Home Automation Hangout 2021-03-28: Debugging the SuperHouse sign

[Music] uh [Music] good morning my superhuman friends i hope you are ready for a much more relaxed live stream this week it was uh kind of intense last week going through all that legislation i don't want to do that sort of thing too often but first i acknowledge the traditional owners of this land i pay my respects to their elders past and present and to aboriginal elders and peoples from other communities who may be taking part in this live stream today so okay the topic for today is james kennewell's amazing super house sign which he made with custom pcbs and hand placing i think it was something like 300 315 ws2812b leds so it's a fantastic construct contraption but first good morning to everybody that's here already right for the kickoff we got mako long flare chip my old friend from school uh austin is here andy frank lots of people oh matt matt smith is here as well so oh and also just before this started i got a another message um so oh sorry no all right um good morning it's just over midnight andreas yes just over midnight for you and in greece which i think has just gone to daylight saving time that means it is now for apostolus it is now 1am yes okay so i was i just messaged apostolos earlier and said maybe i should do some live streams in the evening which would make it morning over in that part of the world it might be a little bit less painful i don't know uh ceon does his live stream starting at dark o'clock in the morning so that it's not so bad for other parts of the world but uh yeah 10 a.m start for me for a live stream on a sunday is a nice relaxed beginning i'm actually in here yes it's as frank said it's 10 am melbourne eu is changing tonight says mako yep uh okay way to begin where to begin all right so the sign that james made let's just switch over to where are we overhead view and we should be able to see it so i've got it sitting here on my bench let's do a quick recap because it's been a while since we've looked at this and i need to get clear in my own head what the issues are and what's being tried and what we can try again so this is going to be a bit of a a collaborative debugging session and we'll see if we can find out what's going on with this sign now uh quite a while ago now james made me this amazing sign and i'm going to grab a couple more bits and pieces to show you how it all goes together so this is the frame that it goes into let's jump back to here okay so he goes into this frame so he's made up this timber frame and stained it and put this diffuser sheet in the front and the sign fits into the back of it okay i'm going to turn off the power supply so i don't make anything go boom undo this i'm going to kind of partly reassemble it just so that you can see how it all begins now which way around i don't know and i don't know that it matters all right so this is three pcbs so super is one pcb the logo is one and house is one pcb and they are attached to this timber frame and then that frame fits down face down into let's go that way no i think it's slightly asymmetrical so probably only goes one way that's it and then that fits down into that frame and the result is that the sign oh it's upside down the sign is visible through the diffuser and there is a wemos d1 mini up the end here this is the brains of it that's providing the the pattern and controlling all the leds and then there are these little voltage regulator modules you can see a few of them still stuck on the back here and there were a few others as well and the idea is that there well there was a socket just here i took some of this off while i was doing previous debugging so there's a dc jack that goes there and then what you do is you plug in a power supply which could be uh what was it i can't remember what the power supply was might have been 12 volts or something and that then feeds into all of these voltage regulators which also power the d1 mini and the voltage regulators provide power through the back of the pcb to all of those leds so the result is that the pattern on the display can be controlled by the d1 mini now it actually works really really nicely if the brightness is turned up so let's have a look at it i'll show you the deal now i've got a um as part of trying to figure out what was going on i've bypassed all of the onboard voltage regulators and i've just ganged the power cables together this is power from a lab power supply which is sitting up here so i'll connect that back onto it bring it around turn on the power supply and you can see that it illuminates now you can also see that at the moment you can't really make out the letters very clearly in the words like in super and in-house it's kind of a blur on the camera i can read it quite clearly just looking at it with my eyes but on camera it doesn't show up very well because the intensity is a bit too much and the the camera picks it up more than it needs to and also i think in combination with the diffuser that tends to make it a little bit less clear so the solution to that is to turn down the brightness now i'm gonna where can i stick this i'm just going to balance it there for now and let's go to the desktop oh fantastic we can see the ui and we can see the sign all in one go so this is the the wled software which is running on the d1 mini and controlling it now if i come along to the color wheel here and just click somewhere else let's go green so you can see the color of the sign has changed because i've clicked in that color wheel let's make it go okay yellowy orange make it go blue [Music] and you can do different patterns and all sorts of things and it's looking pretty good but this is the issue now can you see this i'm going to have to move this window a little just a little bring it in narrower alright you see this slider up in the top right there's a brightness slider if we turn the brightness up it gets brighter obviously but less distinct so what i was wanting to do to solve the problem of of the over saturation of the sensor on the camera was to bring the brightness right down so if we bring the brightness down it begins to improve you can see it's getting a little bit sharper there it might be a little bit hard to tell but then once we bring the brightness down to a certain point how far down do we have to go well you can see the effects starting to happen there and it seems to vary a little depending on the color as well the color that's displayed so what you can see is that i've turned the brightness down and now the word super is nice and clear let's go back to that front camera okay so now the word super is nice and clear house is pretty clear right up until that point somewhere around there and that's because the leds are just barely on at the moment they're turned down a long way so this is the sort of level of illumination that i need it to work at in order to make it clear on camera and then i can stick it up on the wall somewhere but this this is what is really baffling me that's what i'm trying to figure out now if we i'm going to change it to a different color what do i what do we use maybe red yeah that makes it fairly distinct the thing is that there are many many different things that could be causing this it could be software which is not very likely but it's possible it could be hardware it could be something to do with the like the obvious candidate for this is the power rails and there are no caps on these leds so normally with ws2812 b leds what you need to do is put a capacitor typically like one microfarad or something across the power rails right next to each led because the leds tend to be very noisy they've got built-in pwm drivers which means that their current consumption is very spiky they're they're chopping the input voltage in order to achieve the the control over the level of elimination so having capacitors at every led really helps with that it helps smooth out the power supply across the whole string of leds so there are no capacitors on this at all so the obvious candidate for what's causing this is something to do with power but what exactly is going on is the question and that's where we can start digging in and see what we can figure out okay so um the other thing that sort of baffles me a little bit is the position changes so even there like i'm not touching anything right now i'm not changing any settings you can see that the flickering position varies sometimes it's there sometimes it's there sometimes it's over here somewhere like it moves around so it's like there is a failure that is occurring somewhere in the communications between the leds oh and also something else i should point out for people that haven't played with these before these leds are in a long daisy chain string so the way this works is that you have one led has an input and a power supply and an output and then the output of that goes on to the input of the next one so what you do is you uh you you treat it like a long sequence or a series of dots and you send data in the start and then it sort of ripples down the line so if you have a problem like a break partway along the chain everything after that point will fail so what this looks like is some kind of a communications error that is happening around this area but the position at which it happens varies depending on the level of illumination and that is bizarre okay so let's see what suggestions people have got oh i just saw andy sent me a message what sort of diagnosis tools are you going to start with measuring voltage and current or signal a g logic analyzer on the rgb led data in data out i'm i want to stick a scope on this now part of this is going to be poking around and learning about how these leds work as well because it's not just a matter of debugging this problem which is interesting anyway one thing that i have never done is stick an oscilloscope on the data line for ws2812b leds i've used them many times i've built them into things but i've never just you know looked at the data as it goes through so let's stick a scope on it and see what happens yeah as johnny says the bizarre part is that it's only at lower power uh now let's ah okay what i really want is more is to have more of my lab instruments wired up so i can include them on the live stream unfortunately you can't see a lot of the stuff that i can see but right now okay i'm running this off a lab power supply which is reporting to me but it's pulling around well it's jumping around between about 550 milliamps and about 700 milliamps at five volts because what i've done is bypass the voltage regulators and i'm feeding just direct five volts straight in on the power rail for all of this now if i turn the brightness up let's just click halfway current consumption has gone up to well this is actually really interesting the current consumption is now 1.69 amps but it is rock solid like it's fluctuating down in the milliamp region hardly changing at all so now that the flickering has gone away the current consumption is stable to within like less than one percent there's less than one percent variation in what it's pulling but if i drop it down to this point turn the brightness down now it is jumping around between around 500 and now about 600 and 700 milliamps i just saw so it's jumping around by like thirty or forty percent so the the current consumption is lower but because these are flickering on and off it's varying dramatically from moment to moment all right yes stable because it's not flashing yeah uh all righty ready now um let me show you a few live stream back yep so austin i think jacob johnson asked a question i missed the question but i saw austin's response sorry i can't see the question uh yeah so austin said it has ground plane and vcc plane for the pcb the pcb design was shown if you live stream back peter morning uh i would have come to your thing yesterday but there's a lot of water between you and me i hope you had fun i saw some of the pictures that you posted um so [Music] let's pull this thing back out oh and the other thing is that previous debugging sessions were done with this like i've pulled this up on a live stream before but up until yesterday this was all glued together and so the only access i've had is to the back of the pcbs and none of the data lines are on the back of the pcb and in preparation for this live stream what i did was remove a whole lot of the glue and pop it out of the frame now if we lift this see if i can get it out it's a tight fit but come on maybe get it out from one end instead of from one side there we go so i'll put that frame back out of the way now that you've seen that now you can see the individual leds so yeah all of the debugging that we've done before has been purely from the back and you really can't get to anything so there are all these little buyers in here and there are power connections on the back but you can't really see anything much else data from the d1 mini goes into the start of the chain which begins somewhere up around here i can't remember which one is the very first led we could pull the schematics out again and have a look so it's from memory the the led chain sort of wanders down follows the direction of the letters and so one thing there are a couple of things we could do here for diagnosis we could isolate sections now that we've got access to the front of the pcb we can we could do things like isolate the data link that follows over from each of the pcbs to the next pcb we could inject data directly here and run this pcb in isolation without any of the rest of it and see if we can notice anything interesting i should take the wedding ring off just in case i i was just dragging my hand across the pcb and i thought that's not such a good idea now one thing that's interesting is that right now this sign is all illuminated red and i'm just looking at the preview on the screen here the camera's not really picking that up at all all you're seeing is the flashing happening over here but this is actually all illuminated it's just the uh the way the camera picks it up if i move my hand over it look you can see there's sort of like an orange color coming through between my fingers but it's only showing up where i move my hand you can see the reflection on the edge of my fingers but just looking at this directly this that whole sign is orange all across there okay so because i'm curious i want to see the data i'm just going to connect into the data line somewhere back up here like early on in the chain i want to see what ws2812b data looks like now somewhere around oh yeah now i've got a um an oscilloscope on the bend on the shelf just over my bench but you wouldn't be able to see it so that's i've been thinking about this a lot recently i really want to do more stuff live as in technical stuff live not just talking about things but you know it's fun to mess around on the bench and get gear out and see what we can learn like that and sorry my thought process derailed there for a moment and to really do that usefully i need to be able to show things like the live oscilloscope output and even multimeter and various other things like that so i've been thinking more about how i can link that up unfortunately the scope i've got doesn't have hdmi out doesn't even have vga out so i can't capture its screen and then pull it into obs so i'm doing an alternative this is a like a mobile oscilloscope this one's prime you know mainly used for things like automotive work it's battery powered but the good thing is i can just chuck it on the bench and you can see the screen through the overhead camera so maybe we can use that to see what's going on all right but first but first all right i need some connections onto this board and earlier give me desktop please i pulled up this because i can never remember the pin out on these leds all right so the little notch is at ground and then it doesn't really matter if we're measuring off data out or data in because it's the same thing kind of just links in a chain so i'm going to i'm going to try tapping into turn this upside down i'm going to try tapping into an led here somewhere it doesn't really matter where so i could use which pin so ground and vcc are opposite and oh there's a um there's a likely candidate let's head to here oh my interesting thing now that i've got this under the microscope as you can see let's zoom right in so we can see i'm going to see if i can get some better focus on here what you can see here is the artifacts of reflow soldering just move it up here trying to get you some better focus in fact let's zoom it way way in as much as this microscope will do with this particular lens combination because what you can see are all the little balls in the solder paste brightness a bit more brightness there we go so what you can see is the end result of of the solder paste so if this was hand soldered with just wire solder you wouldn't see that effect and this is interesting because i actually thought that james had hand soldered every single one of these you know with a soldering iron and wire solder but it looks like it was done with reflow and where is that i've got to try to find where the microscope is focused which led is it it's too zoomed in there where's the pointer i can't find the pointer oh there it is okay so yeah you can see around here there is all of this residue around the joint that is because the solder paste consists of lots and lots of little balls which are all in a carrier sort of solution just scraping it away a bit there see what we can see and so as it reflows in the oven sometimes the carrier can sort of well it boils away but it can also spread and smoosh out and then you end up with a bit of residue like that so yeah looks like james did this in a reflow oven yeah oh yeah brightness is way too much with that magnification reduced so i want to make a connection to which pin well basically that one that is centered on the uh get me some solder yeah the one that's centered on the um in the field of view right now so i'm just gonna put a touch of fresh solder in there and get a a wire a jumper wire what can i use i'm gonna find myself a little off cut of wire and solder that on so that i can attach the multimeter or the oscilloscope probe to it now when i'm doing things like this i wish i had some kind of audio feedback so that i could listen to you all talking but i don't okay so that should be a good place to tap off data now we need a ground connection where's the ground connection should be plenty of them where where where five volt ground oh there's one over there okay that'll do i think if they are close enough together yep this one over here will do you can't see it from there but i'll get a ground connection on for the scope okay so now we've got ground connection here we've got a data connection here i need to get some power back under there as well so i can turn this on doing this debugging live is kind of weird because i feel the need to talk continuously it's like the the old dj thing of dead air is deadly you never want there to be silence on the radio so [Music] hmm but when i'm doing this sort of diagnostic work i'm not oh yeah it's easier if i don't have to talk continuously i suppose the best thing to do is just try to try to talk through whatever process i'm going through so you can follow along and see how wrong i am scope on hand tech hello hand tech is just going to reach just i've got no idea what the settings are on the scope let's turn on the sign and start what have we got so vmax is 5 volts v min 3.43 that's kind of surprising i would have thought that a low would have been below 3.3 maybe that's a time scale related thing so volts let's increase our scale a bit so we've got two volt scale um and let's just start playing around with the which way are we going the weird thing is i can't i'm actually having trouble reading this because i've got so much glare coming off this you on screen to you this doesn't look particularly bright to me it's like looking into the sun so uh where are we going um time division where is the time division setting on this thing time 50 milliseconds okay all right we're going to go the other way 20 milliseconds we want to make it much shorter i want to see that those data pulses come on no surely we should be seeing it by now um where's trigger trigger is set way up there let's bring it down we're not seeing any variation in this so one thing i don't know is whether um i've got no i've never actually looked at the protocol either so i don't even know if it's sending any data at any time except when yeah at any time except when it changes it may be that it only ever sends data at the time that it is updating so let's go back to here and get some kind of an animation going what can we do er solid android it doesn't even matter what the animation is as long as it's something uh well yeah that'll do um so [Music] what have we got oh back to overhead so at least now we've got data flowing through the chain so let's see what we can find see if we can get some data visible no surely not how have we not seen anything on this let's just hit the auto button and see what this thing does um turn off where's channel 2 channel 2 turn it off v max this is not making any sense so we're getting v max in here of 11 something volts minimum is jumping around all over the place [Music] am i even connected to the right place what am i looking at here we've got ground there ground to there but that which should be to a data pin and i am not seeing anything useful i'm going to increase the um the time scale again this is very strange i was expecting that i was just gonna see like a series of like that time scale is way wrong it's out in the milliseconds region many milliseconds region why can't i see it all right i'm going to go for uh i'm going to get this out of the way for now and grab a different probe because i'm not sure if this is me just not knowing how to whoa not knowing how to drive the scope or what is going on so i'm gonna see if i can see some data packets appearing here oh and i can on the rigol scope gonna get the trigger settings it's all over the place come on get the trigger gotta it this is really weird it's um much less predictable and stable than i would have expected and right now this is the most boring thing in the world to be watching because it's just me twiddling knobs on a scope that you can't even see come on trigger level [Music] trigger mode is auto yes but this voltage is wandering around all over the place all right now what have we got here so two millisecond time scale and we're on 500 millivolts per division [Music] so let's see if we can get anything that's visible to you on the screen instead of just to me by switching back to this other scope and you can see where that is and [Music] let's move this down pulse per division no 500 millivolts get it back down here oh it's getting closer to no wrong way no that way come on gotta get it down onto the screen all right so it doesn't want to go any further come on all right so what you can see here i'll see if i can get the um where's the trigger level there see i'm not changing anything there and the the voltage is actually wandering up vmax 3.98 this behavior is just strange i was seeing this on the right scope as well but what you can just barely see now if i just let it sit there and wander down again i think maybe what i need to do is i'm going to change to a pattern that has all of them illuminated so what this seems to be pointing to to me is a power issue see i'm not anywhere near it at the moment and what you can see is the average voltage is now it's rising and then slowly in a moment it's going to start coming back down again so it goes down down down down down really weird aaron says you're not on a data line that would explain it that would definitely explain it and i think aaron is right that would definitely explain it so thanks aaron so we've got ground and vcc yes what we're actually looking at here is noise on the um the main power supply line and you can see it slowly wandering up and down so this is the you are absolutely right that okay power off and disconnect that disconnect that and back to here so i was so distracted talking about the um the solder artifacts on this that i stopped paying attention to what i was connecting to so what i've connected to is the pin that is diagonally opposite the um the little notch on the led and that pin is vcc so let's see if this changes everything which i sincerely hope it does okay got some data happening there get power back on there oh nice that is like that's that's a packet of data um let's bring that back in no not 10 volts and i want to reset that in fact let's just hit that auto button again and then get rid of channel 2 and volts what are we at 20 volts no we want to be at two volts of division yeah that'll do um bring that down a bit where's the trigger bring it back up to there oh here we go let's try that is yep and then if we change the time scale that's better although i'm surprised by the volts per division that i'm look at this v-max it claims to be jumping up around 30 volts but anyway okay now we're getting somewhere i think so we can actually see what looks like a data packet and [Music] let's zoom in on it a bit and you can see that it's um [Music] where are we uh oh run stop there it is where's the trigger set trigger mode to am i sticking my head in it feels like i'm sticking my head under the camera trying to see this oh well anyway what you can see there is it looks like there are a couple of different widths of pulse you can see there's there are typical narrow pulses and then there are other pulses that seem to be twice as wide that pop up occasionally so if we could we could try capturing a bunch of it but it's kind of safe recall i've only ever used this oscilloscope a few times so i'm trying to figure out how it does stuff does it capture i have no idea i don't know if this has got memory or not let's just move this across and see if we can see the whole packet move it back yeah i'm going to switch back to the other scope for a moment the one that i do actually have some idea of how to drive and see what we can capture if anything [Music] hmm anyway not the most riveting viewing i'm sorry where's my trigger there it is yeah not very useful all right i'm going to ah also something else interesting i just noticed did i change the yes i did i'm just saying random words at the moment what's going through my head and what is coming out of my mouth are kind of unrelated and not making a lot of sense now if i turn this around there are a couple of things here firstly you can probably see that the last three leds here in the chain are not working and that could be because one of these leds has failed it could be a bad connection there somewhere or it could be as simple as i miscalculated the number of leds in the when i was looking at it so this has been configured with let's see where is config led preferences 385. let's just change this to 388 and save it and see if that makes any difference has it it has i thought there was a fault with the last three leds now just um just out of curiosity so 388 let's make that 378 save it and let's see if the last few leds turn off what i've just lost my desktop capture obs just freaked out no maybe that what see this is the thing is the more i mess around with this the more confused i get because things seem to be uh all right i'm going to turn the power off turn it back on okay that's better so now we're missing the last ten one two three four five six seven eight nine ten we are missing the last ten leds good so now we know that there are 388 leds on here i'll save that and they turn back on hooray actually this is kind of interesting so if i go back to led preferences now this is what had me confused for a moment just a second ago we've got 388 leds configured so it is sending data for 388 leds now if i change that to 378 leds and save it my at first i thought those 10 leds are just going to turn off but no they don't because they are still going to keep displaying whatever the last data was that was sent to them so if i now that i've got 378 selected instead of 388 if i change to say green you can see that it's updated the first leds up until that point and i can change that to blue and those last 10 leds have not changed color because they still have power applied to them and they are just going to keep displaying whatever was the last command that they received so now if i go back into config led preferences set it to 388 and save it will then write out data for 388 and it updates the last ones so that explains why they didn't turn off when i decrease the number of leds in the config all right so that's a problem that doesn't exist i thought there was a problem with the last three leds and it was just that i had messed up so we've got 388 leds um chubby uh oh andy just said do i have a saili a logic analyzer yes i do um oh and aaron said isn't it acting stable now is brightness turned up at the moment yeah it is turned up kind of hang on what's it set to it is set to a bit over the midpoint now part of this seems to be the interaction with the diffuser so if i drop so i've got the brightness turned right down now and you can see that it's flickering in that last part um this is all illuminated blue right now which you can't even see this is so weird the way the camera does that see i put my fingers over it and you can see the blue glow between the fingers just looking at this all of this looks blue to me and this is flashing red and other colors now if i put the diffuser over this you can see it becomes much more fuzzy there it's more distinct so one the lazy option here i'm going to turn this brightness up see so on camera that level of brightness looks fine and it's quite distinct if i put the diffuser over it all of a sudden it just becomes a blur and that uh something just messed up then that is why i want to turn the brightness down to here like down like this to make the um the letters more distinct at the moment the distance between the diffuser and the leds is bigger than it should be because this is just sitting on top of it if it was down closer it wouldn't be as blurred as that but the lazy way to solve this problem is to turn up the brightness and remove the diffuser or use a diffuser that is not as not as granular now if we look at this you can see that this consists of a whole lot of dimples that are quite large i'm going to try something different and yes i know this is not really solving the problem this is just uh we're going to find a bit of paper that doesn't have something confidential written on it oh look a credit report so if i chuck that over it it acts as a diffuser to some extent not enough though needs to be a bit more um what else can i use i've got some core flute around but the problem is that's got texture in it how about just a few more sheets of paper let me see what that looks like yes i'm probably revealing stuff there i shouldn't these documents are actually related to identity theft that's a whole other story my identity has been stolen yeah it's not really very satisfying having it like that showing the dots it's okay but i think the diffuser does need to do a little bit more than than that paper does okay so so sorry so let me ah what i'm tempted to do is just try sticking a couple of capacitors down around here although there was a i don't know if that's going to be useful but there was a very interesting question on twitter last night which is what is the total capacitance of the pcbs because these are basically poured with ground plane on one side five volts on the other so that it's just two big plates and that pcb essentially is going to be a capacitor the value will be very low obviously it's a very small amount of capacitance but still there'll be something and the question was can you measure the capacitance and i don't think we'll be able to get any useful measurement out of it because the um because it's got all these leds connected across the between the positive and negative so that would if like if each of these is going to be a it's going to be like a little current sink so if i connect a multimeter across this to try to measure the capacitance it's going to read very high because of all of those leds oh and he said notice how the last 20 or so rgb leds have a slightly different intensity of red let's see that i don't notice that i wonder if that is to do with like camera angle or where i had it i can't see any it's going to change to a different color let's go for blue hmm on camera they all look the same to me to my eyes they all look the same i don't think there's variation in intensity there um uh yeah so ray rolson said last time you looked at this the powder each section was powered by a dc to dc converter it looked like all the positive connections were connected together uh yes so the that is something that is probably uh i would classify that as being slightly dodgy so these are switch mode regulators and they're essentially wired in parallel now which way around is that from that to that okay so the wires on here are the input side and then there are outputs going to different things these have these boards have a common supply and ground all the way through them and then there were multiple modules that were just feeding it in at different points on the pcb so you can see here these three modules there was another one up here and there are different power injection points along the pcb but effectively what that does is it takes all of these modules and it connects them directly in parallel with all of their ground they're output you know negative side connected together and they're output positive sides connected together with linear regulators that is generally okay with switch mode regulators it can cause them to have problems so uh that was one of the reasons that i wanted to try isolating all of these regulators and just feed power in like this so what i've got at the moment is just the positives jumping together and the negatives jumping together now one thing i'm curious to do is try supplying the data directly to this so i could take a jumper from there and take it to the data pin on here hmm is jp7 i wonder if that started out i suspect it is so that can be daisy chained further i'd have to look up the schematic to work it out uh [Music] well i need to catch up on some chat i totally ignored the chat last week and this week i should try oh james just said good luck getting that diffuser out though yeah it is well and truly truly glued in uh all right now what have i missed and [Music] sorry i'm just getting myself organized here okay awesome so andy has been feeding me things in the background and i didn't even have that window open all right so okay so there's an observation here andy said with that android pattern it's really interesting to see that the flickering only occurs when the flickering rgb leds are being updated oh um and there was also a suggestion from some call it fun which is maybe a bad pixel in the last s yeah that was actually my original thought so when i first turned it down and i saw it start flickering at the end i thought there's an led somewhere around here that is dodgy so it'll just maybe be a matter of replacing the led and it would all be fixed but the weird thing is that the position changes and that is what had that is really what's throwing me for a loop with this and making me inclined to think that it is um that it is power supply related so [Music] i'm going to just pull up the um the design files for this because the thing is that the way these rgb leds are supposed to work is that they have internal buffers so each one of them has an input and it's got a line driver on its output now i've got to find where on earth did i put the design files for this i grabbed them off james's github and stuck them somewhere i think even searching for this it's probably a lost course i'm not gonna find it [Music] come on i think it would be too boring while i sit here and dig through you know oh maybe in archive directory [Music] which in itself has hundreds of things in it oh here we go super house logo pcbs all right i'm gonna go for the house pcb and pull it up on screen in just a second all right desktop here we go so this is the house pcb and if we look at the schematic for it it is basically a chain this is classic ws2812 so we've got data in you can see signal in this is where it comes in from the d1 mini so signal in comes in here it goes into the data in on the first led which has power and ground connected and then data out which comes to the data in on the next led and [Music] okay oh there are a few dangling nets on there so what is supposed to happen the way these things work if you feed a signal into the input of this first led internally what it does is read the data and then the control chip that's inside it then drives the output so whatever comes in on this output should be a perfectly cleaned up signal so if you've got something bad happening on the input side here as long as this led can read it you'll get a nice clean output coming out on the output signal so [Music] uh so that is why i find it weird that this is moving and if we go to [Music] um so turn down brightness go back to overhead you know do i have a desktop thing here um no i don't um yes i do sorry i can turn that on all right sorry i was just messing around with obs config so that you can see the interface and you can also see the sign now andy made the comment that it was interesting to see that it was only happening when the letters were updating look you can see that it's gone through the symbol it's getting to h and now it's moving on through the word house we'll just let it run through does its weird flickering thing there gets to the end and goes back i'm not sure if that's a clue because hmm just watching that behavior so the it is flickering even as it's tailing off yeah not sure all right sorry i'm going to try to catch up on some of these these messages because there are probably a whole bunch of good suggestions for things to investigate uh yeah so that's right so that was about some call it funds comment about a bad pixel in the last s yeah so my point about the the position of the flicker changing indicates that i don't think it's one particular led that is bad now if i go to let's just pick a different thing my phone is buzzing what's going on here not related to the live stream that's okay i am so all over the place today my brain is just not engaged all right so what was i doing blends that's right okay so what is that pattern meant to be i don't know it's like it's a oh blends between two colors let's pick a different color i think what this pattern is meant to do oh so that's color one oh okay let's make color two blue color three will make it red so so what we've got is um it's a bit hard to make out but these are sort of slowly transitioning between different colors and then from around this point it is starting to flicker but you can see that the location of the flicker is changing right there now the next thing that i think i'm going to do is i'm just going to grab a couple of capacitors and solder them across here to see what happens but first i'm going to get through some of these comments uh yeah and peter says what's interesting is the flashing is a repeatable sequence happens at the same time every time and uh mako said didn't anyone else notice the disturbances and flickering are very steady on off i hadn't even thought about that so the characteristic of the uh that is an interesting observation what it looks like it's probably a little bit hard to tell on the camera because of is there it might be a rolling shutter sort of effect on the camera so it looks like the flickering is moving across it just looking at this what it looks like to me is that all of them are flickering on and off simultaneously so there that could be a bit of an optical illusion i'm not sure it's very hard to tell because it's happening so quickly but it does look to me like they are all turning on and off it's like they're doing their pattern but being modulated as in like power being turned on and off and um peter kirk i said as soon as the h on the house starts to turn off the flashing starts hmm uh let's try a let's blink rainbow let's try a different pattern there it's almost stable and then changes color yeah it seems to be just around here somewhere halfway through the h but sometimes it makes it further back and sometimes the flickering starts down here then it just started there uh mako said what board is inside an a266 yeah it's got a wemos d1 mini which is an esp8266 aaron said caps would be the way forward but that's a lot of caps needed yes it is uh andy asked if i have a celia logic analyzer yeah so that's something else that we could dig out as well and rather than the oscilloscope use a logic analyzer and i could then pull that up on the screen i think i've got this it's a while since i've used it but i think i've got the software installed on here and uh steven w said can you monitor vcc on the end section leds and look at the s words doing the same uh look at vcc on the insection leds here so that could be worth checking out as well so henrik said just put the flicker mode and look at the s word it's doing the same pattern every time at the end of the s all right flick let's try what have we got i need to find an effect that really helps us to see this um so i've got ah this is kind of an interesting observation all right so we've got right now it is in blink which means that it is switching between several different colors so green that's blue and it's back to green and then blue but you can see when it's on the blue mode the flickering almost goes away and then when it switches to green mode the flickering comes on so flickering no flickering flickering no flickering or just a tiny little bit of flickering here oh last twenty i misread that comment earlier so andy said notice how the last 20 or so rgb leds have a slightly different intensity of red i misread that comment earlier and i thought it was that the first 20 had a different um intensity of red let's go red red red red okay so this is just solid this is supposed to be solid red right now and what you can see is that it is solid red all through here and then somewhere around here go green but it's at a different point each time [Music] yep oh ray had a comment i think i've already addressed that one paper diffuser ah so andy said when you had a paper diffuser on them perhaps getting a slightly different data rate so this was different rgb led intensity was clearly visible hmm can you remove the house sign middle led plate and output jumper in and test that yeah so changing the all right uh yeah i'm i've got a few things that i want to try but i'm going to try to read through these comments first um i've got some ideas about testing different power supply uh configurations and things so uh and henrik also said can you try the arduino fast led library demo reel with the leds and test that then you can see if it flickers as well then use another arduino if you don't want to delete the settings now yeah so that was something else that i was thinking of doing i need a list of all the things i want to try and um andy said yes and the point of flickering is exactly at the point at which the rgb led value is being changed uh looks like data corruption z-ray um william giles said try the loading effect and set the intensity to something low like 10. what is loading effect i'm not very familiar with oh there it is not very familiar with wled so i've just selected loading as the effect and should i need to do anything else or is that it does it just do it when i click it so i've clicked the loading effect okay so the loading effect runs along the string leave that down there so you can see it so it's zipping along like a worm actually i think there's a worm uh pattern as well which is kind of useful for this type of debugging no what maybe oh interesting you can see some weird flickering happening just around here that color that led these leds are a slightly different color to these other ones goes around there and then up to there and you can see that this led is flickering that one is not so this is where the chain comes in it comes in there goes around ends there that is the output that goes to the next board let's see where the next one comes in there okay so that led is being influenced or is influencing what follows on from it all right i want to start disconnecting things and moving things around but i've got to read these comments all right um create a segment that just operates house and see if the flickering happens ooh yes okay create a segment uh can you scope vcc on the house board before and after adding caps um peter said take some slow-mo video on your phone oh cool and that's an interesting idea i wonder if that would work [Music] do i have any do i have slow-mo on this phone more slow motion all right let's see if i can capture anything useful in slow motion mode and then play it back and it might be possible to get something interesting out of that transferring this so you can see it it's going to be hard you're not really going to be able to see this that you can distinctly see the flickering so this is running in slo-mo mode at the moment um uh yes okay all right there are still more comments that i haven't got to but i'm going to get back to starting to hack on it so aaron's suggestion was create a segment 238 to 388 yes so this is this is throwing back to that earlier comment a moment ago add segment so we've got segment 0 goes from 0 to 388 and i don't know how the segments work in um in this but let's just add a segment so i don't know if i need to change this to be less than 388 maybe we can just disable segment zero so let's see start led and we'll go from what was aaron suggesting 238 to 388 so that's 150 leds yes now i'm going to turn off segment zero turn on segment one i've got no idea what effect that is going to have on anything but let's now do i need to power cycle it how do we use these segments segments are there any patterns that are specific to the segments down in the s section no all right now that i've changed that i'm just going to power cycle this and see what happens okay so it's come on all solid red and then what there is no more flickering uh what what is going on here all right loading ui oh the brightness is turned up let's turn the brightness back down again yeah now the flickering is back it didn't record the segment did i need to save that how all right what's going on all right i'm going to do this again add segment start from 238 to 388 yes turn that segment on turn that segment off how do i now save that segment the fact that i've changed this in here it doesn't seem to have done nothing so i'm just going to go into config and then back again and see if it's lost it no it's still there and but when i power cycled it it lost it all righty uh okay so intermittent text said just edit segment zero to a part and then segment one to a part all right let's do that i'm gonna change this instead of going to 388 because i could be screwing it up i'm going to take it to 237 237 all right so we now have segment 0 which is 0 to 237 and segment 1 which is 238 to 388 i have no idea what grouping or any of these other settings do so and what i'm changing here doesn't seem to be having any effect i've got no idea how to use segments all right let's try this is the point at which i would start reading documentation but that's not particularly interesting to watch so what i want to do is turn off segment zero and turn on segment one how do we do this hmm said that okay so intermittent text says set the tick mark on the segment you want to change color or effect for ah okay that actually makes sense i'm going to turn this one off so i'm going to set let's see if this works i'm going to bring this up to larger desktop so you can see what's going on here all right so i've got one segment 0 to 237 one segment 238 to 388 if i now set the brightness to zero it affects all of it not just segment one i'll turn the brightness up a little uh solid i want it to be off so i'm gonna set hey this is actually kind of working you can't see it i have to switch camera reviews all right so i've got the first segment selected and i've set it to zero so now what you can see is that segment is turned off and the second segment so what i'm going to do now is deselect segment 0 select segment 1 and make it say red and turn the saturation way up i think the led count may not be correct i don't think it's 2 37 because there are another four i'm going to edit that to make that 2 33 and start this one at 234 [Music] and come back to the first segment just change its settings come back to the second segment change its settings so that it writes it out now you can what you can see here is that these first four leds are not illuminating in the h section still not illuminating oh hang on this has just changed back two thirties oh it's because i didn't tic all right i've gotta click the tick to apply it maybe now it'll fix it yeah that's better okay so now the boundary is correct so led 233 is the segment [Music] now in messing around with this user interface i have totally overlooked the fact that we've already proven something which is that the flickering continues even with all the other leds turned off and according to my bench power supply it's currently pulling around an amp ish give or take let's uh try let's add another segment i have a feeling that this may have been how james had it set up in the first place with segments so i'm going to add segment 2 i've changed that to be 234 to 388 and where does the first one end let's let's just take a guess i'm going to make that 150 and i'm going to start this at 151 and i'm going to take this one back to 233 and apply that and oh it was close so i need one two three six seven eight nine ten so stop led i'm gonna make make 160 and start led 161. so just to explain what i'm doing here i'm making three segments so that the three boards each have their own segment that we can control independently and 150 160 159 i think is where that one needs to start and that one 160 nope went too far ah 161 160 sorry i'm just eyeballing it and making adjustments as i go i'll show you in just a second so i need one more in that segment so that's got to be 230 for and that's 235 is that it no there is one led maybe i'm misreading i'm misunderstanding how this config works because it looks like there's a gap between these segments i'm going to change that back to 234 and this to 233 160 161 all right so what i'm going to do is make segment 1 red and then i'm going to select c nice segment zero then segment one i'm going to make green and then segment three i'm going to make blue okay now we have control independently over the different segments but there is an interesting thing here that top led is not turned on this led is not turned on and that one seems okay so there is something going on with the transition between those two segments okay let's have a look back at this config again so we've got zero to 160 161 is 233 234 hmm yes [Music] this is slightly baffling me because i've got start led johnny's paying me to add caps yes i do want to do that oh okay gooey gotcha some call it fun said start and end must match off by one yeah that is what i was just trying to figure out because we've got that little gap at the end there so the stop led on that one should match the start led on that one but then why don't i have a gap in here okay let's just make this 161 and we'll make this one 234 and ah spacing there was a spacing number in there james is also paying me to add caps yes all right yes that solves it okay so that gui i don't like that what it should be is the number of the first and the last led in the look at this so segment zero is from 0 to 161. segment 1 is from 161 to 234 so the first led that is defined is led 0 because we start counting from 0 but then stop led is 161. so why does the final one included in that segment have the same number as the first one included in this segment so this must actually be the led after the last one that you want to control that's really dumb all right but it just seems to be the way it is so this is the end result of what we've got so far we now have control over all four of them now i'm gonna go to what have i got selected segment two and i'm gonna turn the brightness down see if we can get some flicker happening there we go now we've got some flicker happening and what i'll do now is turn this is kind of useful for debugging because it means we can isolate things so i since i'm being paid to add caps i should do that now what is the cap value that we're meant to add and doing this with surface mount caps is going to be a pain unless there are particular places where there are no unless i diagonally linked across i'm just looking for places where i could add caps using surface amount parts instead of using through hole because what i could do is grab a box of caps what have i got in here and what should i be putting on so one micro farad what is the usual thing that you put on a ws2812 let's have a look choosing a capacitor okay and james said what happens if you only inject into the house pcb yeah so messing around with that sort of thing was uh [Music] was where i was going to get to i'm trying to do things without packing it too much all right soldering iron still on yes so that is actually a reasonably simple change i can test that without too much of a hassle okay what i'm going to do is take the data output from the d1 mini and inject it straight into this which can i get to the back of that oh getting to the isolating that is going to be tricky where is the data pin [Music] coming from all right i'm going to have to do some digging around in eagle again because i think i'm going to have to cut a track i can't easily isolate the link so the data output from from this board goes to the input on this board but it happens at these little jumpers up here there's obviously a bit of jumper wire or something soldered on the other side of the pcbs but if you look at this there is wood on it and this is all glued on so i can't get easily to the back of that that is where i need to inject i think let's find out house board yes so that is where i need to inject it hang on i should be able to just cut it on the top of the oh solution is so obvious okay let's do this soldering iron is hot so we can get straight into it and we'll do a little bit of pcb surgery all right so i'm going to do it in a reversible way obviously because i want to be able to set this back to how it was get some focus get that on there and that track that you can see running vertically straight up the middle of the pcb that is the data input pin to the house board that goes to the first led so if we do a little bit of rocket surgery on this we should be able to cut this track and isolate it from the rest so now if we bring this back over here back to overhead turn power back on we've got nothing on that last board because the data is stopping right there so let's turn that back off again and the data from the d1 mini comes out of here it's pin d2 it's that yellow wire so i'm going to remove that now one of the other interesting little things about this is that the d1 mini is running at 3.3 volts and ws2812s require 5 volt logic on the input and so what technically this is running them out of spec but i'm totally ignoring that right now now a bit of wire that'll do where have i got to get it to get there and using a this is possibly going to make things worse because not only is the d1 mini driving them out of spec it's driving the input of the leds with only a 3.3 volt logic level but now it's going to be doing it over a long wire so sometimes in that situation you get away with it when it's out of spec if the the connection from the the microcontroller is directly to the led and then yeah then it works all right but if you've got a long wire a bit of resistance in it the signal can get a bit of noise on it it all gets a bit marginal then it can be a problem so where is this thing going is going to the top left pin there we go that one right there so that pin is the data in on the first led in-house okay back to here now power and we have a nice constant house but it's being driven as if it's the the first segment so i've got to switch back to wled where are we segment zero hang on see this it's lost all the segments that i defined before i don't get wled that's weird all right turning it down turning it down whoa we have zero flickering i'm going to turn it down even more well it's working with no flickering at all totally smooth all right that means it's time for a drink now um what we can do let's do something a bit strange i'm going to loop the output of that back to the input of the word super because then what we can do oh check that out see this led turned on that's because i touched look at this i'm touching the data line just with my finger and that was enough to spoof the led into thinking that it received a command of some kind all right so if we take the output now from down here feed it all the way back into the input on the first thing basically all we've done is change the order of the panels so we've made this the input point and then that as the as the second part of the chain because what i want to find out is by doing this is where they're having all of these leds illuminated is going to reintroduce power problems possibly at the moment because we're only illuminating this section we're not seeing all of the possible electrical noise that could be going on power supply is off good before i start soldering stuff onto here all right that was very considerate of james to include the data out pin on the final board because that means we can loop this all the way back up to the input there we go now power on and it's back to high brightness because wled does not seem to be able to save anything what do you have to do to make wled save its settings oh check this out oh hang on we've got some flickering we got some flickering and it is towards the end of the chain not much though you can just see some weird things happening down around this section so to recap what we've got now is the the d1 mini data is coming on this wire and going into this so this is the start of the chain now it goes through the word house the output of that loops back around comes all the way down here and it goes back into the start of the word super so the chain goes through super and then goes to the logo so the logo is now the last part of the chain which is where house previously was like the end of the word house and what you're seeing is some weird flickering sort of things going on there now that all right some observations about this this is not what i expected of a power problem because we haven't changed in any way how the power is getting to these leds it is still the the top and the bottom of the pcb connected to all of the power and ground pins on all of these leds and we're still running the same injection so what i was expecting was that if this was a power problem the flickering would still occur through these characters even though they are now earlier in the chain because the data is taking a different path but the power supply situation is exactly the same as it was before that hasn't changed at all so that is that is interesting um yeah ray said make the at the start of the data chain to see if everything after it starts to flicker yeah we could try doing that so mecco said is it a power problem on the data line could be interference on the data line possibly accentuated by lack of filter caps now before i do much else what i'm like we could reconfigure this and change it so that this is now the start or whatever what i want to try is just adding now how are we going to validate this though we need something reproducible what i was thinking of doing was just returning it to its original configuration and then adding you know just a couple of caps somewhere around this region and see if that makes any difference to the problem so yeah what the hell let's do that i've got people in the chat paying me to add caps so i should add caps okay so i'll take that off there take that off there now this is the data line coming from the the um d1 mini now even though it's kind of dodgy having it along on a long wire for convenience i'm just going to solder that onto the start of the chain then we have the break that is up here now so i'll fix that with a little bit more rocket surgery where is that get that on there we go so a little bit of scrapey scrapey and a little bit of jump ring and that track will be repaired so i'll just get rid of this very nice looking matte black solder mask tin a little bit onto there and onto there now i need myself a bit of i had a short bit of wire i must have thrown it out okay time for another little bit of wire wrap wire here we go and chop that off to make it a bit neater so now we've got a bridge going across all right so in theory now we should be back to the original configuration let's just power it up see what happens and back into wled turn down the brightness and there we go so we're back to the original behavior of things starting to flicker crazily towards the end of the chain all right where's that big box of there it is my capacitation box let's just grab something now they're not perfect for this sort of thing but i've got i think i'm gonna have to just use some electrolytics oh my god unfortunately the um they're not ideal because the esr on electrolytics is kind of high but i can't really um just bridge ceramics in here at the moment because i don't think i've got any through-hole ceramics in the right sort of format all right so time for a little bit more bodgifying turn that off and i'll try to make sure that i don't put these electrodes on backwards because they make big nasty noises when you do so i'm gonna have to pay attention to this all right so we discovered earlier that the notch at the led is ground and the opposite one is vcc so let's find an led somewhere towards the start of the it's probably a good place to do it and hmm i can see an led here where there's a joint that looks like it's not quite soldered yeah wouldn't it be funny if that turned out to be the issue the whole time not funny not funny at all so i'm making a mess of it here all right let's start by just putting a cap on one led turn on the power see what happens yeah you can just barely see it that's the end there's an electrolytic right there across one of those now obviously one electro is not gonna well it shouldn't solve this problem hang on has it solved the problem seriously i know there is still some flickering if i turn it right down but only just well after all this one electro seems to have solved the problem uh all right just to verify now i'm gonna do something a little bit dodgy here all right with this powered up oh you can see a little flicker just down towards the end there but it's it's nothing like what it was before like before i had this this was going all different colors here it was going crazy the alum the level of illumination is turned right down now and you can just occasionally see a little flicker so i bet if i added another capacitor down here somewhere towards the end of the chain that even that would go away all right i am going to cut one lead on this capacitor and we'll see what happens look at that wow now i'm just going to hold the lead closed again yeah you can see a little flicker there but that is super distinct all right i'm going to turn that off solder this little lead that i cut solder it back together in i'm seeing stars because i've been staring at these leds i've got like white spots right in the center of the if i look at things out of the corner of my eye it's fine looks like i've got spots right in the center of my my view so i have to look at things slightly sideways to be able to see them all right so i've got another capacitor here and i'm going to do the same thing again we'll find a uh we will find a likely candidate further along the chain somewhere down towards the end and um where should we attach it find one that's oh this one looks like it's had some rework done on it so i'm going to use that one as my candidate because it's already got extra little bits of solder on it all right so ground was the was that one vcc is that one so do a little bit of bendification on these leads put that one in there that one in there and then i gotta try to well i'll bend this capacitor up so it's vertical so that it's not obscuring the field of view yes and all the people that have been shouting at me right from the start put capacitors on it are going to be 100 vindicated right now that is with the elimination turned up now back into wled now quite apart from this i am still confused about this whole wled thing of why uh why it won't save the settings that i'm changing so that is turned down to a really low level of illumination now you can barely see it on camera i can see it like i can see that each of these leds is turned on oh there was a little flicker just there maybe that's because i was sticking my hands on it every now and then i'm seeing a little flicker some led changes color and then goes back to red again but that is now with two ele two capacitors on it and you can see that that seems pretty much rock solid let's try some different colors blue oh we got some flickering ah the problem is not entirely solved i i think it is solved enough that we've demonstrated that it is a power problem hmm so with some more caps in place i think we would be fine even with different um oh intermittent tech said try the pallet effect solid fps equals 4 effect fps equals 42. intermittent tech you've obviously played with wled a lot a peter kirk or suggested the cap is compensating for a bad led that may be the case now uh sorry back to intermittent tech's suggestion palette effect palette palette palette palette palette oh come on palette palette effect and then solid fps equals four effect fps equals 42. where do i put that in are there particular configs that are specific to the selected pattern like if i go into config it doesn't have anything that is specific to that pattern so i don't know where the solid fps all that sort of stuff goes in do we put that into is there like a console where we can type commands i don't know oh okay um intermittent said no need to put fps in that's just how it works internally solid gets less updates hmm yeah solid gives you the wrong impression test with an effect okay well we now have this palette effect going and it seems to be nice and smooth i'm going to turn the brightness back down again now you can see there is a little bit of flickering occasionally just there so most of the time this is all nice and smooth and then there is sorry i'm pausing here because i'm just seeing whether i can see an effect what i'm noticing is these leds down this end it's going to be very hard for you to see let's see if i can get some zoom happening zoom and now how can i isolate this so that you're not getting glare that's gonna hmm um yeah this is a this is actually a a backing for the the lca 20 lca 2021 swag badge the conference badge this clips onto the back of it it's ready printed i just happen to have it sitting there it's not bad as a diffuser it's a bit of white petg yeah i could all right anyway back to the point what i was trying to show you was if you look closely at um one of these leds like let's just pick one you can see that it is flickering and i don't mean that the pattern is changing but every now and then it turns off and then back on again and if we scroll it scroll scroll in the real world if we scroll over here look at these leds these are rock solid they are transitioning through the different colors but there is no flicker everything flickered in because i was moving it and i think it's bumping the power leads on the back but down here even when we don't have the major flicker effect we're getting little bits of artifacts of things happening well where to from here hmm put a couple more caps on and call it done that would probably work take this back out move it here and this is with um this is with a very low level of illumination now can i bend those caps i'm going to turn this um power off while i'm doing this just in case i do something like that and break it off i'm just trying to move this cap so that i can put it in a position where where it's not going to be obscuring any of the leds this is clever i'm holding a lead while i'm soldering it nice warm lead all right so that one's there try to bend this cap in such a way that i don't short its leads like i just did but i can still get it down between the leds there so these caps are now lying flat against the pcb and not obscuring anything too much so when the leds are on none of them are being blocked by the cat bodies now i could probably add another one up around here somewhere yeah maybe i'll do that this is one of those things where i'm not entirely satisfied with the characterization of the problem it all just seems a little bit weird and yeah i am pretty well convinced that it is power now but i would have liked to have seen a little bit more about what was actually going on so 5 volts i'm just going to do it through here ground connection loop that up to 5 volts that one's ground yeah that'll do there are already some handy five volt connections on this pcb like that one right there what can i push down with that'll do all right and then i'll stick another cap down towards the end i should be doing this on the back of the piece shouldn't i um which side is which so we've got ground [Music] yeah let's do it all right if i'm gonna i started bodging these on just because it was uh it was to test what was going on but if these l if these caps are going to stay here i need to put them on the back of the pcb so question is is the front or the back of the pcb ground and 5 volts which way does it go so it looks like the back of the pcb is 5 volts and the front is ground that's slightly unfortunate because it means that i can't put it onto the back of the pcb because basically there's almost nowhere that ground is available on the back of the pcb very few places if i scratch away that silk screen that's just exposing five volts oh well i'll leave the i'll leave the caps on the front and with the um the diffuser in place you won't really see them anyway i think so i'm going to put one right down here onto this led here power's off yep good no more no zappy bangs today ah what that was disgusting heat the joint apply this holder to the joint not the other way around uh ground yeah okay and that one there did i get that right around yep marked his ground so that should be right all right turn on power again no capacitors goes bloaty boom which is good and the sign is stable there i'm going to reload it turn the brightness back down seems to be stable there that that now looks absolutely totally stable to me i can't see any flickering until i added those these last two caps i can still see a little bit of flickering but it's now just totally stable so i think we can [Music] call this one solved um all right i'm going to turn that back off again because i'm going to revert this data connection back to the short bit of wire that was doing it before instead of having this long wire looping around pull that out this yellow one is the original data connection it's got a bit of a an ugly end on it connect that into d2 bring it back around power on and now we have a functional sign brightness back down nice and stable now there was one effect that uh that i saw on it i think it was called worm no wipe or chase there was some pattern in here where oh chase that could be it where there were there was a color that ran along it and that looks kind of cool so color one make it red color two green color three blue oh we're getting flickering again it is not entirely solved yeah turn it down more to accentuate it make it worse and the flickering is back it is definitely not as bad as it was before now according to see i've turned it up just a little bit more the intensity is turned up and now the flickering has gone away normally at that intensity level that flickering would have been really bad i'm going to stick it back into what i've i didn't notice the time right i'm going to turn that off i'm going to stick this back into its case and see how it looks now with that diffuser in place which way around does this go nope doesn't fit that way fits that way good all right so it's back inside its case and looking through this diffuser i i can't see those caps at all they're invisible which is great power back on and back over this way now brightness down again all right now it's just a static thing it's not running a pattern but you can see that there is no flickering on that now turn the brightness right down so this is on a very low level of brightness now i can just barely see it glowing and there is no flicker but now if we go for a pattern let's see if we can get some flicker happening oh that's blink yeah you can see as it transitions there there is definitely a power issue still alright so where does this leave us to solve this properly i think we would need to put caps all the way through it uh it's disappointing that just putting those four caps on hasn't solved at 100 but i'm not entirely surprised this is a kind of cool pattern [Music] um yeah so where was i oh yes um now if we go back into eagle for a moment and where are we pull up the schematic now the way to actually solve this problem would be to do add a part uh hello there we go okay discrete semi cap let's pick an l805 that'll do and go what have we got to connect between vdd ground oh let's just stick it up here you go doink doink doink and bdd and oh this rep this um it's gonna look terrible because of where the tracks go but this is the general idea what you do is you take a cap and you stick it and there are some dangling traces around here get rid of those dangling traces like dangling nets so that this is the general idea what you would do is stick a cap and [Music] um we'd make that like one micro farad one micro farad no i didn't link up that last one so what we do is have a cap across the supply rails of every one of those leds and then back in here but of course come on there you go now all of these are in parallel essentially these capacitors are all in parallel they're between ground and supply voltage but the important thing is to put them in close physical proximity to um i'm just gonna stick them around here doesn't really matter at this point i'm just doing this for the uh the sake of talking about how to solve this now if we rats nest that what you would do is go zoink and dude zoink bring that one through to there so what we would have is one of these little filter caps on the 5 volt rail of every led individually and if you're looking at it in the schematic the reason i don't know if you could hear that that was my stomach saying it's lunchtime [Music] james just said i'll update the file if you want to pick and place it yeah it'll be a pain doing this by hand but what you i mean on the schematic this could be represented by just putting a whole bunch of capacitors all in parallel connected between ground and five volts and having them off somewhere else but my personal preference when laying out a schematic would be to put the um to put the caps near the part that you want it near and yeah when [Music] you're just deleting stuff because i can um i'm not going to say this obviously so what was i doing i was thinking about lunch that's what i was doing uh so the idea is that these caps even though they are all in parallel like if i if i do a net highlight so say show vcc it's connected to one side of each of these caps and if i highlight ground it's connected to the other side of each of those caps so it's effectively the same thing as as if we just you know stuck some caps along here and joined all the nets together like joined them all together what am i doing there and then you made connected that to ground and connected the other side to 5 volts electrically it is exactly the same well electrically from in an idealized sort of stylized point of view that is the same but um then we can go group blink yes merge it and vcc stick pcc up here yes so now we've got ourselves some filter caps that if we went back to the pcb layout we could then just stick one next to each of these leds and it is the same but i still prefer to put these these filter caps next to the part that they are supposed to be associated with because it is all about trace length there and there and that cap is filtering that led and then that cap is filtering that led so putting them here next to the leds directly next to them is not the same as say move group as taking a bunch of these sticking them here move and just linking them all together the total capacitance is the same what they are connected to is the same but it does not have the same effect uh actually let's rats nest this what side of the board is it there there and then we could yoink link them all together not the same thing anyway i'm kind of rambling now what did i'm okay i'm gonna get back into these highlighted um things um oh yeah so ah cable tie actually i'm i'm supposed to pronounce it cobletti so from now on cable tie is kobleti so i totally agree this is a little harder but it conveys the additional info to the consumer of the schematic yeah and that is an important point i'm trying to think of where i did this just recently there was some schematic where i explicitly put a note on it saying that the oh i remember what it was and it's one i can't show you unfortunately it was a it's a commercial project for a client i had in that case i've got some motor drivers and the there are filter caps and various other things there are some some mobs and in that what i did was in the schematic i put the fill the caps right next to the motor drivers and on the schematic there was actually a text note that says um minim uh i can't remember the wording but it's something like locate caps near related driver and minimize trace length now something like that because in some situations you you'll get someone that comes along and looks at your schematic and if you just see a whole bunch of filter caps like this it may not be obvious that they need to be distributed and associated with individual parts even though logically they're all connected to the same two places mr cablettie yeah aaron asked have you tried to put power on both ends of the lights yeah it's actually um injected at multiple places there are a few different uh points on the pcb so the entire planes of the pcb the front and the back one of them is ground one of them is five volts and power is injected at multiple locations on them so the connection across the pcb is excellent [Music] oh interesting so robson made the observation to me it looks like you have a bad led on your at logo as no matter what you do it always starts leaking from the same place i would suggest replacing the led hmm yes interesting all right i'm not going to investigate that further right now but thanks for the observation now where was okay so many comments that i've missed all right so austin's creations um said i'm on the fence if it is or isn't as the design is oh this is um sorry i was reading this out of order so austin's creation said while there might still be a bad led but the design in general is missing lots of capacitors i'm on the fence if it is or isn't as the design is bad in terms of logic 3.3 volt logic and 5 volt supply along with lots of caps missing so uh okay so intermittent tech so following on from that austin's creations after the data signal goes into the first led the data signal is in the voltage that led is getting if that is five volts then data is five volts from that led on yes and i've talked about this on a previous live stream and considering that it is now well into lunchtime i'm not going to go into it in great detail now but this comes down to what i was talking about earlier with the output buffers as well so if we just look at one led in isolation in the string so we've got power coming in here this is five volts and we've got ground then we have data in and say you were driving this with a 3.3 volt logic signal the controller i see in this led hopefully will read it even though it's out of spec in this case it's reading it but then the controller ic has its own output driver that drives the data out so the data that comes out of the output pin here will be at five volts well it'll be at whatever the supply voltage is here so if you're running these at 5 volts as they should be then the data that comes out of the first led i should have used this as the example so this is 3.3 volts coming into it on the data input the data out will be 5 volts because the driver in the led will take care of that so the only place this is actually an issue is right here on this trace it is the data coming from the microcontroller at 3.3 volts going into the first led after that it's no problem so if the first led works everything will work uh yes oh aaron said i thought a d1 mini has a 5 volt in pin right it does but it runs at 3.3 volts so the esp8266 on the d1 mini runs at 3.3 volts it's got an on-board regulator and you can supply it 5 volts but it won't run at 5 volts it runs at 3.3 and then the data pin that comes from it will be 3.3 volt logic so oh yeah and um johnny bergdahl just said it doesn't actually support 3.3 volt inputs it just happens to work yeah uh so oh actually this is a quick test that i can do my keyword said okay have you measured the supply voltage at the end of the chain um before i finish this live stream which i will do in just a moment i'm going to stick the multimeter on it and measure that the voltage at different locations i am pretty sure the voltage is going to be the same everywhere but we will measure that just to verify so wow what what was i talking about brain fade um yes so let's have a quick look at this uh ws 2812b data sheet i'm pretty sure it is 0.7 times vcc so we can do the calculation now um where are we power supply input voltage v1 [Music] where's the spec on it input voltage level yeah here we go look at this so and uh i could talk about this in more detail but i'm way over time all right so vdd so that's voltage um for like the digital data or whatever dd stands for uh yeah and i know there used to be va vb vc and the reason we have vcc and vdd is back from the days of batteries and multiple uh voltage rails but let's not get into that ancient history so uh yeah vcc the naming of vcc comes from the c battery not c cell battery that's different like i see size anyway all right so ratings 3.5 to 5.3 volts is the power supply voltage so if you're running this so it technically it shouldn't run at 3.3 volts supply voltage it's running at 5 volts in this case anyway so let's look at that vdd 5 volts nominal okay input voltage level minimum 0.7 vdd so let's do the math 5 times 0.7 is 3.5 volts so according to the spec on this on this little led you need a minimum of 3.5 volts on the input to indicate a logic high and the esp8266 doesn't run at 3.5 volts it runs at 3.3 volts so technically we are slightly out of spec by driving the led now luckily ws2812bs are fairly forgiving in that respect and as you can see it's working all right um [Music] i'm kind of just meandering around at the moment i really should just wrap this up okay uh what other comments have i managed to overlook in all of this so mako said still not sure if the caps filter the noise on the data line or just help a dodgy pixel overcome its troubles pretty sure it's in the at sign yep and many people have said that there seems to be a problem in the at sign somewhere and dodgy brothers said feels a lot like a band-aid rather than solving the problem yes exactly that was what i was very badly trying to say earlier when i was feeling dissatisfied with just sticking caps on it and having it go away but not really making it measurable oh intermittent tech said stick caps on before the problem yeah had a cap in the logo johnny bergdahl suggested oh and stephen whittaker asked what value cap was that i didn't even see that i think they're 100 micro farad or were they 10 microfarad electrodes i basically just grabbed whatever i didn't even pay attention 100 microfarad 25 volt electrodes which are not the ideal thing for this because electrodes have a higher esr or equivalent series resistance and all right i'm going to do it i've got people shouting at me to add caps before the problem and in the symbol so let's do it all right so oh um apostola suggested can you lower the voltage from your power supply without creating a problem to the circuit now that is a really interesting idea all right there are a couple of aspects to this there are squirrels i could chase if you run a ws2812b led at 4.2 volts then it is within spec for its operation and if you take 4.2 so 4.2 times 0.7 it means that it only needs 2.94 volts on its input to see a logic high so if you take w2812s and you run them at 4.2 volts and connect them to an esp8266 it is within spec for the led for its power rating and it is within spec for its digital input so that's one solution is you run them at a slightly lower voltage but let us mess around with that and see how can we let's get this um all right i'm going to get this flicker happening again you can see it's just flickering lightly but i'll try to what pattern can we use [Music] breathe now that it's not doing it i want to see if the supply voltage affects the flickering in any way solid not android i might have to take it back out of its case to remove the diffuser in fact what i'm going to do is i'm going to remove a couple of those filter caps because epistles content it has some interesting implications so let's get rid of this filter cap and this one not totally removing though i'm just taking one of the pins off and then we'll see if we get any flickering effect on this we weren't at that level of illumination that's for sure because w led has dropped back to its default all right i want to try to get some flicker happening come on give me some flicker will blink rainbow do it no oh hang on i'll set a couple of different colors on blink rainbow and see if we get some flickering no it's just blinking hmm now where was the pattern oh palette that's right so pellet was the one that we were using earlier that i think we're showing the problem no i might have to disconnect those other caps as well all right i'm going to disconnect this one this is the one that's closest to the origin of the problem i think and as people have been suggesting i should be putting a cap over here somewhere all right let's turn it back on see if we can get this flickering happening again come on give me some flicker i think i'm gonna have to disconnect all of the caps okay we've band-aided the problem effectively enough that it's all working have i disconnected them all looks like come on give me some flicker there we oh i saw a flicker for a moment i'm going to set some different color options in the in the palette make that one red oh come on how is it that we were having terrible flicker earlier and now it is working and i can't reproduce it give me some flicker [Music] flicker um mounting balls just trying some different patterns that one's no good you can't even see it on the camera and it's not really a useful one anyway candle multi how is it that ah okay i think we got it yes we've got some flicker at the end hurray flicker is back all right so you can see that it's flickering in this section here i am going to turn down the voltage on my power supply so it's currently at 5.00 volts i'm going to make it 4.5 and the flicker has almost entirely stopped you can see a little bit happening through here i'm going to set it to 4.2 volts and the flicker has gone away entirely it's on it's just like a nice consistent blue and so i'm gonna change to okay v set v64 okay that's four point two four point three four point four four point five oh now there is some flicker starting four point six 4.7 8 and now you can see the flicker is a bit more consistent 4.9 5 volts well that's interesting so running it at a slightly lower voltage could also help solve this problem all right i'm going to reconnect these now before i reconnect these ones i'm going to connect one only down here somewhere inside the at symbol when i stick that other cap now where's a good spot it'll be interesting to see the effect of a single cap that is back up in this area somewhere maybe that one i need some i need one that is in a location where i can bend the cap into a position where it's all out of the way but also one where i can get to its um [Music] yeah where i can get to its ground pinned easily enough and it's 5 volt pin maybe maybe that one no i don't like that one come on how high can this be i've got to find a spot where the angles are all just right yeah i'm going to try this one okay that led there is where i'm going to try to add the cap it's a little bit awkward unfortunately get this in there you see the plastic melt very quickly no not that one i want that one and that one so which way am i going to orient this there it's kind of a shorting danger with this position ah i know what i should do before i solder this on so while we still have zero capacitors i'm going to measure the voltage at different parts of the board all right unfortunately you're not going to be able to see the multimeter i'm going to turn on power and i'm going to measure oh it's so bright where's the connection ground okay so 5 volts and ground right at that point what how is that measuring 2.7 volts what unfortunately you can't see my multimeter is that mislabeled is that a data connection okay let's try from there to there 2.7 volts dc i wonder yeah so these caps are possibly just compensating for a much more serious issue all right let's put this on so you can see what i've got here so five volts what have i got at the end of these two how can there possibly be that much voltage drop what is going on here all right i'm going to disconnect this and put that on there five volts that is this is one of those classic things like um did you turn it on i just didn't check the supply voltage right at the start okay i'm going to disconnect this i'm going to do something different i'm going to go for what leads do i have that one yes i want this one i'm going to bypass the leads that i had coming out of my power supply i'm jumping straight into the output okay where are my test probes there 5.000 volts i'm reading across that and now i'm going to connect it to this and to this and what am i reading 2.9 volts what is that as an old friend of mine used to say is that for serious so are we getting that much voltage drop in these leads between it's like a 40 centimeter long lead the lab supply is right here it's just out of field of view of the camera and i'm now measuring 2.9 volts across that hang on [Music] was it going into i'm just really confused now and i think i need to stop for lunch because the display on the lab supply was showing 5 volts hmm i said i'm going to set it to a 5 amp current limit turn it on let's see if smoke comes out no so the power supply claims that it is outputting exactly 5 volts we're now getting 4.2 volts at 3.8 amps why was i only getting like 1.7 amps out of this earlier ah the mystery continues okay i could be here for another hour two hours screwing around with this we're already heading towards the end of the third hour so i am going to stop yes are you drawing 100 amps not quite i'm going to stop oh hang on johnny gave a link to a hack what is this one control thing using a yep oh yeah that's the diode hack yep so i talked about that in in the previous live stream so this runs the uh the first led at a slightly lower voltage sorry i'll switch to desktop view for that so the first led runs at a slightly lower voltage which brings its data in within spec so this is kind of what i was talking about before and then all of the subsequent ones run at the proper voltage alrighty i'm gonna stop now mike hewett said i think it's time for lunch ah yes um yeah it could be more than 5 amps but the thing is that i've been running all of these at very low brightness like the slider has been right down near the bottom because i've got i've barely had it turned on all right dodgy brother says can't see the forest for the trees yes yeah okay i am going to um i'm gonna call it because i need lunch so thank you for coming along on this magical mystery tour it was not very well organized or structured and i tried a few things that anyway i was not really going about it in a very logical way but it's kind of fun just to poke around in these things and see what's going on i'm gonna have lunch you should too if it is time for lunch for you and i will see you next week so thanks for coming along now go and build something awesome you

Channel: SuperHouseTV

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Id: tWTjnxB6dMc

Length: 169min 34sec (10174 seconds)

Published: Sat Mar 27 2021