Electrical Engineering

Anonymous

2:04 AM

I2C headache, if I i double the manufacturers claim for "maximum time before data" their sample code works, if I leave it be their sample code times out 50% of the time

@PatoSáinz There was a parade today and nobody was wearing this

Anonymous

@crasic Lesbian, Gay, Bisexual, Transgender and Engineers

crasic

May as well be, half of everything was sponsored by tech companies

Nick Alexeev

2:23 AM

@PatoSáinz It's a sign that means "it's complicated".

@crasic Which I2C device are you grappling with?

crasic

@NickAlexeev atmel sha

The code is - send command - wait minimum time - try reading - if nothing poll for ready until maximum time hit

but it times out - consistently, every other assy

Nick Alexeev

@crasic Does it hurt to increase the timeout time like 10x ?

... and call our neighbor Atmel on Monday.

crasic

They haven't been helpful

although I have bus captures of succesful and unsuccseful communications

it needs a wakeup command and they try to resync so it basically chokes on its own

Maybe with data I can get an engineer to talk to mne

@NickAlexeev I have to understand why and engineer a way to be resilient , this is a supposed to be for security lockout, if it might not work as expected and deletes our ip customers won't be happen

Ideally I would write comm code from scratch myself, at some point when there was too much to be done this device was pulled in from sample code and it has been living like that and misbehaving since

but infuriatingly inconsistently

Asmyldof

7:16 AM

@crasic Can't say that I have had any of those problems using it with Mega, Xmega, SAM or LPC. Though with LPC there were many other problems, but that's LPC :-D

And SAMs usually have something inside, so it doesn't happen often I use it with that, as well as XMegas. Those were mainly tests with experimenter boards.

PlasmaHH

9:07 AM

@jippie only with free access to the necessary power lines...

but at least it has these nice red carry handles...

Asmyldof

@PlasmaHH matter of some industrial grade metal cables and a grappling gun, isn't it?

PlasmaHH

@Asmyldof would need some space to run the cables thorugh...

Asmyldof

9:28 AM

Air?

PlasmaHH

@Asmyldof and held there by siemens airhooks?

Asmyldof

... what part of grappling gun did you not understand?

:-P

PlasmaHH

the part where it enables me to run a few km of cable freely through air? ^^

Asmyldof

Surely you are going to have some cables near?

PlasmaHH

@Asmyldof 380kv? that would be quite a few kilometers outside the city

Asmyldof

10:27 AM

Does it matter whether you get 230V or 18V?

It'll still be welding currents, so....

PlasmaHH

I can't draw more than 65kVA from anything thats within reach... pretty lame it would be

Asmyldof

65kVa over a 1mm gap.. let alone 0.1mm... that's serious plasma, plasma

Titanium arc welding, etc

Asmyldof

11:06 AM

@PlasmaHH Or, you could just have a blimp hold up the wires above your transformer... presto, done.

PlasmaHH

@Asmyldof hm, low on budget here, can I use a hydrogen one instead of helium?

Asmyldof

Sure! Can't see why not

I hear Germans did that before with great success, by the way

jippie

12:59 PM

@PlasmaHH The other day I was at the factory in Nijmegen where they make those transformers. Impressive beast if you stand next to one. Even a single coil is huge, not to mention the core material.

PlasmaHH

@jippie Hm, how big are the windings? Skin effect should be about 9mm at 50Hz so this might be getting an issue there... and what is the core material? surely not laminated steel or ferrite...

jippie

laminated steel.

windings are square copper, or at least flat so it stacks easier.

PlasmaHH

thats going to be a hell lot of layers

jippie

windings are wrapped in paper, best isolation for the job.

PlasmaHH

Just hope its not cheap newspaper ;)

jippie

1:06 PM

@PlasmaHH Royal Smit Transformers are one of the world's leading manufacturers, I don't think they use newspapers to wrap the copper.

PlasmaHH

@jippie thats good, I was just imagining the oil boiling and the thing exploding... it loosk nice on a small transformer, wonder how it looks like on those ^^

jippie

@PlasmaHH once a coil is wound, it is dried. By removing the moisture from the paper, the coil shrings about 10cm in height.

I'm really an electronics guy, but it is amazing to have a tour in a factory like this one.

you kinda feel very small ;o)

PlasmaHH

same for A380 assembly...

Asmyldof

1:28 PM

@PlasmaHH @jippie Technically, they could be using newspaper, with governament and market pressure on using receycled. Sure, it's not visible as newspaper any more, but, it's quite likely it is for 50%+

Do they use a single winding, or parallel sets for skinning and fringing? And in either case, about what size?

Facts man, facts!

Numbers.

With decimal points

:-D

PlasmaHH

@Asmyldof the problem with newspaper is the toner. It is mostly pure carbon and dissolves after a short time in the oil

Asmyldof

@PlasmaHH No, no no, you were talking about the news_paper_ not the news_toner_

:-P

Asmyldof

2:26 PM

@PlasmaHH liked your comment-answer to the HV cap question :-)

PlasmaHH

@Asmyldof I really never understood how people could ask questions at that level... It is like those "I want to learn electronics, what projects could I do" things

oh that next one is even bette

r

jippie

@Asmyldof They use six windings :-p

@PlasmaHH yeah they have this strange "worry" about arcing between windings, amongst other things because of contamination. Don't know why.

Asmyldof

@PlasmaHH Luckily someone added the option to vote "I'm voting this off topic, because it's blatantly off-topic" to the last one

Which I just clicked

PlasmaHH

it needs some rep to do

jippie

I believe one of the reasons for their worry is that after the transformer has exploded, similar sized transport is required to transport the bits and pieces back to the factory for post mortem analysis.

Asmyldof

2:36 PM

@jippie But whether that contamination comes from trees or newspaper, they'll have to stringently wash in all kinds of hydro-fluorides anyway, so I bet that they use waste paper as well to seem "clean on paper" (pun somewhat intended)

Lol

@PlasmaHH I know. I'm working on getting there ;-)

jippie

@Asmyldof not sure if you are LOL'ing about the transport thing, but that is actually a serious issue. You can't just send the thing back to the factory.

PlasmaHH

after it has arced...

Asmyldof

@jippie I know, but it is funny to state that as primary fact of worry rather than the socio-economic issues concerned with something you built or tested&verified exploding with an energy level associated with 380kV @ whatever those things are allowed to peak at in current.

Wasn't it in Russia one of the universities had a small transformer explosion costing them half a wing mid 2000's?

jippie

@Asmyldof hundreds of MVA's, can't recall.

Asmyldof

Believe it was only treatably woundeds, but still

That was one rated quite the same as the connection the TU/e has (or had, now EE had to move?)

jippie

2:43 PM

@Asmyldof another worry would probably be that it is bad for your company name in the transformer business ;o)

Asmyldof

Ah, you can always Peugot it and move into consumer business. start making laminated bicycle frames

jippie

wait I saw this little video from KEMA the other day, it was 11kV I believe

Asmyldof

We were always joking about "accidentally dropping a wrench over the railing"

Or once in a while "accidentally dropping one specific professor over the railing"

:-D

jippie

Kortsluiting onbeveiligde elektra kast

►

that one is tiny

and unavailable apparently :-/

PlasmaHH

?

I wonder what material went up in smoke there... likely not healthy

jippie

2:49 PM

just a Rittal'like cabinet I believe

DNV KEMA done some cool experiments in their labs :-p

PlasmaHH

yeah, if someone gave me a few thousand ultracaps I could do some cool experiments too...

jippie

DNV KEMA sylteagurk

►

@PlasmaHH they don't use caps.

PlasmaHH

sure, but for me it would be cheaper to use caps than to have some bigger power lines installed ^^

Asmyldof

@jippie Guess who was there when they did that cabinet explosion

I could quickly see mr Ypma at the end of the look around as well

I think

jippie

3:13 PM

@PlasmaHH they don't use power lines either.

PlasmaHH

overunity circuits?

or a bunch of cr2032?

jippie

@Asmyldof John McEwan?

@PlasmaHH damn it was supposed to be a secret.

Asmyldof

@jippie Well, it was either a very similar explosion to the one I witnessed together with some fat-cats and colleague recent ex-students and students, or it is the exact same, the back of the head and profile of one of the guys there reminds me of someone who was there. I just didn't see myself on the look-around, so it may be a coincidence. I know Edwin was filming with his digi-photo-cam and did a look around.

Nope, just saw all the way at the end who was laughing in suit, that's one of my predecessors at the student board, very likely the same explosion.

Asmyldof

4:09 PM

I feel like baking

What should I bake and why?

Winning suggestion MAY be eligible for a DHL World Express package with part/one-piece. No warrantees to freshness and or mould-free-ness.

Anonymous

4:20 PM

@Asmyldof

Anonymous

No-Bake Cheesecake Flag Cake -- 4th of July Flag Cake

►

Asmyldof

@PatoSáinz Nope. No-bake is not bake, disqualified. Also 4th of July &/| US themed suggestions will by definition not win

:-P

Anonymous

hahahaha it's tasty tho, I made it once

Asmyldof

Anything with strawberries is tasty, because strawberries are tasty, which is also why adding anything to them is a pointless exercise, which is why that's another reason the suggestion wouldn't have won :-P

Anonymous

@Asmyldof ibmchefwatson.com

Asmyldof

4:26 PM

Denied

Anonymous

why

Asmyldof

Because the suggestion to have me use a website to create a suggestion is a non-suggestion

And, also, mainly, because I don't do recipes. I do ingredients and targets and what comes in between is art

Anonymous

last try

Anonymous

Osama bin Laden Death Day Cookies!

►

Anonymous

is that good enough for you?

Asmyldof

4:28 PM

I like the Death-cookies part

crasic

Anybody know of a bus analyzer that works with precaptured data?

Asmyldof

Not so much a fan of the juxtaposition of them being OBL Death Day Cookies and they then needing hate

C/C++ and a compiler?

So, effectively, no

Oooh, or Python

crasic

Yeah that was my plan B

Asmyldof

Python+PyGraph+PyMath+PyAwesomesaucePlugin

crasic

I have the libraries written to load in the scope data and format it nicely, wanted to avoid banging out an I2C reader

PyI2CTranslator

Asmyldof

4:30 PM

Should be easy

crasic

The stupid thing is that my scope does the bus analysis for me, but refuses to save the translation

Asmyldof

Easy enough to do, if it were my problem. Which, luckily, it isn't, so I can safely continue thoughts about baking

Rigol bug?

crasic

2GB of trace data though

Asmyldof

<-- has 0 Rigols

crasic

No DPO

er tek DPO

Asmyldof

4:31 PM

Hm

Heyho

Eh

Is the data saved in a manner that's compatible with.

Eh

Crap, forgot the name

Free SW or maybe even Open Source hardware based PC USB Logic Analyser 24MHz

Saleae

Sal...

Something with Sal and too many sounds after it

Anonymous

saleae

Asmyldof

saleae.com/…

I were rightly!

Anonymous

@Asmyldof do you know what is the hardest part of building that little circuit for 2x the frequency?

Anonymous

scavenging the damn resistors

Asmyldof

?

I have a cheap fake Chinese one... Very happy with it for travel purposes

Anonymous

4:34 PM

I have the caps, the mosfets, the diodes

Asmyldof

Carrying big 32 channel machine with laminated iron core transformer = meh. Carrying tiny plastic box and laptop I needed anyway = yay

Anonymous

but I have a bag full of old pcbs with through-hole resistors

Anonymous

and it's just too much to start filtering through to get the values I need

Asmyldof

digikey.com mouser.com newark.com ?

0.01% value increments

Anonymous

@Asmyldof nope, here in Chileistan, getting electronics is a hassle and shipping is a hassle

Asmyldof

4:36 PM

or 0.1% if you don't want to spend more than a dollar per piece. 1% if not more than five cents. 5% if not more than a cent

Getting a gun though....

Gun --> cheap electronics

Anonymous

there are a couple of radioshack-esque stores BUT they all are progressively stopping selling components and now they sell arduinos and shields

Anonymous

@Asmyldof soldering gun I presume?

Asmyldof

No. Bullet gun

pewpew-type

Anonymous

soldering bullet gun

Anonymous

at the end of the day, bullets are made from lead, and so is solder

Asmyldof

4:40 PM

Yes, but bullets go faster than solder. Faster is better

Next time shoot your components, QED

Anonymous

speaking of damaging components: I'm tired of only having a 500W soldering gun

Anonymous

I need to get a soldering station with regulated irons and things

Asmyldof

500W?

Mount a blower above it, you'll have a hot air gun

Anonymous

somewhere in between 250 and 500

Anonymous

I do have a hot air gun haha

Anonymous

4:42 PM

750W

Anonymous

or something

Asmyldof

INstallation wire wrapped around a nine inch nail?

Anonymous

@Asmyldof not good enough thermal transfer

Anonymous

the best part is that the little transformer inside the gun heats itself too after a while

Asmyldof

Then why 250 to 500?

That's normal

Anonymous

4:43 PM

@Asmyldof because I can't quite remember the exact value

Anonymous

yea but it's overkill and not precise at all

Anonymous

so I end up heating up some components and I fear I may damage them

Anonymous

and dry some electrolytic caps

crasic

Weller WS-50 is a good replaceable tip station

Asmyldof

Which, as we all know, should be done with the use of a reflow oven stuck in pre-heat due to badly designed PID

crasic

4:45 PM

WES51D

I have a metcal and hakko and the tips are just amazing

Asmyldof

Or any of a number of stations that do not cost less than $50

crasic

Desoldering tweezers are a great addition

Asmyldof

I have about the entire weller 1970 - now range, skipping some redesigned models

because who needs glossy teal rectangular WTCP50 if you have three in-places-molten mint green MagnaStat-50 's

I like the new smart stations. Sounds like a lot of money for nothing until you start using them and then at some point look across to the WPS81 (I think?) and think towards it: You foolishly simple toy. Caveat: To a hobbyist they are most certainly going to be money wasted.

crasic

the wes51 is basically the magnastat with a temperature knob

Asmyldof

Except that with a temperature knob it's not the magnastat

crasic

4:51 PM

It has the locking mode with magnet pen

Asmyldof

Egh

That's...

Nope

Glad I skipped that one

You either have nubcakes you don't trust, and you don't give them a knob, or have one that can be locked, like in the 80/81 series, or you accept that you have proper engineers in your workplace and give them a freely movable knob

crasic

Its movable but you can lock the temp with a pen

Asmyldof

For children's workshops I prefer the Magnastat no-knob solution on account of kids break everything that is supposed to be lockable (proven fact!)

Then it's not magnastat

crasic

fair enough

Asmyldof

And too over-engineered for my taste

crasic

4:57 PM

its their mid range current model

Asmyldof

Nice $3.50 magnastat tips are great for kid's workshops

Anonymous

a propane torch works, too

Asmyldof

Nobody needs to know what's going on. No parents freak out about "Oh god, it's 300 degrees!"

Fckn parents

crasic

Its a black box that glues wires

no heat here twiddles thumbs

to be fair though, my parents got me my first soldering irons as a kid

Asmyldof

I have guided 6k+ children in soldering workshops to date.

1 blister

On me

I was allowed my dad's Weller when I was four.

Anonymous

4:59 PM

@crasic same

crasic

I've neer burned myself on an iron, but I have burned myself picking up desoldered parts

Anonymous

@Asmyldof is that volunteer work?

Asmyldof

But look at society now: If you send your kid to school with a long blister on his/her arm you get hit by the inquisistion

@PatoSáinz yup

Anonymous

@crasic I've only burned myself with a clothes iron and with my metal forge

Asmyldof

Well, yes and no

If the organisation pays all other activities $$$$, then I'm billing too, if it's partly volunteer but with sponsoring, sometimes I bill material cost, if it's mainly volunteer I bill naught or near-naught

Anonymous

5:01 PM

@Asmyldof and what kind of organisation is that organisation?

Asmyldof

4 to 6 I definitely went to school with blisters!

crasic

Sounds lovely

Asmyldof

Depends on what organisation wants me to do a workshop, dunnit?

Anonymous

@Asmyldof oh, i see

Asmyldof

If it's a First LEGO League regional that needs some schedule filling, or a HOT-Final or regional I'm libel to "forget to send the bill"

If it's a BeNeLux final of same, they're getting the full one, because the organising group pays themselves full time to let volunteers do the work and then show up at the end and go "Gee, look at what we made here, we are so fckn awesome, we should get a raise!"

But when someone (like me) bails out a year they get call after call from the person following them up, because they have no clue what needs to be arranged

And if a Dutch organisation for the promotion of technology needs me, they get the full bill too, because they pay every single person involved, so why not me?

And if a local community group has an activity day and they know about me and invite me I never even talk about cost, up to a certain amount of participants

etc etc

Anonymous

5:06 PM

alright

Asmyldof

Very dependant on who, what and where.

Anonymous

well, sushi time

Anonymous

bbl

Asmyldof

Yes plx

Anonymous

you should go bake something

Asmyldof

5:08 PM

After dinner is done

About which, bbl too :-)

crasic

6:54 PM

All of this work to realize that we are not waiting for I2C as long as we thought we are

PlasmaHH

Hm, it takes a considerable force to move the mouse... time to clean up the lab desk to make some room for it...

Asmyldof

7:50 PM

LOL

at both

@crasic Told you I never had problems with the Atmel SHA :-P

crasic

The benefit of this exercise is that I can now read I2C packets in my head off a data trace

Asmyldof

Do you go bip for 1 and boop for 0?

I do

When I see pulses on a line I go Bip Bip Boop Boop Bip Boop Boop Bip, ah that's 0xC9

crasic

8:06 PM

lol I'll try that

Any idea how many nacks the kernel listens for before returning NACK for read?

Asmyldof

Eh

crasic

because I'm 90% sure that it does 4 read attempts on the kernel side, before giving it back to us

Asmyldof

Depends on the kernel module

crasic

our read loop polling does bursts of 4 read attempts on the scope

which makes me thing the kernel is filling in the 4

Asmyldof

That is possible

crasic

8:08 PM

Ok, so not going crazy

have to find what exact i2c module we are using

Asmyldof

IF you are using a pre-created module that hosts an I2C device it may have a retry scheme

crasic

its some real time compatible i2c (generic) kernel driver

Asmyldof

And usually that's set to 3, 10 or 25 depending on the environment and exact bus

crasic

which I haven't looked at yet, and then higher level code from atmel does read attempts until the max execution time of a sha command

Asmyldof

But people sometimes make mistakes and don't count your forced try, so 4, 11 and 26 would also make sense :-)

crasic

8:09 PM

which is anywhere from 4 to 40 ms

o.O

ok gotcha, thanks for the info

Asmyldof

No worries

crasic

Atmels code assumes a certain execution time for the read command, I think our driver is polling longer = not waiting long enough = timin out

Asmyldof

I think RPi default module did 3 or 5

But...

crasic

so screw this and I will use real system time to check the read polling

or rather polling shorter

Asmyldof

Isn't there a call back?

crasic

8:12 PM

Its all done in a busy loop

Asmyldof

I know Atmel doesn't always use the.... best route from a RT perspective in their examples

crasic

its more that they assume and define a time for the return of a single read

and then use this to keep track of the number of ms since polling started

Asmyldof

Hm

I like writing call-backs for things like that

crasic

yes, same, ideally I would rewrite this

but step 1 was figuring out why it isn't working

using the existing code

Asmyldof

I find it hilarious that ASF (Atmel Software Framework) is modded for ATSAM procs, but uses 0 DMA controllers

crasic

8:14 PM

ironically, the definition is so perfectly fit, that we are on the razor edge of timing out

sometimes 16 polls, sometimes 17, we time out at 16

Asmyldof

hm

crasic

actualyl waiting until the full "max execution time" in the sha datasheet makes everything work well.

and you can see on the scope where there is some preemption going on

Asmyldof

which number do you use?

crasic

the clock halts high/low for a few ms

well, 40ms for a write command according to the datasheet

16 polls ~ 11ms

Asmyldof

I mean, device number

crasic

8:17 PM

204a

Asmyldof

huh, they didn't make any new numnbers?

When it just came out I think they had 204 without the A that I sampled?

What'd you mean with pre-empting? Your controller leading the request, data leading the clock or ?

No! wait! The first SHA I ever held started with a 1?

Ugh. My brain stores only stuff it uses...

crasic

Yeah SHA 204 is an upgrade for 1 something something

204a is a revision bump that is supposed to pin compatible

its a die shrink effectively

Asmyldof

Hm

But, can't you keep polling it, or am I misremembering that?

Or did they change that?

crasic

You can

we were timing out earlier than we should

their logic is "wait minimum time, check for read, then poll until max time, resync, try again, if failed return err"

Asmyldof

I seem to remember it even keeps resending the same stuff until you send another command, but that may have been limited to none sensitive commands

crasic

8:32 PM

we never give it a chance to respond and consistently underestimating elapsed time for timeout checks

Asmyldof

:-D

crasic

also stupid things like running the program through ssh would work sometimes, but from a remote script it won't

why: because of preemption due to print statements delaying the logic

intermittent bug finding at its best

Asmyldof

Right, well, that's

yu[

yup*

One of the more funny things in programming that spans just about all the alnguages

"My timing is f'ed up"

> "what did you do?"

"I added a debugging printf"

> "There's your problem"

(or printf --> whatever it is in the language)

crasic

IO queue slaps you

Asmyldof

Awesome thing in Altium, for example

If you do a change report pre-check on my PC: 0.1 second

Same report, execute: 4s

Difference? On screen log that cannot be disabled

:-D

crasic

8:36 PM

hehe

Asmyldof

Someone should make a mute tool

that just queue --> /dev/null for every stdout call

crasic

lol

yeah I was gonna say you can find the fd for stdout for that child process in /proc

and redirect it

Asmyldof

Well, yes, but not in Windows

Which is a problem if you are both Altiumming and Atmelling and Windows devving for customers/employers

not just both

but allathemming

crasic

I've been 100% linux for personal systems for a few years. Starting a job with windows machines means I now need to know the intricate details of cygwin just to maintain my work flow

Juan

10:23 PM

Help, please!!

0

Q: JFET - Pinch off voltage value

I have a JFET channel N and I have N_A, N_D, V_TH and the width of the channel without any polarization applied. I need to know the cut-off tension. The cut-off tension is the pinch-off tension, isn't it? I know that I have to solve when I_DS=0. When I_DS=0, V_GS=V_P. And, as the channel is N, ...

Anonymous

10:35 PM

@crasic I'd feel the same... but make it worthwhile and learn PowerShell: it's not bad

Asmyldof

10:55 PM

@crasic The joys of having an all SSD laptop :-) I only have a virtual machine for what I don't feel like hard-installing. Switching over to Debian or Ubuntu (yes, both! shutup!) from Windows or back takes less time than starting something like virtual box now

Only 4 months ago I did nearly everything in virtual box. Either in Windows because I also needed Adobe, or in Linux because I wanted to compile loads of nix-work on all threads

Also... I just installed MS Office between my last message and this one, because DOCX

I should become Samsung SSD spokesperson

crasic

11:55 PM

@Asmyldof I mean I run a Xen hypervisor occasionally, but generally just haven't had the need for windows. Since we use windows only utilities and I love me a POSIX shell for editing I make do without vm's

Transcript for

Electrical Engineering