Electrical Engineering

abdullah kahraman

3:00 PM

@PeterJ hahhaa, yes :)

PeterJ

@ScottSeidman, what do you teach / lecture in?

Scott Seidman

@PeterJ Biomedical Engineering. I teach a Physiology course for engineers (that a non-engineer couldn't pass), and co-teach a design sequence in addition to the instrumentation cours

abdullah kahraman

This one probably? urmc.rochester.edu/people/21457371-scott-h-seidman

Scott Seidman

@abdullahkahraman Yup, but horrible photo

abdullah kahraman

@ScottSeidman Wow, how can you manage to know both about biomedics and electronics?

PeterJ

3:07 PM

Ahh, cool, I'll have to get around to uploading my pic soon...

Scott Seidman

@abdullahkahraman You just learn a few key words in each ;)

jippie

@abdullahkahraman whazzup?

abdullah kahraman

Better image, you should tell them to change it with this one, lol

I understood nothing on this page: bme.rochester.edu/people/faculty/bio/?id=75

Not even a word, lol

Scott Seidman

@abdullahkahraman Not much better, but I don't a photographer star material. Vestibular system has been engineering-oriented for decades, because its the air-force pilots who experience the system the most, and they're engineers

abdullah kahraman

@ScottSeidman Couple of words now, thanks :)

jippie

3:13 PM

@ScottSeidman I want a report button for homework questions, so we can ~~betray students~~ inform teachers easier.

I had to find my own information too when I was a student.

abdullah kahraman

@jippie lol

jippie

nothing wrong with asking questions, but some students just drop the whole homework on us.

and the worst just scan the exercise from the book and put it up as a question

rawbrawb

grEEtings all!

jippie

@abdullahkahraman oh, now I see why you copied me in on that question

Scott Seidman

@jippie Great point jippie. We're constantly changing up methods as info becomes readily available. There's no such thing as a text without freely available instructors versions w/ answered questions. Great discussion, but need to sign off for a meeting. I'll be back

jippie

3:18 PM

@ScottSeidman enjoy!

Anindo Ghosh

hEEloooo all! Another long day, so I've been missing. Just got home... and now, I'm off to a party in the next half hour. Are any of you interested in Bollywood movies?

PeterJ

@AnindoGhosh, are you streaming us exclusive CAM video?

jippie

@AnindoGhosh only if there are cute girls in them

Anindo Ghosh

@PeterJ Nope... and I assure you it's not going to be worth watching.

@jippie Google "Shootout at Wadala", check who the stars are. :-)

PeterJ

@AnindoGhosh, OK, not interested then, I prefer your R2D2 impersonations :)

Anindo Ghosh

3:23 PM

@PeterJ Hahaha

jippie

@AnindoGhosh I guess the answer is 'nope'

Anindo Ghosh

@jippie Fair enough :-)

abdullah kahraman

3:35 PM

@jippie I am doing what I am learning :)

@rawbrawb @AnindoGhosh hEEy!

Anindo Ghosh

:-) Hiya @abdullahkahraman

jippie

@abdullahkahraman There should be a lock-this-question-immediately-because-it-makes-unnecessary-use-of-screendump-images

abdullah kahraman

It is amazing how cheap 2TB SAMSUNG Portable USB 3.0 hard-disks got nowadays..

ONLY $19.99!

I should say it feels heavy!

jippie

You should buy couple of them

abdullah kahraman

@jippie There are people who go and buy these and come us with complaints, as we are expert witness for a court.

@jippie Yeah, only if that tag was a little shorter lol

jippie

3:40 PM

these brass rods are expensive

yuou have the actual drive there!?

abdullah kahraman

@jippie Yeah, that photo is taken by me :)

And it is 2TB, which is 2TeraBrass

cool

Yo yo yo!

@coding_corgi y0y0y0

did you try to connect it to your pc or is that not allowed with expert witness stuff

hi @coding_corgi

abdullah kahraman

3:44 PM

@jippie I have, they have implemented a USB Mass Storage for the device and that is all :)

coding_corgi

@abdullahkahraman Shoot! Gimme a second...

Yo yo yo ©

jippie

@abdullahkahraman looks like an arduino

coding_corgi

@jippie Yo!

jippie

@abdullahkahraman I bet @coding_corgi could make the software for it

abdullah kahraman

@jippie Hahaha! That is a PCB of a USB flash drive with corrupted flash IC.

coding_corgi

3:45 PM

@jippie Did you make an Arduino Shield for a programmer?

abdullah kahraman

lol...

jippie

no, I just use a standard test shield

coding_corgi

@jippie Actually I currently don't have anything going on (meaning I have no life), so sure!

@jippie Like?

jippie

don't know what name it goes by

some come with screw terminals, some come with a small breadboard

...

abdullah kahraman

@jippie I would be shocked if you used an Arduino

coding_corgi

3:47 PM

@jippie Something like this:

And then put a ZIP socket or something on it, etc.

Sort've like this:

jippie

@coding_corgi this is mine at the moment

coding_corgi

@jippie ?

jippie

PeterJ

@coding_corgi, I'm heading off but now you've left disturbing images of unpopulated breadboards in my head, how can I sleep now???

jippie

the yellow breadboard is something esle. The blue USB cable is something else too

coding_corgi

3:52 PM

@jippie Cool!

jippie

@coding_corgi nice one

coding_corgi

@PeterJ You don't.

jippie

where did you find the one with the zif socket?

coding_corgi

@jippie They sell that at a nearby Geek Heaven (otherwise known as a computer store) but I haven't gotten one yet.

abdullah kahraman

@jippie Those cables that goes to the yellow breadboard are matched for 20MHz, right? Oh, there is no need for that, yellow is a color that also have a property to be an signal-integrity fixer :)

jippie

3:54 PM

Mind you that different AVR's have different pinout. Most are identical but several are very different. Watch out with statically wiring up.

@abdullahkahraman Everything below 1GHz acts as DC

abdullah kahraman

@jippie lol :D

jippie

1GHz has a 30cm wavelength; 100MHz => 3 meters; 20MHz => 15m.

I think the wiring is fine for a little test

coding_corgi

@jippie I don't really want to deal with jumper wires, so I am looking in to that now,

abdullah kahraman

@jippie Yeah, I was joking, lol :)

I know nothing about high freq. :(

coding_corgi

@jippie I want to put my AVR in, program it, take it out, done! No jumper wires, those drive me crazy!

@jippie Should I make a different shield for each AVR or....

abdullah kahraman

3:57 PM

I have to go!

See you all!

jippie

@coding_corgi I'd personally put a row of sockets along side the ZIF socket, so I can push in short, made to fit, jumper wires. Then if I have to program a different AVR pinout I can change the jumper wires/

Nick Halden

Hey guys I have a question for y'all

Let's say I want to spy on some high speed UART lines which are going between two MCUs

so I add a little connector between the two MCUs that allows me to tap into them

but now let's say I'm worried about my additional trace length and connector adding some ohms and some farads to the trace and affecting it's rise time etc.

What is the name of the IC that I would put on there to clean it up?

high speed buffer or something?

jippie

use a fet or opamp as probe

coding_corgi

@jippie ok...

Nick Halden

eh, i could do that... but let's say I dont want to =P
Aren't like octal buffers designed for this?

something like nxp.com/documents/data_sheet/74HC_HCT7541.pdf

?

coding_corgi

4:03 PM

@jippie Here is my current setup:

abdullah kahraman

@NickHalden bit.ly/14kifRw

lol

I'm out, bye guys!

coding_corgi

Nick Halden

@abdullahkahraman Thanks... but not at all what I'm asking

David Kessner

Hi all

abdullah kahraman

@NickHalden I know, I wanted to make you mad :)

@DavidKessner Hi, and bye!

Nick Halden

4:07 PM

@DavidKessner hey! you'll know the answer to my question =) See the last 30 lines of chat or so

abdullah kahraman

@NickHalden @DavidKessner, don't!

lol

David Kessner

@abdullahkahraman Was it something I said?!?!?! :)

@NickHalden What is the signaling standard being used? LVTTL? RS-232?

Nick Halden

@DavidKessner uhmmmm normal TTL

well actually

it's 0 - 3.3V

so yeah LVTTL i guess, or is that only for 0-1.8V?

let's called it MVTTL haha

David Kessner

@NickHalden LVTTL is generally used for 3.3v TTL, although it is a bit misleading.

@NickHalden Bit rate?

Nick Halden

to spy on them i added a connector which i just connect to an FTDI cable and then look at it on my computer

@DavidKessner currently we're operating on either 57600 or 115200

and there's never been an issue

but for the sake of the question, let's pretend we wanted to go higher to where it would become an issue

David Kessner

4:20 PM

@NickHalden Let's start with the practical side of things first. 115.2kbps is not high speed, and it is unlikely that you will need to do anything special. The added trace/wire length is unlikely to do much. The worst thing would probably be huge overshoot/undershoot that actually causes the chips to latch up and literally destroy themselves.

Nick Halden

@DavidKessner right, that's why i said for the sake of the question assume we want to go higher

David Kessner

But let's say that you wanted to go faster... Then you would use a buffer or two of some sort and insert them into the line. But the thing about buffers is that there are so many to choose from. The exact one is hard to say, since it depends on the cable lengths, the data rates, etc. Some buffers are better at driving long lines than others.

Nick Halden

@DavidKessner we're talking like a few cms here

@DavidKessner so the part that i linked to is at least reasonable... headed in the right direction?

David Kessner

@NickHalden Yeah, buffers are huge overkill for this application.

Nick Halden

@DavidKessner Agreed, was just thinking/curious

@DavidKessner i used a memory chip with an SPI clock of 4MHz once and it was very sensitive to added capacitance from putting stuff on a breadboard so that's why i was wondering.

user61389

4:31 PM

@abdullahkahraman thanks, it went well :)

David Kessner

@NickHalden I wouldn't use a 74HC part, but it would work. Just about any buffer would work at <1mbps and several cm.

user61389

@PeterJ sorry, I a now :D can I still be of any help?

David Kessner

@NickHalden Odds are that it was sensitive because you didn't have proper trace impedance and proper signal termination. Not because of the capacitance.

coding_corgi

@jippie Do you thing ARM is a good micro-controller to use after AVR gets boring (although I am far from that)?

David Kessner

@coding_corgi Absolutely! My 8th grader son used an ARM M3 in his science project!

coding_corgi

4:37 PM

@DavidKessner Cool!

@DavidKessner What did he do?

Nick Halden

@DavidKessner well the breadboard capacitance affected the trace impedance no? after soldering it onto perfboard it worked perfectly without the buffers in place so i assume it was from the breadboard...

jippie

he made it explode

coding_corgi

@jippie !

David Kessner

@coding_corgi A "drop tower" amusement park ride. The ARM controls the stepper motor to raise thing up the tower.

Nick Halden

@coding_corgi yep. that is the perfect transition. that said you have YEARS before you've exhausted AVRs

jippie

4:39 PM

ARM is quite bit more complex, but there are tools

coding_corgi

@DavidKessner Cool!

Nick Halden

@coding_corgi there are many tiers of AVRs, so once you get tired with the ATmega328 or w/e you're using now, look at the xmega line, and then even the AVR32 line. THEN move to ARMs

im currently starting to feel comfortable with xmegas and am shortly going to move to AVR32s before jumping into ARM

jippie

@DavidKessner what is wrong with two push buttons and some manual labour at that age?

Nick Halden

so i know how the journey works

David Kessner

@NickHalden It is impossible to say without looking at it on an o-scope. But capacitance, impedance, and termination all manifestations of the same thing (when you are talking about wires/traces). In fact, on PCB traces the impedance is directly related to capacitance.

coding_corgi

4:40 PM

@NickHalden What's so special about XMega?

David Kessner

@jippie We also 3-D printed a lot of the parts. He is getting good at Solidworks.

@jippie Part of the assignment said, "minimal human interaction".

Nick Halden

@DavidKessner right, ok well thanks for he info. So to sum up, a buffer similar to the one i linked would be what im looking for if this problem were to occur.

David Kessner

@NickHalden Yes.

Nick Halden

@coding_corgi they're just more feature rich than normal megas and therefore allow you to do more complex stuff and encounter more complex bugs and learn more complex things

coding_corgi

@NickHalden Like?

Nick Halden

4:43 PM

@coding_corgi like full speed USB, or a full 802.15.4 networking stack

have fun implementing that on an mega168

coding_corgi

@NickHalden Cool!

@NickHalden What are Atmel products used in? I just want to know if I am wasting my time...

jippie

cars

Nick Halden

@coding_corgi haha no, they're probably in the top 3 for most popular low end microcontrollers. definitely not wasting your time learning AVRs. Especially since 95% of the knowledge will be transferable.

jippie

i believe bmw is on avr

coding_corgi

@jippie SWEET!

@NickHalden What's the other 2?

Nick Halden

4:48 PM

@coding_corgi PIC, and then specialized 8051 combo cores would be my guess

not an industry expert here, but those would be my guess for top 3

coding_corgi

Just because seeing the modern manufacturing processing: is just to be the cheapest, and not all AVRs are so cheap...

@NickHalden Doesn't Apple have some Atmel products in it?

Nick Halden

@coding_corgi no idea. i stay far away from apple products

coding_corgi

@NickHalden What?! You haven't read Steve Jobs?! It makes you love Apple...

Nick Halden

it would not, i assure you

jippie

I think I'm going to postpone my social life with an extra month @AnindoGhosh

coding_corgi

4:56 PM

@NickHalden Ok...

jippie

@NickHalden ARM does a fairly good job lately

Nick Halden

@jippie oh ARM is killing it, but i dont put them in the same low end bin as like 8-bit AVRs and PICs

jippie

But ARM is definitely more high end than AVR

Nick Halden

@jippie exactly =P

jippie

@NickHalden totally different market share, I agree. But both used on Arduino ;o)

coding_corgi

4:58 PM

@CamilStaps The other day I was about to buy a PIC kit just because it had a battery back in it, but then I found an AVR kit with the same stuff and more, if I got the PIC kit I would've smash the tiny little PIC with a hammer, and post the picture on EE chat...

user61389

@coding_corgi I need more powers.

jippie

Arduino ~~fills~~ plugs the gap between AVR and ARM :o)

coding_corgi

@CamilStaps Powers like?

user61389

@coding_corgi burn messages

Nick Halden

ok im out for a bit

ttyl guys

coding_corgi

5:00 PM

@CamilStaps Messages like?

jippie

@coding_corgi powers like not loosing reality

user61389

@coding_corgi anti-PIC

coding_corgi

@CamilStaps Messages like crushed PICs?

user61389

@coding_corgi might be

coding_corgi

@CamilStaps Hmmm...

coding_corgi

5:12 PM

@CamilStaps take a look:

►

DA END OF PIC!

@CamilStaps It's actually kind've scary...

user61389

With 'that silly 8 bit microcontroller' I can do a better filming job than this.

coding_corgi

@CamilStaps Anyone could...

@CamilStaps Though please make a video of you destroying PIC microcontroller...

user61389

5:30 PM

@coding_corgi wasn't planning, sorry

coding_corgi

@CamilStaps ..... ARGHHHHHH!

jippie

5:46 PM

I think filming in a fire is a bit more difficult than you would expect.

coding_corgi

@jippie Just a little...

jippie

6:30 PM

The "Explain in Detail why" indicates this is homework of some sort that has been transcribed onto this site without showing the effort to arrive at an answer, if one exists at all. Voting to close, sorry. — Anindo Ghosh 3 hours ago

@AnindoGhosh don't give away our methods to figure out homework questions ;o)

The Photon

6:41 PM

Sure, T. rex is closer in height to Stegosaurus than a sparrow. But that doesn't tell you much; 'Dinosaur Comics' author Ryan North is closer in height to certain dinosaurs than to the average human.

coding_corgi

@ThePhoton Cool...

The Photon

I want the print

Also, be sure to read the mouse-over.

coding_corgi

7:27 PM

@MLM Yo!

MLM

@coding_corgi Hey

user61389

7:58 PM

Do we really need an electronics tag?

coding_corgi

@CamilStaps YES! :)

angelatlarge

@CamilStaps Yeah, it seems odd

W5VO

@CamilStaps no...

user61389

@W5VO thank you - I thought, perhaps regarding the discussion about the difference between EE and electronics it might be useful to people who distinguish that difference

W5VO

@CamilStaps It's about as useful as on-topic

user61389

8:14 PM

Lol :)

jippie

8:28 PM

Notice the transistors. Am I correct by using P-channel symbols when I port the top schematic to circuitlab for better readability?

The Photon

8:53 PM

@jippie The upper schematic has n-channel fets.

jippie

@ThePhoton thought so, the arrow in the symbol is the other way around, right?

The Photon

MOSFET

The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a transistor used for amplifying or switching electronic signals. Although the MOSFET is a four-terminal device with source (S), gate (G), drain (D), and body (B) terminals, the body (or substrate) of the MOSFET often is connected to the source terminal, making it a three-terminal device like other field-effect transistors. Because these two terminals are normally connected to each other (short-circuited) internally, only three terminals appear in electrical diagrams. The MOSFET is by far the ...

jippie

ah no bulk

The Photon

@jippie yes, the arrow is opposite if you draw it in the source leg from if you draw it in the body connection.

jippie

figures

i guess

thnx

The Photon

8:55 PM

@jippie Of course you are in Europe so you can probably find a standard that contradicts me.

W5VO

@ThePhoton I use the 'dot' for PFETs - I get fewer questions that way :)

jippie

wikipedia is in black an white, that counts as absolute proof

The Photon

@W5VO Haha, I thought that was the symbol digital guys use. (Cue Widlar poster)

W5VO

@ThePhoton Is it just me, or is a match fairly weird to use as a scale reference in that wikipedia reference

The Photon

@W5VO If I want to start a fire, I'll overheat my FETs myself, thank you very much.

W5VO

8:57 PM

@ThePhoton It is - but I like it so much more than arrows and random body connections

The Photon

@W5VO I'd repost the Widlar poster, but I see you were the last one to post it here.

W5VO

and if it's on die, the source is relative :)

@ThePhoton Digital is for those who failed transistor biasing in college :)

William 'MindWorX' Mariager

Does anyone know a good guide on how to reverse engineer an electronic device?

I've extracted a WiFi module from a wireless printer.

I've found a bit of information but no datasheets.

jippie

1

Q: MOSFET symbol - what is the correct symbol

I've been on this site now a couple of months and I notice various symbols used for MOSFETs. What is the preferred symbol for an N Channel MOSFET and why?

mosfet

I'll leave the honours to you :o)

William 'MindWorX' Mariager

I'm almost positive that it's a USB device of some sort. It has five wires. Four of them together and one separate that was connected to the metal casing.

Also, this page has some limited information: wikidevi.com/wiki/Foxconn_T77H054

Problem is, all five wires are blue. So I have no clue what's positive, negative or data.

jippie

9:09 PM

@William'MindWorX'Mariager Don't know. USB has +5V and 0V (GND), those should be pretty easy to figure out.

@William'MindWorX'Mariager the wire to metal casing is shielding.

William 'MindWorX' Mariager

@jippie Yeah, that's what I assume as well.

jippie

shield to ground resistance will be very low

and the other two .. don't know how to uniquely identify them

time for bed