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

John Beetem wrote:

 

developing the wisdom

Not a chance, if you're referring to humans.  It hasn't happened over the few millennia of what we recognize as "civilization", and there's no sign of any change whatsoever now.

It's only our technological capability that progresses, not Homo sapiens itself --- natural evolution is simply not fast enough.  The only way the leading species on the planet will "develop the wisdom" is by integrating with our machinery and in due course leaving Homo Sapiens and its self-destructive grey matter behind.

That possibility is pure speculation, alas.  There is no guarantee that our mental activity can be integrated with machinery even with full control of everything down to atomic level, so the future may unfortunately be either/or, rather than a slow evolution from our unwise past into a logical future.

Morgaine.

There's a report today of a guy who thinks there is a correlation

between hot chips and ethernet cutting out and keyboard repeats.

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=24&t=14478

"Mine gets pretty hot. Heat I don't mind, but when it does get hot,

the ethernet cuts out and the keyboard repeats happen more often."

I see that mahjongg has become an apologist now, and doesn't even realize when he's teaching Grandma to suck eggs.  Sad.  I guess the fanboi disease over there is contagious.

The Foundation has already found the reason for dropped USB events.  No further speculation is needed.

Thomas Johansen wrote:

 

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

hmmm replying on my own posts..

But i am getting (i hope ) an microscope to the coming weeking and then i will try to do the hack Troy mackay and then do some more testing to see if this fix the heat of the LAN9512 and to see how low the power the RPI can run from as i like to do an project where it is running from an battery so if i can save 30-40% in power use by do this hack and replace the LDO then it will be good.

Just hope they soon will make an fixed rev. of the board so i can buy more boards with out this error.

Tooms

I now find it amazing and enterteining to see that the minions resist to accept that there are problems with the R-pi. "Hey there is nothing wrong with the board, you already tested 12 keyboards, why not 13 ?" and why a kid should carry the R-pi on their backpack ? Some of us minions of the RPF carry it on our underware !!

Sigh ....

Meanwhile I see "no list" or any other info being "shared," and it surprises me that there is not a single bit of information on the main blog site.

As the issues become exponential it will start to backfire, I'd stop production and selling until the issues get fixed.

Meanwhile APC is making progress announcing Newegg.com as distributor for US and Canada.

-J

jamodio wrote:

 

Meanwhile I see "no list" or any other info being "shared," and it surprises me that there is not a single bit of information on the main blog site.

That's what the guy Sulge who got banned at the start of the "USB discussions getting a bit heated" thread said.

He got banned for only a week (perhaps a sign that some admins are starting to realized that the emperor has no clothes), so let's see what he says when he comes back and points out that the very problems he was describing were confirmed by the Foundation's engineers.

Meanwhile APC is making progress announcing Newegg.com as distributor for US and Canada.

Excellent, that makes it a lot more likely that a UK distributor will appear before long.  The APC and BeagleBone are the only two cheap boards with Ethernet MAC directly on the SoC instead of attached over USB, so I'm very favourably predisposed to it.

certainly there have been plenty of opportunities on the

RPi forum and twitter for someone to say yes we have a

design error and it is causing chip temperatures to get hotter

than they are supposed to.

On the recent "case with fan" thread:

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=63&t=14323

bredman replies:

"1. The chips in the RPi are supposed to run hot, they are designed to operate safely to 120 degrees C."

On twitter, a similar question about fans is asked:

https://twitter.com/scottfrye/status/234232917583343616

Liz's reponse is:

"we're making good progress on the heat issue that some of

you are experiencing, with expert help from the other forum."

Oh wait, that's not quite what she said.  Instead she said:

"Why do you need a fan?"

Ron K Jeffries further clarifies: "It runs very cool, even when

overclocked to 900MHz.  Unless you live in the Mojave desert,

you'll not need a fan."

I think you said it best some months ago, that facts and honesty "interfere with her right to a new kitchen".

coder27 wrote:

 

There's a report today of a guy who thinks there is a correlation

between hot chips and ethernet cutting out and keyboard repeats.

 

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=24&t=14478

 

"Mine gets pretty hot. Heat I don't mind, but when it does get hot,

the ethernet cuts out and the keyboard repeats happen more often."

Here's my latest hypothesis.  We're seeing three outcomes of the regulatory battle between RG1 (1.8V regulator) and IC3 (LAN9512).

1.  RG1 has substantially higher Vreg than IC3 and thus provides essentially all the current for 1V8.  IC3's regulator switches off and IC3 runs nice and cool.

2.  IC3 has substantially higher Vreg than RG1 and thus provides essentially all the current for 1V8.  IC3 get very hot, but still functions OK, at least for now.

3.  RG1 and IC3 have almost identical Vreg and the regulation is unstable, with the current alternately being sourced by RG1, IC3, or both, depending on RG1 and IC3 temperatures.

(3) is probably quite uncommon since it requires almost idential Vregs, but if it does occur might add enough ripple to 1V8 to cause USB and Ethernet failures.  It would be interesting to put a 'scope on 1V8 near IC3 to see what it looks like on boards with USB/Ethernet problems not otherwise explained.  It shouldn't affect IC3's PLL since the PLL has its own regulator and its own 1.8V filtering, but if IC3 is rapidly warming and cooling you might get some PLL instability.

It's also possible that (2) is causing local heating inside IC3 that's slowing a critical path enough to cause USB/Enet failure.  If path delay is right at the edge, process variation or case design could make the difference.

Good summary.  It's worth pointing out also that voltage is only one electrical parameter here.  If any instability is present, the added inductance from the incorrect connection could also be relevant given that the LAN9512 expects nothing but decoupling caps on these tracks.

The 1V8 LDO powers PLL circuitry in the LAN9512, so stability is important.  Those 3 caps won't be decoupling the LAN9512 as effectively if they're simultaneously part of a larger on-board 1.8V mesh, even if that mesh is not misbehaving electronically.

Good summary.  It's worth pointing out also that voltage is only one electrical parameter here.  If any instability is present, the added inductance from the incorrect connection could also be relevant given that the LAN9512 expects nothing but decoupling caps on these tracks.

The 1V8 LDO powers PLL circuitry in the LAN9512, so stability is important.  Those 3 caps won't be decoupling the LAN9512 as effectively if they're simultaneously part of a larger on-board 1.8V mesh, even if that mesh is not misbehaving electronically.

Morgaine Dinova wrote:

 

Good summary.  It's worth pointing out also that voltage is only one electrical parameter here.  If any instability is present, the added inductance from the incorrect connection could also be relevant given that the LAN9512 expects nothing but decoupling caps on these tracks.  The 1V8 LDO powers PLL circuitry in the LAN9512, so stability is important.

According to the LAN9512 data sheet (Figure 2.2 -- Power Connections), the PLL has its own +3.3V to +1.8V regulator.  It appears to be wired up correctly in the RasPi schematics.

I wasn't so sure about their complete independence inside the LAN9512 when looking at the datasheet.

The VDD18ETHPLL and VDD18USBPLL lines are also connected to L3 which is specc'd at 100MHz so it seems strongly related to dynamic PLL operation (L3 is isolating ETH and USB sections from each other for RF, similar to L4 on the 3V3 side), and neither of those PLL lines has a tank cap like the 4.7uF on the 1V8CORE lines, so it doesn't seem to be caring about low-frequency stability.  That suggested to me that the PLL's 1.8V may actually be affected by the core 1V8 LDO, if not directly as a source (which seems unlikely since it's fed from 3V3) then at least indirectly through core logic.

When SMSC go to all the trouble of inductively isolating the USB and ETH sections of both their 3V3 and 1V8 LDOs, it's easy to imagine that they're not too impressed when their 1V8CORE pins are coupled to something foreign.

There are also some additional bits of information to consider based on reports of problems with Ethernet and the X1 crystal. If there are indeed power issues on the SMSC core that may produce unstable operation of the internal clock signals and ethernet is particularly picky about clock jitter and shape which may get the part to operate out of the IEEE specs. I've seen this problem with some Ethernet controllers/PHYs where temperature produces too much drift on the crystal/oscillator and the ethernet link is lost.

And who said that the parts on the R-pi are rated to operate at 120C ?

The PoP RAM chip on top of the SoC is rated for Commercial temp ranges, it varies from mobile to normal applications but it does not exceed 95C.

There is a lot of clueless folks at the R-Pi forum contributing wrong information to the already existing confusion.

-J

There's a dedicated thread now in the other forum.

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=29&t=14489

Love the classical cryptyc response from RPF minions ...

-J

coder27 wrote:

 

There's a dedicated thread now in the other forum.

 

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=29&t=14489

From that thread:

JamesH wrote, on the RPF forum:

 

Cannot say much about this, except that the Foundation are aware

of the problem and are working to rectify it.

And why exactly can the Foundation not say much about it?

This is a board intended for technical education, not a secret product hiding trade secrets for commercial advantage.  Why are essential items of information like the gerbers hidden?  Why are problems hidden?  Why are solutions hidden?  Why are future plans hidden?

I think I can summarize the questions more succinctly, if less politely:

Why is the Foundation full of it?

Morgaine.

There is a lot of clueless folks at the R-Pi forum contributing wrong information to the already existing confusion.

+1

Fairly clear that a lot of them are consumer level and are just blundering around in the dark..  If you dare to comment on them being clueless you just get shot down. Not worth the effort anymore IMHO.

selsinork wrote:

 

Fairly clear that a lot of them are consumer level and are just blundering around in the dark..  If you dare to comment on them being clueless you just get shot down. Not worth the effort anymore IMHO.

That's a comment that applies far more widely than just to RPF's non-technical followers.  Unfortunately humanity is largely broken, the far greater proportion of it not being able nor willing to be rational.  Spok would weep in sympathy.

It's instinctive for engineers to want to fix things, so when we see broken people, we occasionally try to convince them of their errors through clear factual and logical argument, but more often than not that's a doomed exercise since they "lack the hooks" for it to work.  More likely to succeed is appealing to emotion or self-interest, but those are not engineering methods and do not taste good to the engineering palate.  Also, most of us are not good at them.

I think it boils down to "Choose your fights wisely".  We can't fix the clueless millions, but we can focus on RPF as a public entity which is legally accountable for what it does, and we can focus on product which does have to conform to standards when claimed and does have to operate as advertised.  Those things do provide us with hooks so we're not totally powerless to fix what is wrong.

But no, we can't fix the clueless followers.  At best, only their descendents might be fixable through education.

Morgaine.

I usually read these posts with interest to keep abreast of discoveries of potential issues with the R-Pi but these last few posts have bugged me because they are as disappointing to read as the gushing exultations of fanbois.

The problem with contradicting peoples' beliefs and emotions (which is one outcome of hype) is that, in general, "rationality" of the Spock-kind comes over as being pompous self-righteousness, no matter how correct someone may be (with some egos confusing "usually correct" with "infallibly correct").

Convincing people relies on an aspect of humanity which most technical types I've dealt with seem to lack and that aspect is empathy

This means having to sit with the non-tehnical person in their viewpoint of the situation (because there was a time when you weren't an expert either), then guide them on a short-ish journey of self-discovery.

In my own job (Industrial Instrument Maker/Repairer) if you had no such empathy, you would continue to be called to jobs which the 'technically unaware' had 'fixed' themselves... like the truckie who would get a $10k tanker-decanting control system to work by bashing it with a rock, but I digress...

In addition, regardless of how well you make an argument technically, if the points you raise do not affect the majority of people in the pursuit of whatever endeavours they choose with the device, then you'll only be arguing for the sake of hearing your own voice and having nothing better to do.

Let's say that as a result of this endeavour to bring down the ruthless RPF Oppressor that there is some degree of success and the RPF folds as a result of it?

Would you be satisfied knowing that you've been proven technically correct whilst successfully preventing the device from reaching those people whom the device may work within their requirements or that the device now costs $70.00 before adding the power supply, etc?

How can you hope to educate the technically-unwashed when your war has made a casualty of the only potential path they have to understanding in the near future and you've offered no tangible and immediately available alternative for equivalent cost?

I'd like to see less posts of the "For the glorious struggle against the oppressors of freedom that are the RPF" type and more of the "These are my findings and in day-to-day operations of type x under conditions y, then the device may fail", the likelihood of this happening (MTBF) and also  what the wider effect this has, bearing in mind that the investigations presented thus far cannot be demonstrated as being representative of a large sample of all devices produced.

If you want rational, be wary that you don't become irrational in your efforts to secure it.

Also remember that there's a difference between fit-for-purpose and a technically-perfect design, and that these states are mutually exclusive in the minds of most techie types, if the former exists at all.

Would you be satisfied knowing that you've been proven technically correct whilst successfully preventing the device from reaching those people whom the device may work within their requirements or that the device now costs $70.00 before adding the power supply, etc?

There is no war and these are not issues related to "people's requirements," there are design errors and basic stuff that does not work as expected, and unless the requirements include blowing up TV's, collecting power supplies, USB hubs, keyboard, mouses and SD cards, like it or not the R-Pi has design and functional problems that need to be corrected so the people that are the main target for this device can receive what they expect.

About the cost, RPF continues to provide a bogus and misleading statement on their home page ...

-J