.

I think the argument "you get what you paid for" is very lame, I really don't care much about how much I paid for it or even if I had to pay much more to be part of what was promised to be an initiative to improve education on computer science.

There are no clear indications that there will be future versions or revisions and trying to obtain any information on that front is almost impossible. The only thing they keep talking about is the model "A" which is the same thing less few components and the camera module.

Still is a nice gadget to play with eLinux.

-J

jamodio wrote:

 

the right thing to do is TO FIX THE ERROR.

My guess is that fixing the error(s) is ongoing right now, and that this is why Pete has returned to the job.

There's total silence from RPF about it only because they can't yet figure out how to spin this into "Our perfect and faultless design is now even more perfect and faultless!".  But I'm sure that Liz will find a way.

jamodio wrote:

 

There are no clear indications that there will be future versions or revisions and trying to obtain any information on that front is almost impossible. The only thing they keep talking about is the model "A" which is the same thing less few components and the camera module.

Ironically, the Model A fixes the 1.8V regulator problem by not populating the LAN9512 , which also allows RasPi to run in a closed plastic case w/o heat problems.  Moderators at the RasPi Forum like to point out that the BCM2835 is used in cell phones without heat problems.  I don't recommend asking them how many cell phones have LAN9512 chips.

It was a good sign that Pete briefly showed up around here and somehow noticed and acknowledged that there are problems, but I'm not quite sure how much leverage he has.

On the thread he showed up and mentioned "the list," I asked about "what else is on the list?" and the only thing I got so far is white noise.

I already gave up trying to understand or figure what is going on with RPF, got tired of the default reaction and answer that "if there is something wrong with the Rpi the problem is YOU".

-J

John Beetem wrote:

 

Moderators at the RasPi Forum like to point out that the BCM2835 is used in cell phones without heat problems.

The moderators live in a fanboi partition of reality where facts are an inconvenient irrelevance.  The BCM2835 is not known to have been used in anything other than Roku 2 until the Pi, and no BCM28xx series VideoCore has ever been used in a cellphone.

It's the same odd partition of reality in which the Pi is called a "low power consumption" computer, the same "low power" that caused plastic components in that balloon payload to melt, and the same "low power" that doesn't allow me to keep my finger on the LAN9512 for longer than reflex time.

Pity that XKCD isn't too interested in us.  There's enough material here for volumes.

Morgaine.

Troy,

You wrote:

"More likely their target was developers and hackers to help mature the product, find bugs and develop software."

I think that is a widely held misconception.  Liz has explicitly said the

product is not in beta test.  Eben has explicitly said it is for sale to

anyone, not just developers and hackers.  If they were wanting to

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

bug tracking system, and they would be eager to hear complaints. 

Instead they ban people who complain, labelling them "concern trolls". 

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.

JamesH has made clear that they have no intention of disclosing

defects to potential buyers, and Abishur banned the guy yesterday

who advocated disclosing the known USB problems, and who said

he wouldn't have bought his RPi had he known.  Certainly they don't

show even the slightest bit of sympathy for those who end up

feeling duped.

So my impression is that their target market is the unsuspecting

buyer who is blinded by the low price.  I think they are afraid that

their sales would dry up if they disclosed that the product isn't finished,

and they seem to think that they can't afford to lose the sales to those

who end up feeling duped.

Troy,

You wrote:

"More likely their target was developers and hackers to help mature the product, find bugs and develop software."

I think that is a widely held misconception.  Liz has explicitly said the

product is not in beta test.  Eben has explicitly said it is for sale to

anyone, not just developers and hackers.  If they were wanting to

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

bug tracking system, and they would be eager to hear complaints. 

Instead they ban people who complain, labelling them "concern trolls". 

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.

JamesH has made clear that they have no intention of disclosing

defects to potential buyers, and Abishur banned the guy yesterday

who advocated disclosing the known USB problems, and who said

he wouldn't have bought his RPi had he known.  Certainly they don't

show even the slightest bit of sympathy for those who end up

feeling duped.

So my impression is that their target market is the unsuspecting

buyer who is blinded by the low price.  I think they are afraid that

their sales would dry up if they disclosed that the product isn't finished,

and they seem to think that they can't afford to lose the sales to those

who end up feeling duped.

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.

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

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.