Electrical Engineering

The Photon

00:00

@inkyvoyd Same amount of information. But the rules for multiplying vectors are different from the rules for multiplying complex numbers.

inkyvoyd

At the same time though, I see a lot of j^2 terms in the explanation, which is what confuses me - it seems like we're using complex numbers to reduce the problem into just one variable, except at the same time we still use the definition of complex numbers...

The Photon

My comment way up was meant to say, you can really think of a complex number as a 2-vector with a special multiplication operator that makes it useful for analyzing/describing oscilatting systems.

@inkyvoyd In your formula, Re{V exp(jwt) }, notice what happens if V is complex.

You have Re{V} cos(jwt) - Im{V} sin(jwt) ...(double check this, I may be mixing up sines and cosines)

So both Re and Im of V matter.

inkyvoyd

you get a cos(wt)-b sin(wt) correct?

if V=a+bi

The Photon

@inkyvoyd Yes, a = Re{V}, b = Im{V}.

@inkyvoyd and yes, I shouldn't have included "j" in the sine and cosine.

inkyvoyd

Okay - what next?

The Photon

00:05

And notice the maximum value of v(t) is sqrt( Re{V}^2 + Im{V}^2 ). so again, both the real and imag parts matter.

inkyvoyd

so, is Re{Ve^(jwt)} just some clever identity?

The Photon

@inkyvoyd I don't want to say that, but I admit it's a formula I hardly ever use in day to day engineering.

If I have a signal described by a complex number, I just think "this is the magnitude", and "this is the phase"

inkyvoyd

Well, I guess the main reason I've stared at this for a few hours is because I was hoping I could justify the usage of complex Ohm's law

I can't seem to make a mental image of why we can almost treat capacitors and inductors like resistors - I guess they can be seen as time-varying resistors, but the entire concept seems to be above my comprehension

The Photon

@inkyvoyd To me, the justification is that it accurately predicts the behavior of real circuits.

inkyvoyd

Should I just accept it and see if it makes more sense later?

I mean, the results of the book

The Photon

00:10

@inkyvoyd Not sure your education level. Have you studied differential equations?

inkyvoyd

@ThePhoton Well, I know how to solve a seperable differential equation, and I have looked over the solutions of the first order and second order linear diff eqs, but I probably couldn't pop out the solution of the second order linear differential equation off the top of my head

I basically skimmed over my sister's intro level diff eq book

*the first half of haha

The Photon

@inkyvoyd That's a start.

The next thing is the Fourier transform.

coding_corgi

I am thinking about buying new headphones, I bought some okay ones for 30 bucks 5 months ago and I am thinking of upgrading...

Any suggestions? ;D Ha ha...

inkyvoyd

@ThePhoton Are you suggesting that I take a bit of a break from this textbook and read up more on that math?

The Photon

Which is basically a way to reduce differential equations to linear algebra equations with complex numbers (which, when you apply it to electronics, is basically exactly what you're asking about).

inkyvoyd

00:14

@coding_corgi the headphones I use cost me maybe 10 bucks o.o

@ThePhoton So, I just don't have the mathematical basis to understand what is going on here?

*truly understand

The Photon

@inkyvoyd I don't know if anybody ever truly understands this stuff.

But to get deeper into it, I think you need to learn about Fourier series and Fourier transforms.

coding_corgi

@inkyvoyd I currently hate mine, every time i move it gives me static, sometimes it doesn't work, they're Sony Stereo Headphones MDR-ZX100

They work pretty well

comfortable

good sound

@inkyvoyd what type are they?

The Photon

Which is normally like a 2nd-year college math topic for engineers.

inkyvoyd

Well, if the prereqs are just calculus, I'm perfectly okay with reading the "advanced engineering mathematics" book that I have on my computer

otherwise I'll read up on linear and diff eq intro classwork

The Photon

@inkyvoyd That should be a good one. Fourier analysis should be one of the main topics in a book with that title.

inkyvoyd

00:18

Will I still be able to understand "The Art of Electronics" without this mathematical knowledge?

I might just slowly read both starting this summer so I don't get bored with either

coding_corgi

@inkyvoyd That might be me... ;D I'm in 6th grade so I don't know calculus,algeraba, etc.

The Photon

@inkyvoyd I think so. If you're willing to just accept that the complex numbers predict the physical world, without needing to understand "why".

I haven't read that book for years, but from what I recall it used very little math.

inkyvoyd

@coding_corgi mine aren't even brand name I got the in-ear buds from "2XL", since I needed a pair along with a CD player for the SAT subject tests

@ThePhoton yeah, it seems to avoid all kinds of math, but does give a few calculus exercises that I'm proud to say I've eventually figured out (after a few hours)

The Photon

@coding_corgi You could be learning algebra by now...I think they were giving us algebra by 6th grade at my school.

coding_corgi

@ThePhoton Things have changed @oldschool, plus your memory might not be so sharp... ;D

inkyvoyd

00:25

@coding_corgi Also, back when I lived in Taiwan, I'd buy a pair of in ear headphones for around 3 bucks USD, and each would last like 4 months before I broke them by tangling and yanking on them while I slept

coding_corgi

@inkyvoyd Ah, I don't like ear buds, I like head phones, I listen to music basically 6 hour days im a EE and programmer, so that's a big geek

@inkyvoyd ha ha, you in college?

inkyvoyd

@coding_corgi I got my algebra in 5th grade, though it wasn't hard (just algebra 1), and it was part of an "advanced math program" - funny it also wasn't called algebra

@coding_corgi nope - just some nooby high schooler here

coding_corgi

@inkyvoyd lucky! I wan't to learn all that math so I can do all sorts of cool stuff

inkyvoyd

@coding_corgi start here - purplemath.com

coding_corgi

@inkyvoyd algebrahelp.com ill check it out, i don't know if i want to learn algebra yet tho! whats linear algerbra?

inkyvoyd

00:30

linear algebra is some algebra course that comes after calculus typically and deals with linear systems

The Photon

@coding_corgi It's a notation to write a whole bunch of equations in a single line.

Like

a11 * x1 + a12 * x2 = y1

a21 * x1 + a22 * x2 = y2

coding_corgi

@ThePhoton ah, i signed up for a coursera course on that + programming

The Photon

becomes

coding_corgi

@ThePhoton grrrrrr......

The Photon

AX = Y

inkyvoyd

00:32

I don't like matrices.

The Photon

Expandable to an arbitrary number of x's and y's

coding_corgi

@inkyvoyd The Matrix sucks, so that must explain the movie's thoughts on matrices ;D

inkyvoyd

@coding_corgi As long as you don't multiply them, find the inverse of them, or do the dreaded determinant with them I'm fine with them. Except, you seem to be doing that more than a lot of other operations in linear algebra

The Photon

@inkyvoyd Another thing that takes a while to get your head around, but makes things much simpler , and lets you solve bigger problems, once you get it (or at least accept it and understand the rules).

inkyvoyd

@ThePhoton yeah, but I learned the hard way that skimming a linear algebra textbook does not work nearly as well as skimming a intro level ODE textbook

coding_corgi

00:37

@inkyvoyd i just forgot what you said

inkyvoyd

Random question, was it Heaviside that a lot of work on this impedance concept?

Something tells me he's one of those guys that did a lot of work and gets recognition in the scientific/engineering community, but I don't know any kids that know his name

MLM

00:53

@ThePhoton The files are .c which I believe is C and .cpp is c++. I have .c files. An error is like "usb_prog.axf: Error: L6218E: Undefined symbol Device_Info (referred from hw_config.o)." - When I look in hw_config, Device_Info is being used like this: DEVICE_INFO *pInfo = &Device_Info;

Also DEVICE_INFO is a struct and defined like this: pastebin.com/4CYrfLzN in usb_core.h

coding_corgi

@MLM wouldn't classes be better option than a struct?

MLM

@coding_corgi I don't know, I didn't make this... I ran the binary file on my board and now I want to compile it myself and then edit it to add some functionality and mess around with it

coding_corgi

@MLM i mean using inheritance might be a better method, i mean the struct seems liek the guy who made it was lazy

MLM

@coding_corgi probably, everyone says the STM32 peripheral examples are crappily coded

coding_corgi

@MLM what's the end result of all this messing around? :P

MLM

01:07

I followed this tutorial which uses the adc example but I am trying to use the USB example which is a mouse that acts with the accelerometer to move around. I want to add clicking functionality with the push button. This is just to get used to USB somewhat for my USB 3.5mm Audio Interface

coding_corgi

@markrages yo

@MLM vat is da problema?

MLM

@coding_corgi no problem stated there, you just asked why

@coding_corgi Problem is this: i.imgur.com/GjOQM9w.png

coding_corgi

@MLM dat is problema

The Photon

02:16

@MLM That line doesn't define Device_Info. It defines pinfo, and says pinfo is a pointer, whose value is the address of Device_Info. But Device_Info has to be defined somewhere else.

@coding_corgi C has no such thing as classes.

MLM

@ThePhoton I added the USB-FS-Driver: i.imgur.com/Rus99Fd.png and that got it down to 3 undefined symbols

coding_corgi

@ThePhoton C++? I am thinking of something...

it's in a header

needs a ''driver'' file

then the driver is included to use the functions

MLM

So i am sure I missing a couple more library .c files for those symbols

coding_corgi

@ThePhoton you get what i mean right? Or am i going crazy?

Stacey Anne

good morning people! Question: is it standard practise for NDAs/contracts to have non-compete clauses?

coding_corgi

02:21

@StaceyAnne yo!

MLM

@StaceyAnne the only one I signed did not have one

coding_corgi

@StaceyAnne "What is this?! Some kind of joke?!" ;D

no really what is it for?

Stacey Anne

@MLM, my client has asked me to sign a really nasty one. 6 years!!

coding_corgi

@StaceyAnne :O

Stacey Anne

there are places in europe and states in the US where non-compete clauses are illegal or at least don't count

@coding_corgi, a clause saying you can't work in competition with the client for x years after contract termination

MLM

02:24

@StaceyAnne jees, if you have any hesitation then I would not

Stacey Anne

this one had direct or indirect competition

if i just sneeze in his direction, he might decide he wants to sue me. it's insane

@MLM, I don't plan on signing it

coding_corgi

@StaceyAnne why would someone want that?

in competition with the client?

Stacey Anne

In my client's words "I've spent x money teaching you how to design my product, I don't want that info available to other people"

coding_corgi

@StaceyAnne x= ? :D

Stacey Anne

so my college education and years of experience before this that you didn't pay for doesn't count?

coding_corgi

02:27

@StaceyAnne I still don't get it...

One of my first cool py programs!

it took me an hour, stretched across today

import string
import time

print ("\nStrings\n")

a = "1 + 2 = "
b = 1 + 2
c = "%s %i" % (a, b)

print (c)
print ("")

time.sleep(2);

d = string.Template("$number1 + $number2 = $number3")

n1 = 3;
n2 = 4;
n3 = n1 + n2

print ("\nTemplate: $number1 + $number2 = $number3")
print (d.substitute(dict(number1=n1, number2=n2, number3=n3)))
print ("")

time.sleep(2);

e = "this text is not capitalized"

print (e)
e = "this text is capitalized"
print (e.upper())

f = "this contains spaces"
g = "thisdoesnotcontainspaces"

It's kind of cool, and lame

Stacey Anne

@coding_corgi, what don't you understand?, He's trying to claim my brain as his IP

coding_corgi

@StaceyAnne ok, the networking ex. helped

The Photon

@coding_corgi yes, C++ has classes.

coding_corgi

@ThePhoton Ha!

@StaceyAnne you might become part of a botnet! He must me the C&C server, and who's the controller? ... See @anorton how much you can learn in that Malware course? I failed the first test, im going to try again, but anways, iz eazy pezy

The Photon

@StaceyAnne Sounds bad.

What industry?

@StaceyAnne Also, an NDA shouldn't say who you can't reveal stuff to...it would normally just say you can't reveal it to anybody, competitor or otherwise.

If you have an NDA, and you go to a competitor and reveal the first guy's trade secrets, you already violated the NDA without having to have a non-compete on the work contract.

But maybe he thinks a non-compete is easier to enforce.

Stacey Anne

02:45

@ThePhoton I already am obligated to not give his confidential stuff away, and there is a clause about how everything I design is his.

He just also wants me to not work for a competitor for 6 years

which seems crazy, since I would have to re-design anything from scratch in any case

The Photon

@StaceyAnne It sounds like a contract to walk away from...but of course I don't know how flexible your skillset is, how broad the guy interprets the idea of "competition", etc.

Stacey Anne

this is the thing, I started working for him without this for the past 9 months. and now he's woken up and realise he doesn't want me to work for the competition

we have an nda, but it's the standard non disclose IP thing

so now he wants me to sign a stircter nda with all of this extra stuff, 9 months into the project, and backdate it to say that It starts the day i started

I'm saying no, sorry, and asking for more money

4

coding_corgi

@StaceyAnne ah ha ha!

The Photon

@StaceyAnne Where I work, when we write an NDA, except for special circumstances it won't last more than 3 years. And it will always have specific start and end dates and a list of topics covered.

Stacey Anne

@ThePhoton, that sounds about right, the ndas I've signed in the past have pretty much been the same. except this one

coding_corgi

03:14

Hasta la vista!

Anindo Ghosh

03:26

@StaceyAnne Having reviewed quite a few NDA / non-compete contracts, and signed a few from time to time, here's my $0.02: If anyone is asking you to sign an agreement or a contract that would prevent you from obtaining productive work in your area of expertise, for any period of time, the same piece of paper needs to also be guaranteeing you the lost earnings, or a mutually agreed part thereof, as compensation through said period (or as a lump sum).

@StaceyAnne It's otherwise infringing upon the right to make a living, guaranteed in constitutions of many countries.

@StaceyAnne What works in your favor is this: No contract is valid unless it is mutually beneficial. You have been doing work under terms xyz and clauses abc, whether implicit or explicit. Any change of such terms have to be sweetened such that the mutual benefit factor is accounted for. Else the contract is automatically null and void.

@StaceyAnne Were I you, I would either bring in a company law / contracts lawyer to review and annotate the document, which you would then send back to the client, or would just walk away, explicitly invoking (and documenting to them) unacceptable change in terms of agreement. That way, it would be difficult for them to even demand hand-over other than work already delivered.

"What your new contract translates to is, I cannot work for a living in my proven area of expertise for the next 6 years. That is acceptable to me if you compensate me for the loss in earning over said 6 years. Please make the check out to Stacey Anne, and the signed amended agreement will be in the mail as soon as the payment clears. Thank you."

OK, that was a bit more than $0.02.

Stacey Anne

03:45

haha, thanks @AnindoGhosh

@AnindoGhosh, I guess it's also a matter of how much work I can find in the FPGA world. I specialise in firmware,. So I probably would be able to find alternative work. But If every single client asked me to sign a non-compete clause, I would definitely run out of industries in which to work. So I can't garentee that this is going to do damage to my ability to earn income, but at the same time, I want the freedom to be able to do work without having to worry about beaching an non-compete clause

Also, this one was particularly evil. it was direct or indirect competition, for the whole of north and south america, for 6 years

Anindo Ghosh

@StaceyAnne But since you cannot guarantee that it will not harm your right to earn a living, that's what counts. Each side of any contract reviews solely to cover their interests, so don't need to think on their behalf. Also there is a standard non-compete compensation strategy that some people use, I'll tell you after breakfast.

Stacey Anne

@AnindoGhosh, and he said that he was "letting me off lightly, it's ususally 10 years!"

@AnindoGhosh, thanks

Anindo Ghosh

04:53

@StaceyAnne So yeah... when you get hit with a non-compete in exclusive engagements (contract or full-time employment does not matter), one clause that I have seen is a recompense with a rider: The client agrees to pay compensation at current contract rate for as long as employee / contractor is unable to obtain work within the constraints of the non-compete clause. Very difficult to implement, but usually shakes up the client enough to get some sense.

jippie

morning @all

Anindo Ghosh

Hiya @jippie

Stacey Anne

@AnindoGhosh, I imagine that's also quite a good way of ensuring job security - if they have to pay you in any case, they might as well pay you to work

@jippie, mornin

`

Anindo Ghosh

@StaceyAnne Generally the non-work compensation is a lower rate than the work rate (which includes unstated implicit expenses incurred in the execution of the work), but yes, that's a knife that cuts both ways.

abdullah kahraman

05:55

Hi!

@jippie Wow, you are an early bird!

jippie

@abdullahkahraman getting new windows today

abdullah kahraman

@jippie Congrats, 7 or 8?

jippie

...

abdullah kahraman

:P

jippie

windows as in my bathroom

and my kitchen

abdullah kahraman

06:01

Cool, are they PVC?

jippie

glass

duh

abdullah kahraman

@jippie Duh! Really? They are glass?

@jippie So they have no frame?

jippie

@abdullahkahraman you asked about the windows, not about the frames

abdullah kahraman

@jippie OK then, now I am asking about the frames

Anindo Ghosh

I cannot believe the sheer intricacy of the current discussion, window glass versus window frame. :-) Keep at it, I've got my popcorn here.

jippie

06:11

@abdullahkahraman they are white

abdullah kahraman

@AnindoGhosh These linux guys are always like that, cannot even bear a joke.. about their.. windows!

@jippie PVC, we go!

jippie

@abdullahkahraman I'm not afraid of bear jokes.

abdullah kahraman

@jippie So, a bear goes into a bar and says

Anindo Ghosh

One of these days, I need to get myself a powerful Windows 8 machine. While my current PCs can handle Windows 8, it would be no fun without a touchscreen, so I'll just wait till I can get a touchscreen Surface tablet or something.

abdullah kahraman

@AnindoGhosh That piece of information just killed @jippie

jippie

06:14

@AnindoGhosh will it have PVC frame?

Anindo Ghosh

@abdullahkahraman I stay away from offending people's religious beliefs, if at all I can. :-)

@jippie It will have Gorilla Glass II.

abdullah kahraman

@jippie Here we go..

jippie

now this is going to be interesting :-s I spilled quite a bit of water ... it fell along the wall down and apparently it didn't wet the floor, so all the water must be under the laminated floor :-s

@AnindoGhosh no I mean the framing, what color is it?

Anindo Ghosh

@jippie I'll let you know when I buy it :-) Probably "an attractive color", that's what the marketing blurbs usually say.

abdullah kahraman

@jippie That is bad, really bad...

Quick C question:

jippie

06:24

I hope it went under the damp tight foil aswell ...

abdullah kahraman

So, I have this function in "init.c" file, which is the source file for header file "init.h".

In this function, I am modifying a global register in "main.c"

How do I do that?

Here are the sources:
main.c : http://pastebin.com/e5m9qdLx
init.h : http://pastebin.com/8bFfXJsK
init.c : http://pastebin.com/WCeSLgf2

jippie

I don't even know how to properly spell C ...

abdullah kahraman

@jippie Just say "Yes" in Spanish.

jippie

"Yes"

in Spanish

does that answer your question?

abdullah kahraman

@jippie Perfect!

@jippie Absolutely, thanks!

By the way, the register I am modifying is: LED_register.LEDs = SYS_SRS;

And then I call the function: updateLEDs();

@AnindoGhosh Help me! @jippie is bullying me!

Anindo Ghosh

06:34

@abdullahkahraman Somehow I think that's unlikely.

abdullah kahraman

@AnindoGhosh I want ice-cream!

Anindo Ghosh

@abdullahkahraman Bad for you. Sugar + youngster = hyperactivity :-)

abdullah kahraman

@AnindoGhosh But I promise I will perform hyperactive C coding!

Anindo Ghosh

@abdullahkahraman And we sedate, older folk will have to cope with you bouncing off the ceiling and the walls.

jippie

@AnindoGhosh the hyperactivity isn't the problem, the subsequent depression is.

Anindo Ghosh

06:39

@jippie You mean the depression parents feel when trying to deal with their hyperactive kids?

@jippie Though that would have to be "precedent depression", not subsequent.

jippie

@AnindoGhosh oh yeah please go on impressing me with difficult three+ syllable words

Anindo Ghosh

@jippie Where's Google Translate [English --> Simplish] when you need it?

abdullah kahraman

lol

abdullah kahraman

08:38

2 hours later...

jippie

@abdullahkahraman you forgot the bold print

abdullah kahraman

@jippie That means I am still a grasshopper, master.

abdullah kahraman

09:10

I've found out the way to do it..

I've used keyword extern

jippie

10:19

@abdullahkahraman See I didn't know that yet.

wirespeed.xs4all.nl/mediawiki/…

abdullah kahraman

lol

abdullah kahraman

13:08

@ThePhoton You may like this video: youtube.com/watch?v=CIwlyy_KpXo

coding_corgi

13:28

Yo yo yo!

abdullah kahraman

@coding_corgi y0y0

David Kessner

14:16

Anyone awake?

W5VO

@DavidKessner no, that's why the coffy machine is no

David Kessner

@W5VO I've been told before (By Kortuk), to not worry about serial downvoteing when I think it's TS. Now I'm confused.

@W5VO And what is the downside to serial downvoting, other than having the downvotes removed?

W5VO

@DavidKessner Having your votes removed. The only thing (that I know of) that removes votes is the serial voting script

David Kessner

@W5VO So what is the proper procedure when we spot TS?

...or the new procedure...

Anindo Ghosh

14:47

@W5VO Is serial flagging a concern? (context the same).

David Kessner

15:04

...crickets...

Anindo Ghosh

15:17

@jippie Really? Lame, Jippie, lame.

jippie

@AnindoGhosh ok ok :(

W5VO

15:30

@AnindoGhosh no

@DavidKessner It's the same, just be careful about a lot of votes on one user at a time (without votes on another user). The concern is purely about having your votes cancelled, nothing more.

coding_corgi

Yo yo yo!

David Kessner

@W5VO Ok

@coding_corgi hi

coding_corgi

@DavidKessner we meet again

..

David Kessner

@coding_corgi So, Lord Helmet, at last we meet again for the first time, for the last time.

coding_corgi

@DavidKessner That is, Sir Pickles BunnyBottom ready to blow your head off, ;D

David Kessner

15:47

@coding_corgi I guess that makes you a Mawg: Half man, half dog. You are your own best friend!

The Photon

@DavidKessner I thought we're supposed to flag as spam. Enough spam flags supposedly makes a post invisible, even before a mod gets to it.

David Kessner

@ThePhoton Yes, but sometimes I also -1, so that new people to the site will not pay as much attention to his answers. Occasionally he does get enough +1's to be more of a best.

coding_corgi

@DavidKessner shut up

David Kessner

@coding_corgi Do you know the movie I quote?

coding_corgi

@DavidKessner no

The Photon

15:48

@DavidKessner Enough -1's I think also hide the answer from new users.

David Kessner

@coding_corgi imdb.com/title/tt0094012 Watch it, you'll like it.

coding_corgi

@DavidKessner naah

The Photon

@DavidKessner The lad is impervious to culture.

David Kessner

@ThePhoton Obviously the product of bad parenting.

coding_corgi

@DavidKessner nah, my parents are great... they're not geek parents, so, yeah, great parents, unlike you

David Kessner

15:53

►

coding_corgi

@DavidKessner pass

David Kessner

@coding_corgi <facepalm>

And here is the trailer: youtube.com/watch?v=uWVSVgU-I0s

coding_corgi

@DavidKessner PAAAAAAAAAAASSSSSS

David Kessner

@coding_corgi You probably didn't like Ferris Bueller's Day Off, either.

coding_corgi

16:10

@DavidKessner GRRRRRRRRRR.....

abdullah kahraman

16:48

Hahah!

Solved my programming problems completely!

Seems like Freescale team also forget two pull-up resistors on RESET and "Debug Mode" pins!

coding_corgi

@abdullahkahraman hmmm

abdullah kahraman

@coding_corgi I don't know whether they will hear me if I send them a feedback..

jippie

@AnindoGhosh do you remember that Arduino clone I got the other day, with WiFly and LEDs and sensors and stuff?

They are on sale now for € 99, limited supply.

ex VAT and postage ..

abdullah kahraman

Off the gym I go!

Bye all!

coding_corgi

17:12

@jippie yeah

@jippie ha ha

@abdullahkahraman do you mean the arcade? ;D

abdullah kahraman

@coding_corgi lol

coding_corgi

@abdullahkahraman i bet that's a work out in your lil geek mind ;D

abdullah kahraman

@coding_corgi lol, I'm out..

coding_corgi

@abdullahkahraman you said that a whil ago

W5VO

17:29

@coding_corgi must be more of a "Gone With the Wind" fan. No low-brow humor here

coding_corgi

@W5VO hmmm

coding_corgi

18:50

Yo yo yo?

jippie

void loop()
{
char *time = rtc.ReadAll();
led.LedMatrixWrite(time,10);
delay(1000);
}

what is *time here?

is it a pointer to the string? but a char seems ... short for a pointer.

what is the * thingy in this context?

it prints a date on a display like 'Monday 24/06/2013 21:01'

coding_corgi

19:06

@jippie isnt it used in like class inheritence or something like that?

jippie

...

yeah, probably possible

so what is like class inheritence or something?

The Photon

@jippie It's a pointer to the first character in the string.

coding_corgi

@jippie i bet there's a header, then a a cpp driver that get;s the time and returns it or something...

The Photon

rtc.ReadAll() is presumably returning a pointer to the beginning of a bufer that the rtc system owns.

jippie

@ThePhoton a char pointer according to the docs, but isn't a char pointer of 8 bits a bit small for a microcontroller with several 8kB of addressable RAM?

The Photon

19:11

@jippie "char *" in a variable declaration means a pointer to a char.

@jippie The pointer could be 64 bits. The thing that is pointed to is a char.

jippie

heliosgadget.nl/wiki/Helios_RTC_PCF8563#ReadAll

it seems to point to a string

The Photon

@jippie Classic C programming style. There is no such thing as a string. There are just arrays of char's.

jippie

fair enough

but still it is only 8 bits long, isn't it?

The Photon

If you want a string, you put a "\000" character at the end of the useful part of the array of char's, and you pass around a pointer to the first element of the array.

jippie

or is it an n-bit pointer to a char?

The Photon

19:14

@jippie A char is usually 8 bits. A pointer to a char could be 8 or 16 or 32 or 64 bits.

jippie

is my assumption of the size wrong

The Photon

More likely 32 or 64 bits.

jippie

yeah

on a atmega328?

The Photon

Usually all pointers are the same size, no matter what they point to.

jippie

more like 16 :o)

The Photon

19:15

And usually the size of a pointer is the same as the size of an int.

jippie

so in this case, char says something about the data that is found at pointer *time and not about the pointer itself.

@ThePhoton yeah that is 16 bits on arduino

The Photon

@jippie the name of the pointer is just time. It's type is char *, meaning pointer to char.

After the declaration, if you used *time in your code, that would mean the value at the address pointed to by the variable time.

jippie

@ThePhoton hence the ledMatrixWrite line, I see.

The Photon

@jippie yes

jippie

:) thnx @ThePhoton

@coding_corgi security.nl/artikel/46753/1/…

coding_corgi

19:32

@jippie cool, but, pass...

MLM

Heya :)

David Kessner

@MLM Hi there.

coding_corgi

@DavidKessner grrrrrr....

jippie

morning @mlm

Anindo Ghosh

@jippie Yes, I remember that clone. Doesn't mean I can afford it, even at 99 EUR. :-)

jippie

19:46

@AnindoGhosh I think it is quite expensive

add 21% VAT, package, postage, ...

Anindo Ghosh

@jippie Yeah, I've standardized on $10 'duino clones, $4 ethernet modules, and so on.

MLM

Is there a reason that a clean install of TrueStudio for ARM won't have STM32 C Project?

MLM

20:06

nvm, it is now Embedded C Project

jippie

Can't help you @MLM, sorry

anyways

time for bed

/me is out

MLM

@jippie night

jippie

clickkk

angelatlarge

22:11

I want to make a prediction: I suspect that Snowden might, after all, be on SU #150. I think he's got another... 15 minutes in US airspace?

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Electrical Engineering