Electrical Engineering

MLM

03:23

Happy almost over Easter

Nick Halden

04:27

did our site do anything for april fools?

I just noticed a pretty poorly implemented april fools joke on stack overflow...

made me think i had a virus for a little bit -_-

PeterJ

05:00

@NickHalden, only thing I noticed on EE was the "chat with an expert", was that what you saw on SO? (I noticed they had the same)

MLM

05:43

@PeterJ just got that message as well

night

PeterJ

Good night. I thought it was a new feature to drive a few more people to chat at first until I tried it.

jippie

08:17

good morning

What is this "Want to talk to an expert" pop up lately?

PeterJ

08:56

@jippie, you should try it, I got a good answer to my question "Dropped my iPhone in bucket, how to fix?"

jippie

@PeterJ but no matter what question I click on it, I apparently (considering the photograph) get the same expert. what guru must that be that has so much time to spare to answer so many different questions.

@PeterJ what did the expert answer?

PeterJ

@jippie, tomorrow they are sending me their lat/lon so they can install Linux on my iPhone to fix it. I asked for an address but that was difficult, so I suggested that the UPS guy would have a GPS. I should have saved the chat log I got at the end of the conversation.

jippie

09:30

?

@PeterJ Are you saying TS is the expert?

PeterJ

@jippie, trust me, whoever it is the guy is a real pro. Try it now with your ZCD question / project, you'll get an answer within seconds.

jippie

ah is it an april fool's thing?

PeterJ

Yes so now's the perfect time to ask those "Dropped my iPhone in bucket, how to fix?" questions without any downvotes ;-)

P.S. Just a bot, so it is funny to drop in some random things and see what comes back

jippie

10:32

You: How do I measure output impedance?

Expert: I don't know.

some expert

Rick_2047

11:46

hello *

PeterJ

@Rick_2047, Hi but about I'm to head off it's getting late here. You'll have to take over as the ask an expert ;)

Rick_2047

i am not an expert

PeterJ

12:01

That's no attitude, you can be an expert in anything as long as you sound authoritative ;-)

Rick_2047

well.. argument by authority is my favorite logical fallacy

I am an expert then

do you knw why I am an expert? because I say so, and I am an expert in knowing if I am an expert or not

Rick_2047

12:15

hey @AnindoGhosh

Anindo Ghosh

Hi :-)

Rick_2047

what are you upto?

jippie

@AnindoGhosh you foolish old man! you got me worried! where have you been?

@AnindoGhosh I have my Stellaris LaunchPad working

a bit

Rick_2047

@jippie stellaris is 32bit right?

jippie

@Rick_2047 yes

Rick_2047

12:24

@jippie using it for that project you were working on?

jippie

@Rick_2047 planning to, but programming it is not as trivial as programming AVR

Mainly to do with the fact that the AVR toolchain for Linux is mor mature than the Stellaris toolchain.

Rick_2047

@jippie is stellaris toolchain proprietary?

jippie

not the one that I use :)

Rick_2047

proprietary toolchains usually mean that linux support is going to suck

jippie

A lot is open

Rick_2047

12:36

nice decision

jippie

but large parts of the stellarisware is more like demo quality than a good point to really start from.

so it needs a fair bit of figuring out how to work with it

Rick_2047

is it a new chip?

i think it is

jippie

for example, you cannot create your own project outside the stellarisware tree, because some paths are hard coded in the makefile

I believe a year old or so.

Rick_2047

yeah, then its pretty new

jippie

13:01

what is the difference between a .c and a .h file? @Rick_2047

Rick_2047

13:12

@jippie .h is header file, it contains prototypes and contants, such things

@jippie .c is source, it has actual code

jippie

ok, .c I understand

but where does the contents of .h come from?

Rick_2047

they are written in a .h file

the .h file will only have prototypes

the fucntion definition will reside in a .c file of the same name

jippie

but why do I need both?

Rick_2047

because .h file does not know what exactly to do. the .h file only has information about name of the function and the datatypes it takes in

the .c file has all of these definitions about what exactly to do after you call the function

@jippie, btw, it is not nessasary to have a .h file. You can have a .c file and just include that

jippie

13:34

so what is the use for including an .h file?

Rick_2047

it helps you keep things better organized

all the macros, header includes, defines and prototypes go into .h, all the real logic goes into .c

also it helps you hide your code if its proprietary

MikkoP

Hi there! Anyone here who knows Arduino or especially NPN transistors?

Rick_2047

@jippie like you can go and precompile your library into a .a file and only distribute the .h and .a file

@MikkoP what do you want to ask?

MikkoP

Hi Rick. I have a radio controller stolen from my RC car's controller. To move forward I need to connect 4,5 V wire to ground. I've connected the 4,5 V wire to NPN collector and the emitter to ground. Now when I connect Arduino to the base the current starts flowing even I don't apply any current there

Rick_2047

is the circuit isolated right now? What is the code inside the arduino? is the pin low or high?

MikkoP

13:39

The isolation is fine. At the moment I just use digitalWrite to set the pin 8 low on Arduino.

Rick_2047

ok

which npn transistor is this?

MikkoP

It's BC547

Rick_2047

okey

where are you taking the output from?

where are you measuring?

MikkoP

Arduino is gettin power from different source than the radio controller because the controller wants 9 V. The grounds are connected to each other. I made sure the voltage is zero on the base by using a multimeter to measure it. I connected ground to ground and the voltage wire from the multimeter in the base pin

Rick_2047

measure voltage at collector

MikkoP

13:45

.. or base leg

Says -5 V

Wait

Rick_2047

are you holding the multimeter right?

MikkoP

Around -2,8 V

Sorry for that, no minus in there, my bad

Rick_2047

are you sure you have connected the transistor right?

can you provide a picture?

jippie

@Rick_2047 don't really get it when both the .c and .h files are distributed together, but never mind I'll take it as a fact for now.

MikkoP

Sure, just a moment

Rick_2047

13:48

@jippie hmm... my failiure to make you understand

jippie

@Rick_2047 No, I'm just beginner when it comes to C

Rick_2047

look at it like this, .c files are the actual source, .h files are information about the source

@jippie in most good libraries .h files have alot of comments explaining what a function does, while .c files have a lot of comments says how its done

MikkoP

Hope these are clear enough mikko.peltoset.fi/circuit%20(1).jpg mikko.peltoset.fi/circuit%20(2).jpg

Rick_2047

what are the green blue and black wires?

MikkoP

They come from the controller. Blue is ground, black and green are 4,5 V. Connecting green and blue the car goes forward, black and blue makes it go backward

Rick_2047

13:54

then your configurations is wrong I guess

MikkoP

Do you have something in mind?

Do you might know what these mean? Two of the transistors say BC547 and on the next line there is 943 and B on top of one of the legs. One of them says BC547 and on the next line 410 and the same B

jippie

14:26

BC547 is a quite common transistor

@MikkoP you can easily find the datasheet for them through google or whatever search engine you like. Don't know what 943 and 410 means, they're probably production codes.

B-suffix is again mentioned in the datasheet

I'm not terribly impressed with Stellaris LaunchPad / Stellarisware. Several examples compile but just don't seem to work.

Nick Halden

14:43

sup

Nick Halden

15:03

hey whenever a mod gets a chance @Kortuk @W5VO can you tell me more about the commitment stage? it's weird the info it asks for...

Kortuk

@NickHalden It is for a launching site, it is wondering what your level of expert will be fore the site so that it has some idea of what level you will be on the site.

Nick Halden

@Kortuk ok and as for like full and email?

full name*

i might just wait until arduino is already a site, and then join

Kortuk

@NickHalden it shows your full name and takes your email to email you updates. The email is not shared.

Nick Halden

@Kortuk hmmmm ok

Kortuk

@NickHalden area51.stackexchange.com/proposals/49538/…

Scroll down, you can see what mine looks like, and I gave it my real name and email.

Dont worry, SE is very good about private information.

Nick Halden

15:07

@Kortuk haha, beginner or learner! nice...

Kortuk

@NickHalden as was discussed at the meetup when I tried to get a simple Arduino program running, I dont know arduino

Nick Halden

@Kortuk oh.. interesting

Kortuk

I would hope that once I get through the IDE nuances I can very quickly bridge the gap to the rest and be pretty advanced quickly, but as of right now I am pretty new.

@NickHalden I was having all kinds of issues, which @jippie told me how to turn on more detailed error logging, and the java errors were the ones I immediately recognized when I last used java to use a com port that was already taken, and I just had to release the com port.

Nick Halden

@Kortuk ah, fair enough. yeah i've never really had any problems with it until i tried to modify the bootloader and kind of broke it, then tried to reflash the original and screwed up the fuse settings... took me like 3 weeks to get it back to operating condition

Kortuk

@NickHalden I want another arduino so I can make a programmer from it to start doing goofy things.

Like modify the bootloader.

jippie

15:13

@NickHalden you'll miss out on the beta badge!

Nick Halden

@Kortuk you can always use a normal AVR programmer

the like the mkII

@jippie oh wells

Kortuk

@NickHalden price?

jippie

@NickHalden you should have heard him during the hang out ... @Kortuk is really a beginner when it comes to Arduino.

(and Windows)

(and serial COM ports)

(and Google hangout)

(and connecting ethernet shields)

(...)

;o)

Nick Halden

@Kortuk like $20

@Kortuk better yet get the avrtinyISP as a kit from adafruit

Kortuk

you are a smart arse @jippie

@jippie I have written my own server apps that dealt with serial ports well

!

jippie

15:20

@Kortuk picture or it didn't happen.

Nick Halden

@Kortuk my boss just finished writing a serial port bootloader for one of our devices, it's an xmega chip so pretty similar to the arduino bootloader

jippie

@Kortuk I use a spare Arduino to program my AVR's. Works like a dream. I use a screw shield for it, combined with a small breadboard.

The only thing I sometimes miss is the ability to use debugWire (in circuit debugging/single stepping)

Nick Halden

@jippie you can't use the PDI interface for that? or does the atmega328 not support that...?

jippie

@NickHalden what PDI interface?

Nick Halden

@jippie avrfreaks.net/…

Kortuk

15:32

haha.

jippie

PDI is the name for debugWire on XMEGA?

The Photon

16:26

Could there be a better question for April 1?

1

Q: What's the use of tantalum resistors in audio circuits?

I've been looking at some "pro audio" sites and saw that tantalum resistors are often mentioned with claim that they somehow improve sound quality, but I've been unable to find any reasonable descriptions for discrete component operation that don't trip my audiophoolery alarm. So is there any re...

@jippie Still wondering about this?

@Kortuk, WTF is the "chat with an expert" box that appeared when viewing a question?

green_leaf

i just clicked it....

jippie

16:41

@ThePhoton well yes, but I think I miss some fundamentals because of the fact that I just picked up programming C and am basically learning on the hobby job.

@ThePhoton you are immediately connected to my tablet.

The Photon

@jippie Header files get included in all the C files that will use those functions, so that the compiler knows the calling convention (input and output types) for all of the functions.

C file contains the actual definitions of the functions, so the compiler only sees those (and generates object code for them) once.

By "included" I mean copied and pasted in place by the C Pre-processor.

Remember this is late-1970's compiler technology.

jippie

I wish we were able to send a notification to the professor when someone just copies a homework question here and copies the answer in his homework.

@ThePhoton I know I have to install header files when I want to compile stuff on Linux. Usually called dev files, from a related project.

The Photon

Yes, if you don't have the .h files, C will assume every function has the convention int f(...)

And I really mean ..., a variable args function.

Kortuk

@ThePhoton that is why I asked if it was us.

jippie

but I was trying to compile some stellaris stuff earlier today and it had the .c and the .h file next to eachother in the same directory.

Kortuk

16:46

@ThePhoton Forgot it was 4/1/2013

The Photon

Did you use '#include <file.h>' or '#include "file.h" '?

jippie

@Kortuk no it is 2013-04-01

Kortuk

@jippie maybe 1/4/2013

jippie

@ThePhoton eh ... I just typed make

Kortuk

I knew someone would say that

The Photon

16:47

@Kortuk Didn't see where you discussed it before.

jippie

I believe there was an xcde orsomething cartoon on it

The Photon

@jippie Oh...

jippie

@ThePhoton Have to do the kitty litter box before it gets dark outside. Back in a moment, then I'll look for the example

The Photon

Sounds like a compiler config issue, but I dont' even know what tools you use for Stellaris. Is it gcc?

jippie

I use gcc, yes

@ThePhoton hmm ... I have two examples, both compiles, but neither worked when I flashed it

For example the qs-rgb example

qs-rgb.c:#include "qs-rgb.h"

it includes its own header file?

The Photon

16:57

@jippie Yes. To make sure the header file and the C file match.

If the header file had int f(double y) and the C file had

int f(float y) { ... },

jippie

`-rw-r--r-- 1 jhendrix jhendrix 21142 Sep 6 2012 qs-rgb.c`
`-rw-r--r-- 1 jhendrix jhendrix 3829 Sep 6 2012 qs-rgb.h`

The Photon

all heck would break loose.

jippie

@ThePhoton ok, I understand that

The Photon

Quote marks form is right when both files are in the same directory.

jippie

but why a header file is i have the source c file too, which in fact is the main source code file that is being compiled

The Photon

16:59

Sounds like your bug is an actual error in the files, not just having the files in the wrong place.

@jippie 1970's compiler technology.

Allows compiling each C file to a separate object file.

jippie

m

The Photon

And not having to recompile everything when you just made a change in one place

jippie

@ThePhoton I think I switch to java

The Photon

Sorry I'm no help with the actual bug. Hope I clarified a little bit about H files. I'm off to work now, though.

jippie

I could do with a peer review:

1

A: Input and Output Impedance of a BJT

Measuring input/output impedance is little more than calculating the resistors in a voltage divider. Consider the following two situations: simulate this circuit – Schematic created using CircuitLab Important is that the whole circuit is not clipping, so the voltage \$U_i\$ is small...

thnx@ThePhoton yes you clarified a bit.

Rick_2047

17:40

Hello *

Kortuk

@Rick_2047 Hello

W5VO

@Kortuk openimpulse.com/blog/products-page/product-category/…

Rick_2047

@Kortuk i missed the hangout maan

that sucked

Kortuk

@Rick_2047 We can do another. I may just make a standard one every saturday, early like that so everyone might be able to attend.

and then we can bounce another around to get more coverage.

jippie

MikeVfromJoisey

1

pcb pcb-fabrication power-supply voltage-regulator

That user is leaving strange answers.

Don't believe it it TS though.

Hmmm now I am in doubt if I read correctly.

Kortuk

17:48

not TS from the writing, just someone that needs to have a little site explanation it seems.

Rick_2047

did you guys hear? there is a labview library for arduinos?

can there be any higher level of abstraction from the circuit?

jippie

@Kortuk maybe i just need to re-read couple times :)

Kortuk

@Rick_2047 labview for embedded is really really bad

Labview has lots of bloat and you normally just get overspecced hardware to deal with it

jippie

@Rick_2047 I'm unfamiliar with labview. What is it used for / useful for?

Kortuk

I went to a labview for embedded presentation at NI week and the guy teaching effectively said it did not work.

Rick_2047

17:50

@jippie its a graphical programming language which just abstract out everything

Kortuk

LabVIEW

LabVIEW (short for Laboratory Virtual Instrumentation Engineering Workbench) is a system design platform and development environment for a visual programming language from National Instruments. The graphical language is named "G" (not to be confused with G-code). Originally released for the Apple Macintosh in 1986, LabVIEW is commonly used for data acquisition, instrument control, and industrial automation on a variety of platforms including Microsoft Windows, various versions of UNIX, Linux, and Mac OS X. The latest version of LabVIEW is LabVIEW 2012, released in August 2012. Dataflo...

Rick_2047

@jippie you just drop in pretty looking blocks on a block diagra and we have what we want

Kortuk

the engineers there are rock solid and make some nice hardware though .

Rick_2047

@Kortuk when was this?

Kortuk

@Rick_2047 I went to NI week 2 years ago.. no, 3 years ago.

It works, it just has TONS of bloat

for very tiny simple programs it added many kB of overhead

jippie

17:51

@Rick_2047 I feel out of control already :-p

Rick_2047

@jippie you are, but of course you can drop down to lower levels.

especially when controlling instruments

I effectively wrote the drivers for many devices

@Kortuk oh it has changed a lot since then. I have read that they actively started to focus on removing bloat

rawbrawb

grEEts all

jippie

I've used NI libraries ones to control some instruments ... but it was in pascal if I remember correctly, or basic...

Kortuk

@Rick_2047 Yeah, i would still not suggest using it for a micro where any bloat counts, but I can take a look again.

Rick_2047

@jippie what instruments wer they?

@Kortuk of course, that is why I was amazed at this move

but its a nice way to get cheap labview

jippie

17:54

@Rick_2047 Wavetek Stabilock 4032 and a Philips/Fluke DVM with a couple hands full digits

Kortuk

@Rick_2047 They want everyone to use it. If you have it working and it saves dev time and makes the product you need, who cares about the bloat, it just makes it easy to not let the product work.

jippie

is it free to use?

Rick_2047

@Kortuk yeah, so this NI guy this time on the Amp Hour and cris explained it like that

@jippie it is the opposite of free, as far away from free that you can be

jippie

I'll stick with C then

Rick_2047

@jippie this is not a product targeted at you

@jippie @Kortuk but a really nice price point sparkfun.com/products/11225

you get an arduino and labview for 50USD

as cheap an NI product as ever

Kortuk

17:58

@Rick_2047 I mean, that is the world of engineering. Your end goal is a good product at low cost.

Rick_2047

actually this product is for non electronics engineers

anyone used stm8 controllers?

Kortuk

@Rick_2047 it is for both.

Rick_2047

18:17

but an electronics engineer would always like to go down and dirty on this

i for one would never use LV for my controllers

but I would see how this could lower the barrier for entry

jippie

so what would be the typical use case for a labview powered arduino?

Rick_2047

some scientist who wants to use several temperature sensors in his/her project. they buy this and several lm35's and stick them at several places, recieve waveform from the arduino and get squiggly lines on a graph

jippie

I don't have money for several LM35's. LM35 is so nineties btw

Rick_2047

these are physics majors we are talking about

google temperature sensors, LM35 is cheapest result

and available everywhere

jippie

i refuse to use 20+ yr old technology.

Rick_2047

18:28

you are not physics major who google "temperature sensor"

jippie

I would duckduckgo for "temperature sensor"

Rick_2047

now that is way too much hipster for me

Kortuk

18:53

@Rick_2047 I know and am close friends with multiple engieners there and I am proud to call those men and women EEs. They do a solid job.

The Photon

20:24

@jippie You're the local Unix guru?

jippie

@ThePhoton define local

The Photon

@jippie Here on EE.SE

jippie

in the last three lines of chat transcript ... maybe

The Photon

@jippie I was replying to your comment about 20-year-old technology

jippie

o.

funny

:-p

time for bed

/me is out

Anindo Ghosh

21:32

@jippie I'm back :-) And sorry about getting you worried.

Transcript for

Electrical Engineering