The "standard" motor control setup for FOC is to do the ADC measurement synchronously with the PWM, to sample the current while the low-side switch is closed. Then the flux angles and voltages are computed immediately afterwards, and the PWM duty updated for the next cycle. This all happens in the interrupt, in a very hard real-time system -- start missing interrupts and all hell breaks loose.
PWM is run as fast as you can get away with, 20 kHz minimum (human hearing). The controller spends maybe 80% of itw time in interrupt context, leaving main context for tasks that are not time-sensitive.
I wrote a tool to do this for circuit board artwork changes. It used gerbv to rasterize the vector (gerber) files, then used XOR on the pixels to make unchanged areas disappear. For such a simple tool it is quite useful.
Everyone always brings this song up. It's very clear that Cash is playing a character of a foolish and almost-repentant criminal in the song; traditional American music records were half morality plays on rogues and half religious pleas for virtue.
It is an unfair comparison to modern hip-hop, which is primarily warrior bragodoccio. Go to WorldStar if you want to see.
Perhaps not, but it's extremely telling that most popular hip-hop songs almost all contain explicit claims that the artist committed many violent felonies, loves committing them, and will commit them again, whereas people have to dig in country music for examples of the artist claiming that they themselves actually killed or hurt someone, and when they find those examples they're always obviously playing a character.
My main point is that the equivocation of Folsom Prison Blues with violent popular hip-hop today is ridiculous. If someone wants to compare it to Dance With the Devil or or The Story of OJ or Just to Get a Rep, that's fine, but that's not the context that people usually bring up FPB in. Violence and criminality in country music very rarely touches the rhapsodic and elevated status it achieves every week in popular hip-hop, and to pretend it does so often and that they're perfectly comparable is disingenuous.
Literally the only modern country I hear on the radio involves being drunk and cheating on and fighting with your woman.
Comparing certified classics of any genre from half a century ago to slop churned out today, ignoring the fact most of it will be forgotten and new classics will rise up, is weird.
Even if it were the case that all modern music is about drinking and cheating (which if is not; according to Billboard, the most recent #1 country song is about some things lasting forever, whereas the recent #1 hip-hop songs has a bridge about 'spinning the block'), getting drunk and cheating on your woman isn't anywhere near as serious as bragging about murdering your enemies and slinging hard drugs.
This ridiculous equivalence between popular country and popular hip-hop should end. The two genres are made for entirely different social classes of people for entirely different reasons. The number of popular songs unironically glorifying violence in hip-hop is much, much higher than the number of songs unironically glorifying violence in country. The original commenter was correct.
Yes, that would be a clever comparison, if that's the sort of hip-hop that's become popular internationally. How about Cash and a modern rapper that people today have actually heard of, as the original commenter is talking about? Please, go to WorldStar and grab one of the top songs and then try to equate Folsom Prison Blues with it.
As a matter of fact, I'll start. Here's "Holy Ghost" by Future, one of the most popular artists alive right now:
> Feeling like a cigarette boat, all this water on me
> I was at my big truck, my wrist up, gettin' my dick sucked
> When I switch my wrist up, switch my car, switch my bitch up
> Every time I hit her, I broke her off then dismissed her
> I been counting this paper all day, I'm getting blisters
> Roadkill, every time I pop out in a new whip
> Gettin' you wacked, niggas ain't running off with my new drip
> Rolls hit, lights hit, platinum set, overkill
And here's Cash:
> When I was just a young boy, my mama told me son
> Always be a good boy, don't ever play with guns
> But I shot a man in Reno, just to watch him die
> Now I hear that train a rollin', I hang my head and cry
Wow, so similar. You can really see how they're both speaking the same language overall and have the same effect on society and their listeners.
To be clear, I am sure that you can find nakedly self-indulgent and violent country music if you look hard for it. But you won't find it on the top of the country charts. You don't have to look hard at all to find outrageously vulgar, explicit, and criminal hip-hop. People need to stop pretending that Folsom Prison Blues holds the same place in culture that "Holy Ghost" and its ilk does because it tells the story of a man who shot someone.
LibreCAD is a fork [0] of QCAD Community Edition. It looks very similar, but it is actually a separate piece of software.
The biggest difference I see between these two is UI and the pace of development. LibreCAD is still being worked on, but the latest stable release was in 2016. Last patch for QCAD has been released four days ago.
Personally, I prefer QCAD to LibreCAD. Both are quirky to use, but QCAD is at least a little bit less quirky. If you are coming from AutoCAD, then both will be equally confusing.
[0] Maybe not literally, README file available in LibreCAD repo declares that "LibreCAD is a 2D CAD drawing tool based on the community edition of QCAD." On the other hand, Libre Arts article [1] calls it fork.
The other big difference is DWG compatibility for interop with AutoCAD. QCAD has good DWG compat, but only in the commercial version.
LibreCAD has not-great DWG support and is free. Last I remember reading about it, they were looking to get better DWG support via the LibreDWG library, but they needed to strip out and fully rewrite a bunch of old QCAD code to achieve that, due to licensing issues.
That was the era of the elecroluminescent backlight.
This technology required a high-voltage (~100V) squarewave across the mostly-capacitive EL panel. This squarewave was at audio frequencies.
The panel also happened to function as a piezo tweeter, depending on mounting.
I worked for a cell phone company at the time. I have two memories of this technology:
1. Using the prototype phone out of its case and touching the 100 V squarewave to my ear. That's some tender skin...
2. Using a primary transformer in reverse as an audio transformer, to play the lab stereo over EL panel. It turns out the panel color changes a little bit with frequency.
So why didn't pocket pcs or non-Palm PalmOS devices have the same problem? All of the Palm units in my collection have the buzz but none of the Clies do.
After about the fourteenth time I accidentally blew my timing and size budgets with double-precision softfloat routines, I learned of -Werror=double-promotion.
It’s a good article, especially in the second half where the two theories are synthesized into a narrow, compatible summary, but the clickbait title isn’t compelling and I don’t think really describes the content.
PWM is run as fast as you can get away with, 20 kHz minimum (human hearing). The controller spends maybe 80% of itw time in interrupt context, leaving main context for tasks that are not time-sensitive.