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mjcarroll
mjcarroll
12:00 AM
An irrational number cannot be expressed as a fraction of whole numbers.
So, 2/3 is rational.
sqrt(2) is irrational.
Etc.
 
tina
tina
yes i understand now
 
 
1 hour later…
Feeds
Feeds
1:10 AM
Arduino power meter http://ur.ly/GZxj #arduino
Tweeted by StackElectronix on March 22, 2011 at 1:08 AM
 
reemrevnivek
reemrevnivek
2:02 AM
@Wallacoloo Yes!
6 hours ago, by Kellenjb
BAM! new site!
@mjcarroll We've been talking about it for almost a week now on Meta. You should visit occasionally! We could use more input.
Well, off to bed for me. I've got a nasty head cold, and I need to catch up on some sleep. Happy graduation, everyone!
 
Nick T
Nick T
2:22 AM
 
Wallacoloo
Wallacoloo
Anyone here have experience with writing (HID) USB drivers under windows? I am having loads of trouble with it.
 
Nick T
Nick T
2:39 AM
you need to use COM for that or can you do it in .NET now
 
tina
tina
what means by fouri series derivation
 
Nick T
Nick T
@tina You mean how to get the Fourier series for a given periodic signal?
 
tina
tina
yes
 
Wallacoloo
Wallacoloo
@NickT what is COM?
 
Nick T
Nick T
2:54 AM
@tina It's related to the Laplace and Fourier transforms, but where there are only integral coefficients (based on the harmonics of the periodic signal) instead of a function
@tina I haven't done a fourier series in a while though, but efunda.com/math/fourier_series/fourier_series.cfm and some other pages seems to be good referneces
all you need to do is get a0, an's and bn's
@Wallacoloo A Windows API library
Component Object Model
Component Object Model (COM) is a binary-interface standard for software componentry introduced by Microsoft in 1993. It is used to enable interprocess communication and dynamic object creation in a large range of programming languages. The term COM is often used in the Microsoft software development industry as an umbrella term that encompasses the OLE, OLE Automation, ActiveX, COM+ and DCOM technologies. Overview The essence of COM is a language-neutral way of implementing objects that can be used in environments different from the one in which they were created, even across machine boun...
Though I all but guarantee that you can write them with .NET nowadays. What language are you writing the drivers in?
 
Wallacoloo
Wallacoloo
Well, I'm trying for Python.
I have some trivial code that works using Python under Ubuntu. But I'm having trouble porting it over to Windows
 
Nick T
Nick T
Using code.google.com/p/pywinusb or something?
You realize that writing device drivers is incredibly OS specific, right?
 
Wallacoloo
Wallacoloo
Yeah, I suppose it is.
It's pretty confusing too XD
 
Nick T
Nick T
I'd start with code.google.com/p/pywinusb , but things like that may not expose all you need to do it
If you use some native .NET lang (C#, C++, VB.NET) you could probably do anything and everything Windows can
 
Wallacoloo
Wallacoloo
Right, but using .net would make things a little less portable, right? I don't know how good .net support is for operating systems other than Windows.
 
Nick T
Nick T
3:07 AM
"portable drivers" is something of a contradiction
 
Wallacoloo
Wallacoloo
haha, good point.
 
Nick T
Nick T
You should write the drivers so they expose the basic functions of the device (possibly in the format of an HID device or whatever) for whatever OS you want it to run on, then have your application be able to use said drivers interchangably
stackoverflow.com for questions
:P
probably a bunch of other questions you could look at anyways to help you along
 
Wallacoloo
Wallacoloo
Well, the only thing confusing me are "Reports" within pywinusb.
I've already got it locating my device
 
markrages
markrages
4:02 AM
@Wallacoloo I prefer the pyusb API: pyusb.sourceforge.net/docs/1.0/tutorial.html Simple and cross-platform.
 
Feeds
Feeds
Intefacing a PIC Mircocontroller (PIC16F84A) to two stepper motors http://ur.ly/GZNG #microcontroller
Tweeted by StackElectronix on March 22, 2011 at 4:08 AM
 
Wallacoloo
Wallacoloo
4:33 AM
@markrages I've been trying to use pyusb, but on Windows I get errors.
specifically, device.detach_kernel_header and device.set_configuration raise USBError: Operation not supported or unimplemented on this platform, and if I try and just ignore it and write/read the device, I get WindowsError: exception: access violation reading 0x00000010. I started a stackoverflow thread on it: http://stackoverflow.com/questions/5385281/pyusb-on-windows-7-cannot-find-any-devices
 
markrages
markrages
@Wallacoloo ok, good luck with that. I think the Windows HID driver may be claiming the device. The detach...() function tells Linux "hands off!"
 
Wallacoloo
Wallacoloo
yeah. I'm not so sure how to deal with the windows HID driver
 
 
2 hours later…
Feeds
Feeds
7:10 AM
How do you minimize stepper motor vibration? http://ur.ly/H0Nl #steppermotor
Tweeted by StackElectronix on March 22, 2011 at 7:08 AM
 
Kortuk
Kortuk
7:52 AM
@reemrevnivek It looks like a duplicate to me, although they are worded very differently and have received very different answers.
 
 
2 hours later…
Feeds
Feeds
10:11 AM
Is it possible to fire a spark plug from batteries http://ur.ly/H1Xz #capacitor
Tweeted by StackElectronix on March 22, 2011 at 10:08 AM
 
 
2 hours later…
Feeds
Feeds
11:51 AM
Temperature sensor for Linux http://ur.ly/H1KB #sensor
Tweeted by StackElectronix on March 22, 2011 at 11:49 AM
 
 
1 hour later…
jpc
jpc
1:18 PM
@Wallacoloo You may try signal11.us/oss/hidapi . It is in C and has only blocking calls but is cross platform.
 
 
2 hours later…
Feeds
Feeds
2:52 PM
SD card - SPI mode http://ur.ly/H1Dq #spi
Tweeted by StackElectronix on March 22, 2011 at 2:49 PM
 
tyblu
tyblu
> "portable drivers" is something of a contradiction
I like this quote.
 
Kortuk
Kortuk
I laughed also
 
tyblu
tyblu
Now, hi ho, hi ho, off to work I go, off to work .
 
jpc
jpc
3:47 PM
@Kortuk But isn't it sad that for things like USB or HID that is fundamentally the same on every platform there are no good portable APIs? Berkeley sockets are really the only exception.
 
Nick T
Nick T
3:59 PM
@Kortuk, where'd that rotary encabulator question go? move it to SciFi.SE?
 
 
2 hours later…
Feeds
Feeds
5:53 PM
Don Lancaster's Magic Sinewaves http://ur.ly/H35o #power
Tweeted by StackElectronix on March 22, 2011 at 5:49 PM
 
reemrevnivek
reemrevnivek
6:26 PM
Anybody know why there is so much lag in the feed? I think it would be much more useful if it was immediately added to the chat upon being posted.
Also, here's another "Crimp tools are expensive" gripe...
0
Q: Ghetto crimping tool for FCI "Clincher" connectors?

Robert AtkinsAfter much experimentation and some helpful answers here I've decided that FCI "Clincher" (.pdf link) parts are the right answer for adding connectors to the ends of flexible ZJ168 RGB LED strip. The parts themselves are cheap enough (< $2 each) but the crimping tool appears to cost almost US...

connector ffc
What should we do with these questions?
 
 
1 hour later…
reemrevnivek
reemrevnivek
7:38 PM
The number of beginner questions on the front page so soon after launch is discouraging. I dropped a bounty on that memory addressing question (which puts me 200 points further from regaining mod tools), but it seems like some cleanup is in order.
 
jpc
jpc
7:49 PM
reemrevnivek: I considered deleting the answer (about the gas grill spark) but really wanted to make that comment. :P
 
Kortuk
Kortuk
8:05 PM
@reemrevnivek He at the bottom of his question is actually asking a technical question about the effects of not using crimper, it is lost in the cost part. It could really use an edit.
@NickT Link me what you are asking about and I can check. I will try finding it.
@jpc I thought that was a very good answer. It may not be the communities favorite but it did need to be said.
@Jin, I really like the buffers filling in, they look much nicer.
 
Kellenjb
Kellenjb
hello!
@reemrevnivek don't quote me on this, but I believe twitter has a limit on how often a third party is able to poll for new tweets.
 
Kortuk
Kortuk
8:24 PM
Hello
@Kellenjb, in relation to deleting off topic questions, everyone with moderator rep can vote to delete once 2 days have gone by, this way it can be cleared out by the community.
 
Kellenjb
Kellenjb
@Kortuk @LeonHeller is the only non diamond mod that we have
10k rep is mod level now
 
jpc
jpc
@Kortuk Thanks, but Rory's answer was more detailed. Mine didn't really add anything to this (apart from me answering 1 hour earlier).
 
Kortuk
Kortuk
@jpc That happens, I thought you were referring to something else, my brain plays tricks. Still, if you feel someone has gone above and beyond you always have the right to remove.
 
jpc
jpc
btw. Am I right that you cannot easily "reply" to a person here instead of one specific chat message?
 
Kortuk
Kortuk
@Kellenjb Point taken.
 
jpc
jpc
8:30 PM
@Kortuk And that is what I did. :)
 
Kortuk
Kortuk
@jpc It is really hard to reply to someone here if they have not been here in a while. Just type the @ and start typing my name and it should have autocomplete.
@jpc, if there is no autocomplete then they have not been here in time.
@jpc, and you have to find a message of theirs and click on the arrow.
 
jpc
jpc
@Kortuk Oh. Nice. I missed the autocompletion and especially with "reemrevnivek" it was quite hard. :)
 
Kortuk
Kortuk
@jpc, it autocompletes for me after 2 letters for reem.
 
Kellenjb
Kellenjb
I do the same thing for @reemrevnivek :-) damn you kevin
 
W5VO
W5VO
Later, @reemrevnivek wonders why he has 200 new messages
 
jpc
jpc
8:32 PM
Too bad for @reemrevnivek. :P
 
Kortuk
Kortuk
@Kellenjb, I lol'ed. @W5VO, then I lol'ed again.
@reemrevnivek.
I felt left out.
 
Kellenjb
Kellenjb
i really love the chat desktop notification!
 
W5VO
W5VO
@reemrevnivek will have to look through a lot of chat messages to figure out what's going in
I know when I see them, I always think someone's left me a comment, and then I'm disappointed
 
Kellenjb
Kellenjb
any of you guys use IRC chat rooms before?
 
W5VO
W5VO
yes
 
jpc
jpc
8:34 PM
@W5VO It would be better if we talked about something completely unrelated and then plugged his name in random places from time to time. :P
 
Kortuk
Kortuk
@Kellenjb Tell me how I get this.
 
Kellenjb
Kellenjb
/me liked irc
 
Kortuk
Kortuk
@jpc agreed at @reemrevnivek
 
jpc
jpc
@Kellenjb of course. :)
 
Kellenjb
Kellenjb
\me or was it that?
 
W5VO
W5VO
8:35 PM
yes, I wish /me would work
 
Kortuk
Kortuk
@W5VO it is like an old friend is missing.
0
A: Have 60A 220V circuit, want to use one 110V leg of it. Can i?

jpcJust as Billy ONeal said, you should be OK. Especially since the valve probably does not need a lot of current. Caution: I am from Europe so I have no personal experience with your system.

This would have made a better comment.
 
Kellenjb
Kellenjb
@Kortuk I am not sure if its in other browsers, but in chrome there is a "enable desktop notifications" link on the right side. If its enabled you get a little pop up in the bottom right corner of the screen when someone @s you
 
Kortuk
Kortuk
@Kellenjb, damnit.
@Kellenjb, but I love my firefox, I have for so many years.
 
W5VO
W5VO
@Kortuk @Kellenjb yeah, the tab shows the number of messages you've missed, and * if you've been @reemrevnivek mentioned.
and it plays a little sound as well
 
jpc
jpc
@Kortuk I had the impression that comments are for clarifying questions and not half-assed replies. :P I would delete this one but nobody else mentioned the power consumption of the valve.
 
Kellenjb
Kellenjb
8:38 PM
@Kortuk I used it for a long time, just recently switched. Still have a few sites that i have to switch back to FF, but almost all work fine in chrome now.
 
jpc
jpc
@Kellenjb so now you are voulnerable to a DDoD? (Distributed Denial of Desktop)
 
W5VO
W5VO
Heh... you can't loose rep for being a smart ass with the comments
 
Kortuk
Kortuk
@jpc you can post a comment on another answer to add information to that answer, unless you do not have the rep.
@W5VO You can always loose mod rep, and that is harder to earn.
 
Kellenjb
Kellenjb
@Kortuk I also have my bookmarks synced between computers in chrome
 
jpc
jpc
@Kortuk But my "answer" was the first one. :P
 
W5VO
W5VO
8:40 PM
@Kortuk How do I use or measure that?
 
Kortuk
Kortuk
@Kellenjb I started to do that in firefox then realized I like different links
@jpc Ha, I thought billy oneil was a poster and was not paying attention. Mock me later
@W5VO Say something really stupid and see if we 1 day ban you
 
Kellenjb
Kellenjb
hahaha, just had my fiancée tell me that she wants to switch to verizon so she can play angry birds.
 
Kortuk
Kortuk
like @tyblu tron comment <3
 
W5VO
W5VO
@Kellenjb How does that affect angry birds?
 
Kortuk
Kortuk
@Kellenjb I have AT&T and I can play angry birds. tell her to use sideloader pro.
@W5VO, some providers will block apps.
 
jpc
jpc
8:42 PM
@Kortuk Right! What is it about the Tron costume? :P
 
Kellenjb
Kellenjb
@Kortuk she's been trying to get wifi download to work and it hasnt been so shes mad
 
Kortuk
Kortuk
@Kellenjb haha
@jpc I told tyblu I did not really like startrek, he made the comment that is over on the starred comments list, then on his next comment asked people to star it.
 
Kellenjb
Kellenjb
@W5VO Amazon Marketplace is blocked on AT&T and Angry Birds Rio is on it
 
Kortuk
Kortuk
Angry birds rio?
Looking it up
 
W5VO
W5VO
@Kortuk Angry birds visit Rio de Janeiro
 
Kortuk
Kortuk
8:45 PM
My phone is hard blocked from installing anything not from the android store. AT&T can die in a fire.
@W5VO, smart ass.
 
Kellenjb
Kellenjb
 
jpc
jpc
@Kortuk Funny since this was once the main Android vs. iPhone argument.
 
Kellenjb
Kellenjb
@Kortuk except the download restriction note of "AT&T is working on enabling purchases from the Amazon Appstore in the near future"
 
Kortuk
Kortuk
@jpc, it is fully free on everyone else, AT&T locks it down. This is not a complete lockdown, you can still load any app you want over USB.
 
W5VO
W5VO
ATT has their heads up their ass
 
Kortuk
Kortuk
8:46 PM
@jpc I had 2 iPhones, I have been significantly happier since I switched, and when it screws up I do not get told by everyone it was my fault.
 
jpc
jpc
@Kortuk Still, mobile operators suck. In Poland too. :)
 
Kellenjb
Kellenjb
ATT does it cause they want to be able to take some of the money from app store purchases
 
Kortuk
Kortuk
@jpc Everywhere.
@Kellenjb Yeah, I just sideload if I really want to, I still have had nothing I needed to sideload.
 
Kellenjb
Kellenjb
@Kortuk just didnt know how well the side loader worked with it being the amazon app store
 
W5VO
W5VO
They sell a product they cannot guarantee (access everywhere) and view themselves as essential to your daily life (so live with their whims)
 
Kortuk
Kortuk
8:48 PM
@Kellenjb you give it the apk and it goes on your phone.
@W5VO I think what the FCC is pushing for in the states in great. Forcing TelCos to act as links like ISPs do and you purchase any device you want.
First they need to get ISPs to stop being jackasses.
I am sleepy. Convincing the wife she needs to let me sleep for a night shift is impossible, she lets me sleep, she just happens to regularly try to talk to me.
So that people know, We will start going back and cleaning up old posts. Those that do not meet current criteria feel free to vote to close or just flag for us.
 
Kellenjb
Kellenjb
@Kortuk you have to side load the amazon app store, download rio from the app store, it will fail, you then have to copy the downloaded apk off of the phone so that you can then side load that. God that sounds annoying
 
Kortuk
Kortuk
hahahahahahahaahahaaha
I hate AT&T
I will change probably in a year or two. <3
 
Feeds
Feeds
Walkie-talkie transceiver http://ur.ly/H45M #radio
Tweeted by StackElectronix on March 22, 2011 at 8:49 PM
 
Kellenjb
Kellenjb
I hate estimating how long it will take me to do something
 
Kortuk
Kortuk
@jpc, I just saw you comment, I understand your question now. I need matlab to give a good answer to that. Convert the 0s to 0V and 1s to 100V and pass it though an ideal low pass filter, see what comes out.
@Kellenjb, almost as long as you spent complaining about it <3
@jpc, if you run much much faster then you need to and do that it should be redily doable, but after the first test, it needs to be tested with a realistic low pass filter, it may have its own harmonics that depend on this.
@jpc, I also like his typo on page 4 poewr.
 
Kellenjb
Kellenjb
9:01 PM
@Kortuk @jpc If you have a stack overflow problem isn't the solution just to increase the size of the stack ;-)
 
Kortuk
Kortuk
@Kellenjb, yes, if you detect it, what if it happens runtime?
0
A: Don Lancaster's Magic Sinewaves

KortukYes, this will work. He is switching at a much higher frequency then required and then he is slowly changing what percentage of time he is on 0s to being on 1s. This means that the average of the signal is slowly going to shift up. By matching his rate to the rate change of a Sinusoid he can do t...

@jpc, I wrote something up for you.
 
Kellenjb
Kellenjb
just make it super big :-)
 
jpc
jpc
@Kellenjb @Kortuk I retract my comments about stack overflows. :)
 
Kortuk
Kortuk
@jpc, on that note, I am happy to see you come back to the site again for a relatively large amount of time.
@jpc haha.
 
jpc
jpc
@Kortuk I decided that "all work and no socializing makes me a dull boy" ;]
 
Kortuk
Kortuk
9:04 PM
@jpc, He is asking about Stack overflows on our site, it really seems that it would be the cleanest fit for SO.
 
Kellenjb
Kellenjb
@kortuk about the sinewave question, i saw a comment somewhere in the pdf about how he is able to remove the lower harmonics. I would assume this would mean that a low pass filter wouldnt have to be as good in order to get the same results
 
Kortuk
Kortuk
@jpc Well, I hope you keep coming around, I am happy to see technical members return. Also, I have no personal life, why do you need one.
@Kellenjb I would worry about higher order harmonics, he is talking about high power so the low pass filter is going to be LC.
@Kellenjb I read it, he is avoiding lower order harmonics by using a very high speed.
 
jpc
jpc
@Kortuk I would rather say he is using very high time resolution. High speed seems to imply high switching speed and this is not the case here (these sequences have very low transition counts).
 
W5VO
W5VO
Easiest way to not have a stack overflow is to have no stack :)
 
jpc
jpc
@Kortuk I guess I will have to build a small-signal version on a Cortex-M3's SPI and see what happens after RC or LC filtering.
 
Kellenjb
Kellenjb
9:15 PM
@Kortuk I could use a bagel, want to bring me one ;-)
 
Kortuk
Kortuk
@jpc That sounds great.
@jpc Yes, but he is running the algorithm at orders of magnitude greater than the sine wave.
 
jpc
jpc
@Kortuk But whose answer will I choose then? :)
 
Kellenjb
Kellenjb
1
Q: What hardware or software solutions can be used to prevent of stack overflows?

Farnazwhat is the Hardware solution For prevention of stack overflow? For example when we want to design a new operating system,how can we prevention of the stack overflow? Thank you

hardware
that question now has an answer that links to SO... maybe it should move to SO also
 
jpc
jpc
@Kortuk But it is still a lower frequency than you would run a PWM to get similar performance. And with less switching events (which are a big loss source in MOSFETs and even more in IGBTs).
 
Kellenjb
Kellenjb
@jpc it almost reminds me of dithering in that dithering is designed to have some average value created from binary, but instead of just doing a fixed number of ons/offs it is mixed up some. But in this case is mixed up in such a way to try to remove some harmonics
 
jpc
jpc
9:32 PM
@Kellenjb yeah, especially when you notice that he has two variations: for minimal transitions and for minimal THD.
 
jpc
jpc
9:43 PM
@Kortuk Are you expecting the interwinding capacitance of the choke to interfere with filtering high frequency harmonics?
Btw. How do you quote whole questions and answers here? I can't find any buttons for this. Are there some permalink based heuristics going on?
 
Kellenjb
Kellenjb
@jpc if you copy the question link and put it in the chat as a message by itself it will post the question, im not sure about the answer part
 
W5VO
W5VO
@Kellenjb If you click on the "link" button for the answer, you can copy the address. That will work with chat.
 
Kellenjb
Kellenjb
ah. makes sense
 
W5VO
W5VO
1
A: What hardware or software solutions can be used to prevent of stack overflows?

pmodYou may be surprised, but one of the options is stackless hardware architecture (either real or emulated) (discussed here). Apparently, no stack - no stack overflows.

Don't know what you were shooting for, but that's an example.
 
jpc
jpc
10:05 PM
@Kellenjb Thanks. @W5VO Nothing in particular, I was just curious.
 
James Dyson
James Dyson
10:40 PM
Hello Guys...Just wondering where I could get a good tilt/pan bracket. I have looked at many online stores but either they are too big or too small..my application is a yagi antenna aimer :)...thanks
 
James Dyson
James Dyson
10:54 PM
 
James Dyson
James Dyson
11:10 PM
Hello
 
msutherl
msutherl
11:49 PM
In the haus! haven't seen this feature yet. Does it get used?
 
Wallacoloo
Wallacoloo
What, the chat?
 
Feeds
Feeds
How to measure component distances in EAGLE PCB http://ur.ly/H2W7 #eagle
Tweeted by StackElectronix on March 22, 2011 at 11:49 PM
 
Kortuk
Kortuk
@JamesDyson YagiUda array for the win.
@jpc if you link to an answer or question and that is all that is in your message it will make it big and shiny.
@jpc Just saw that they answered it.
@msutherl .Yes, the chat is quite regularly used. It is a great way to yell at mods.
@jpc On high power signals, like a class D amplifier, you would lose alot of power on the RC circuit, so they use an LC low pass. This is not an ideal lowpass and really is a bandpass, It also allows harmonics through easier then an RC would, but it gets the job done and theoretically be 100% efficient.
 

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