#avr Logs

Dec 16 2020

05:52 AM mouseghost: hemlo
05:59 AM mouseghost: how often do you calculate things like filters etc?
06:20 AM LeoNerd: mouseghost: vague question is vague. explain more?
06:20 AM mouseghost: LeoNerd, one can deduce filter response with math -- laplace transform and some other magic
06:22 AM mouseghost: and im just not sure how much of that i should calculate myself
06:22 AM LeoNerd: Analog filter you mean?
06:22 AM mouseghost: yeah
06:22 AM LeoNerd: Hrm.. ##electronics might be a better place,. it's not a very microcontrollery sort of question I guess
06:23 AM mouseghost: hmm, well, thanks; ill ask there :eyes: hope they wont bulli me D:
07:13 AM skz81: mouseghost, I don't understand your point... If you made the math once for a given problem, unless you suspect there is some loophole in it, or you lost/can't remember the outcome, why would you do the math again ?
07:13 AM mouseghost: hmm
07:43 AM * skz81 listen to the wind blowing...
07:49 AM mouseghost: skz81, how's it blowing?
07:51 AM skz81: mouseghost, too strongly to let me get what you meant by "im just not sure how much of that i should calculate myself"
07:52 AM mouseghost: ;/
07:52 AM skz81: Seems I'll bring my ignorance into the grave...
07:53 AM mouseghost: skz81, i didnt mean anything; that question was just a very.. wiiide one
07:54 AM mouseghost: im terrible at describing things uhhhh
07:55 AM mouseghost: for example, if i want a filter that works at a certain freq., should i derive the equation, calculate everything etc, and yeah; or use some kind of tables that provide the data
07:55 AM mouseghost: but tbh after a review calculating it doesnt seem that hard...
07:57 AM mouseghost: im just a kid, so i dont know much about laplace or calculus, even
08:57 AM alx741: hello all. I'm looking to buy an oscilloscope for mainly working with digital electronics and microcontrollers, so I though I ask you guys, would you go 2ch - 200Mhz or 4ch - 100Mhz? that is my current dilemma
08:59 AM LeoNerd: I've used 3 or 4 channels of my scope many times. Mine will go up to 50MHz but honestly, the fastest MCU I have only does 20MHz. I've not noticed a limit of bandwidth
08:59 AM LeoNerd: So in that situation I'd definitely pick the 4ch 100MHz
09:17 AM alx741: LeoNerd: yeah I likely won't need 200Mhz at all, thank you!
09:23 AM cehteh_: for digital stuff you rather need a logic analyzer
09:24 AM cehteh_: otherwise i have 2ch 100mhz and sometimes i would like if it had 4ch or logic analyzer build in
09:24 AM cehteh_: 100mhz are likely enough for a lot stuff (consider in practice you can measure less than half the advertized bw)
09:25 AM cehteh_: so 200mhz would be nicer esp 4 channel scopes often have only 2 ADC's means muxing and thus you get 4x 50mhz
09:26 AM cehteh_: which might be a little low esp when you want to look at signal edges in detail, swinging/bouncing
09:46 AM rue_mohr: I found that most of the digital stuff I do, the logic ana is preferable to a scope
09:46 AM rue_mohr: "most" - some of my digital stuff borders analog
09:51 AM cehteh_: in practice all sigital signals are analog, and often enough the scope is the tool to figure out if that analog view is correct
09:52 AM cehteh_: steepness of edges, overswinging, levels, timings
09:52 AM cehteh_: when buying a scope i'd consider that the most important part
10:05 AM twnqx: i have a clck generator that prodces -2V undershoot :S i wonder if that dangerous for my ICs :(
10:38 AM cehteh_: could be, question is how much current it delivers and how long this undershoot remains
10:38 AM cehteh_: does it stay under load?
10:41 AM LeoNerd: How did you measure it? Into open circuit on just a scope probe - 1Mohm or so? Even tiny trace capacitance can make a ground bounce there
10:41 AM LeoNerd: Try adding even just a 10k resistor, and see if it still does it
10:42 AM cehteh_: yeah
10:42 AM cehteh_: often such is a measuring artifact
10:42 AM cehteh_: i wonder if its worth to get a x100 probe
10:43 AM cehteh_: prolly not, because of noise
10:49 AM twnqx: 8284 into 8088
10:50 AM twnqx: so, slightly loaded, but cmos inputs have a pretty high impedance anyway (not 8088, but cmos V20)
11:00 AM cehteh_: i wonder if that isnt disscipated on protection diodes .. but then at least it wastes energy
12:46 PM Maya-sama is now known as Miyu
01:15 PM rue_mohr: I put $1000 into a tek tds754C and I dont regret it
01:16 PM rue_mohr: I have yet to use it to test a mechanical servo
01:40 PM specing_ is now known as specing
10:18 PM vgtw_ is now known as vgtw