Hi. This is the next video in a series of videos on LCD Technology and Design in in this particular case, designing a custom LCD display. In previous videos here, we've looked at just LCD technology overview in general and how to drive different types of LCDs so they'll be linked in at the end of this video and down below if you haven't seen that. but today, we're going to have a look at what it takes to design effectively your own custom LCD Like this.

In this particular case, this is for the new micro supply. Yes, we are working on it again and we're going to design our own custom. LCD Won't necessarily go into the reasons why it's just because we can and we like it. It's good enough reason, And it's cheap.

So there's various reasons why you might want to design your own LCD and rather than use an off-the-shelf one like a dot-matrix LCD or a dual line character-based display or something like that. So in this case, we're going to design a fairly complex LCD Like this. by complex I mean it's actually got a lot of segments in there. And basically, as we'll come to see, the number of rows and segments dictates not only how complex the LCD is, but how complex the LCD driver is as well.

So let's take a look at it now. I'm kind of actually jumping the gun on this video because I don't actually have an LCD to show you. We haven't actually had this one manufactured yet. So this video is more about what it, what is involved in just specifying up an LCD and then choosing a manufacturer and fingers crossed.

In the end, it's going to work and we'll show you that in a future video now. I'm not actually gonna recommend a particular LCD manufacturer in this case I may not even say who we're get actually going to get ours manufactured with it doesn't really matter, they're just dime-a-dozen I mean just go into Google and type in custom LCD manufacturer and you'll find like a ton of them. and if you go into say Alibaba and just you know custom LCD something like that I'm sure you'll find here we go Custom LCD Manufacturers You go online, talk to them, and they'll basically give you a quote on the spot if you've got all the relevant information available, the size, the number of segments, and what type you want and things like that. So like.

It's just no shortage of choices and like from one of the first ones on Google here. I Don't recommend them but this is some will. One popped up and they do all sorts of different custom sites we've got Co G they do o LEDs they do a character-based ones and dot matrix. find all sorts of custom, almost anything you need for a custom LCD Tell us the price son.

Alright, um, this is by far not the lowest start price you could get. We've talked to several manufacturers they're all in China and basically we chose one of the cheapest ones that our spidey-sense told us that wouldn't you know that could do the job for a some of them just you know, don't communicate properly often English Language barrier and things like that can be a problem, but sometimes like they're you know if ones are asking the wrong question, do it. You know you might just ditch them. So this price.

We just have a one-off a single price here that just came from a manufacturer that we were looking at and these were the basic aspects that we told them we need: a positive reflective display, the power supply, the duty cycle, the bias frequency that we're going to. we'll have a look at that in a minute, the viewing angle you know, standard sort of temperature range, what type we want a pin connection method in this case. although we've got the others down here and just a regular black and white with that naught point, one millimeters clearance and minimum track width and we'll talk about that shortly. And basically look here we go: A unit price in U.s.

dollars. What was this quantity for David thousand Quantity: I Thought it might be thousands. usually like a nice ballpark figure and it's not breaking the bank. Really here it is.

So for a regular pin based one which is the one that we which we're going to get manufactured we're going to get one like just your regular else. Edit: Custom LCD Glass like this with the pins on the side there. and of course you don't have to have the pins. You can remove the pins and then you can use the zebra strips as we're talked about in a previous video and that I you might save a shave a few cents off the cost there if you don't have the pins on there.

but it's basically the same glass for the pin. So a dollar forty seven in thousand quantity and then it's actually a bit of a jump. It's not usually this much of a jump, but in our case, this is what we were quoted. Two dollars 36 for the FPC or the flat flex connector version.

That's a bit strange because it's just basically conductive gluing a flat flex on to the glass as opposed to putting the pins on. so that was a fair jump to go to that flat flex. And then Co G is the chip on glass which has the LCD driver built onto it and we could have went for that. But look at the price difference.

A dollar three dollars seventy one each in quantity versus a dollar forty seven. And as we'll see, we'll take a look at the driver chip work that we're actually going to use and the price just doesn't justify using Co G but it may for your particular purpose depends on the manufacturer. If you don't have space on your PCB to lay to put you drive a chip for example, especially if you've got a lot of segments like we've got on this custom LCD That could be a real driving price. Now the tooling cost, which is a one-off non non-recurring NRI They call it a non-recurring engineering charge or tooling cost $230 It's not a big deal or so, really.

What's that? You know? A thousand under two grand for a thousand LCDs including the tooling cost and from this particular manufacturer, the turnaround time was two to four weeks or something like that. You probably could get like samples quicker if you needed to. And the flat flex one not much more. tooling cost 285, but it was a big job up to the chip on glass one, which was thirteen hundred and eighty-five So you know if you try.

If you're only making a thousand widgets and you have to amortize that tooling cost over a thousand units for example, then that's an extra dollar 38 per unit. Bomb costs you've got to amortize over so that you know that could be fairly substantial. Of course, if you're only making a hundred of something custom LCD it might be. It might be worth it because it's the only way you can get your product designed like the custom LCD makes your product.

In that case, you've got no choice, but generally you know your tooling cost might actually eat away at you in small issue volumes. Ok, so you've decided you want a custom LCD because it's going to make your product look more professional, gives you something that you can't get with a dot matrix LCD gives you a better viewing angle, very better contrast or whatever, or you're simply trying to save costs, which is often a dominant reason and why you know a one dollar watch or something? you're buying a little farting novelty gadget and it's got a custom LCD in there because in volume, they you know their cents each. Really, you know, especially if you're making a hundred thousand widgets or whatever. So cost is often a big driver, but anyway, you've decided to do that.

and if the first thing you need to do is know how many segments you've got. and in our particular case, this is the drawing which we'll go through shortly. But basically we have two hundred and twelve segments on this thing because we have to four to five displays of four digits each with the seven digits each. plus you got the decimal points.

plus we've got a bar graph, everything else, some miscellaneous annunciators, and all that sort of stuff. So 212 segments is actually a lot. So we're basically going to have to look for a driver chip which has a basically 256 segments, but as we've seen in a previous video, that you have to separate them into common drivers. So in this particular case we basically need a chip which has eight common pins as they're known and we have a pin table here to be filled in by the manufacturer as we'll explain, which has, because we've got 40 pins, we just decided to have 40 pins there because that's enough to do all of the segment's we want in an eight common by two configurations.

So we need to choose a driver chip which has eight comments and 32 segments at least. So that works out to a lot of pins. And this is why you might want to go to a Co G display chip on glass because it has the driver chip built on so you can simply talk to it via an I squared C bus or an SPI bus or whatever or the regular you know Hitoshi interface LCD driver whatever you choose to in this particular case. No, because we've just got the pins or the flat flex all the zebra strips.

We have to drive every one of these 40 pins so that becomes a problem. Now if your course, if you've got a relatively small LCD you can use your existing micro controller that you already plan to use. or you can choose a variant of the micro controller that has a built in LCD driver and a lot of them do. I Used it in my 121 GW multimeter for example I chose a particular St 32 process in which had a built-in LCD driver that had the number of rows and columns that we needed.

Now if we go over here and have a look at, say the Arm Stm32 ultra-low Power MCU line which we happen to be using and also we use this in the 121 GW multimeter as well. We chose a particular variant with the built-in LCD control of that had enough pins and you can And what I've done here is, I've sorted the parametric table here. You'll hear this sum term a lot. Parametric Table: And if you don't know what that is, it just means having all these different parameters.

hence why it's called parametric Table of the Chip. You know you've got supply volume in Max supply current and you can put operating frequency, ad converters and in this case we can actually have whether or not it's got a display controller. So I've sorted by the display controller here and you have to be careful because sometimes these aren't particularly accurate these parametric searches. So look, if you just look at this first page here, you might think that these STM are micros I Think that's one we're using the L1 five-to-one we're using on the 121.

GW Anyway, it's got like four by sixteen four comments. That's what it means for comments by 16 segments. But hey, let's just go scroll through a couple of pages. ha.

8 by 28. that one there would actually do it. So let's have a look at the next page. Here we go.

It's got 4 Commons / 31 or 8 by 28 and actually 8 by 28 would do it. That would do the 121 pins that we actually need. But the problem with this is is that it may force you into a much more expensive microcontroller because it's got 512 K of memory. or it's got.

You Know this and that it's in a bigger package, it's got more pins and it could double the cost of each appear. micro might be a dollar 50 for example, the one you were looking at using. and then when you search for one that has the built-in LCD as well, bigger package. whatever.

it might force you into another model, but it could double the price to 3 dollars for example. So you're effectively paying in that example a dollar 50 for the LCD controller and we could actually find one that actually did the job for us. here. Any one of these 8 by 28 ones would actually do the business.

and probably if you went in and see the datasheet, you could choose a different package size to get that perhaps. and it's the same across any. or you know, a lot of these microcontroller manufacturers similar sort of a story. same story effectively across them.

but you know, a dollar 50 extra for example? Or it could be 50 cents? whatever. But if you can get a separate LCD controller for less than that, then your head on your bond cost. You're you know you're winning. And of course, having a separate LCD controller chip can also have advantages in that you can physically place the chip somewhere else on the board like actually under your LCD itself.

so you get a nice routing of your pins and everything you know a fan out quite nicely to the pins of your LCD for example, whereas if with your micro, you might need that somewhere else on your board and then route in the neuro. CD might be up here and your micro needs to be down here for other reasons. You know it's got the ADC building that you're using and you want and you've got to get all these LCD lines right across the PCB can be a pain in the butt. so often decisions like that may drive you to use a separate LCD controller like we've got here.

in our case, it was just cheaper to get an external LCD controller than to use one built into the micro that we wanted to get so we can go over to Digi-key We can search for our LCD or mouse or whoever your favorite parametric provider is and allows you to like. You know, search by columns and all the different characteristics and stuff like that so we can I've already drilled down to regular segments. we'll look, we can go down. We need like at least 215 segments.

so we need at least those 600 segments. That's huge so we can apply the filter and have a look at the chips available and they're going to be really reasonably large pin count LCDs Now LCD Drivers Now here's one from Mxp, for example the PCF 8545 that's an Old Phillips thing I think old Phyllis part number you know 80 and I've sorted by price here. so lowest one first so it looks like the last one that might do the job. Eighty by four? No, that's not going to do it ad by, you know, eighty seven cents a dollar Forty getting a bit pricey, but I happen to know that I they don't sell them on digi-key but let's go over and see the display controller, which we have actually chosen.

It's actually a Whole Tech and Whole Tech manufacturer little sheep like 805 1 compatible micros and things like that you know that you'll often find in fairly novelty toys and stuff like that. And they also do a range of LCD controllers here. and we're actually going to use the HT 16 22 here. and it happens to have 8 comms and 32 segments and that's perfect for our eight common display here.

And the other thing about this Whole Tech LCD driver is that it's quite a reasonably priced. I Think we've got some quotes somewhere like Aliexpress you know you've got a wheel and deal with people on Aliexpress but you know it could be as little as 10 cents in lowish volume. So we you know we shouldn't shouldn't pay. you know, a huge amount.

So as you saw before with the the cost breakdown of this thing the Co G thing at 3.7 in one apiece compared to a dollar 47 here, then you know that it's easily paid for this chip 20 and 40 cents. It was pretty cheap. So you know, considering that our LCD only costs, you know a dollar 47 in quantity once we've amortized that $230 cost. but that's not a big deal.

You know it comes in under two dollars for that LCD solution. and I know a lot of people might say well I can go on eBay and I can get a you know, wear one of those old Nokia phone LCD things for a couple of bucks. Well good Anya If that suits your project fine, do that. you know in more power to you.

but if you want, there's very good reasons why you might want to design a custom LCD As I said, the look and feel and all that sort of thing, the view angle, the contrast, all that sort of stuff and really in volume it can get cheaper I mean this is not a particularly cheap quote we could have got. We can almost certainly get cheaper than this quote if we shop around. Alright, so we're going to need to know several things in order to provide this information of the manufacturer so they can give a proper quote on our custom LCD So in this particular case, we've got like a quarter this. The chip that we're actually using uses quarter bias, eighth duty cycle, and the refresh rate or frame frequency of 64 Hertz here.

So then we can translate that back over to our manufacturing drawing and this is where your manufacturing drawing comes in. We've kind of gone to town a little bit on this one so you don't have to get as fancy pantsy as what we've done here. I'm using Inkscape here David did this one I Didn't draw this up because my Inkscape skills are non-existent but he basically went in and drew a vector-based graphics for all of these are character displays here and we've got a manufacturing table. It's similar to when you get a PC be manufactured.

Very very similar. And I've done videos on this about actually providing manufacturing information in the Gerber files and this is a similar thing. What's going on here in our PDF manufacturing document? Here we're given: we've got our display area here 50 by 50 for our physical area. so the display area is actually the glass area that they need to manufacture.

The physical area allows for pins or whatnot and we're saying we can make the length that is modifiable by the manufacturer. If they want. You know things like that, just give them. If you give them real hard constraints, then they may actually pad the quote up because they don't have the flexibility to do whatever they want.

It might be harder for them, so just be aware of that. It gives them as much flexibility as you can. But we're We're saying a nominal power supply of three point three, We're saying the duty cycle, the 1/8 the bias of 1/4 which I've covered in a previous video, and the frequency 54 Hertz and the viewing angle. Now this is an interesting thing.

this 6, 0, 0 bottom. This is actually kind of confusing, but it's kind of an industry standard kind of thing. Let's have a look at this. This is a hand Tronics.

Our explanation of the LCD angle and basically what it comes down to is are you going to? here's your product. Are you going to look at your LCD from the bottom? So if it's lying on a table like a calculator like this, you're looking from the bottom. So we would choose the six, the six o'clock bottom position. And they work in terms of time on a clock, so that's just how they do it so that you would specify that you basically want your optimum viewing angle in the lower like looking from the bottom.

But if you're designing a rack mount thing that's sitting low or something like that, or you know you're installing it where some way a person might have to walk a by and look down on the LCD for example, then you would specify the 12 o'clock top position. so we're just specifying because our particular one, we're going to be looking from that angle. Now you can actually adjust this of course, using the contrast. so if you have it set to the center, you can actually use the contrast to adjust either way.

And you've no doubt seen that on products that have adjustable viewing angles. You can actually adjust them above and below the plane. but you want to specify if you know you're going to use it in particular orientation specify in our particular case, the bottom orientation there. So that's what we've specified there and the cooperation temperature range is pretty basic and connection method we've got FPC ribbon we don't want that David We have to fix our drawing.

We want pin I don't think this is the final one anyway and optional including quote the Co G So there's just some information there for the manufacturers so they haven't in a document. You can provide this in the email or the chat with them or whatever, but you know it's just nice to have a document like that. And we've actually specified a pin here and we've got a rough pin dimensions, but just leave it up to the manufacturer. you don't have to include any fancy pantsy stuff like this.

Now we've given them a table here to fill in. We could of course specify how to specify which segment we want connected to which pin, but then it's like PCB Routing: You can't just do it willy-nilly You can't have one over here going like two segments over here and then going to opposite sides. It just screws up the routing on the glass because they basically it essentially is like a PCB layer and they manufacture of these using layers just like on PCBs and the photographic method with the conductive pars in on the actually etched onto the glass itself. Now so generally it's best to leave it up to them and you don't even have to give them in this table.

They will simply provide you with a final table. when they ship your unit. here it is. here's your pin out.

just leave it up to them to decide which ones which is connected to the wear based on their particular routing and the thing is the or. You know, if you've got a really tight LCD where the segments are right near the edges like on this particular one, then they may be very constrained. They will be very constrained in the routing that they can do to this so you may not get what you asked for in that particular routing case and it depends on whether the pins are at the top or at the bottom. That can make a heck of a difference arm or whether or not you've only got pins on one side or connecting.

you're wanting to come out one side Depending on your system design, then you know it becomes quite complicated so. but we've basically given giving them a color-coded chart here saying if you can pretty please, group them the Commons into these particular ones. So example, you know, this red one up here may be common one. And so when you go to refresh the screen, it's easier both in software and from a visual refresh point of view to have each sort of group.

In this particular case, we have this group of eight seven segment displays that former one number. It's better to have them in one common if you can, because then your LCD can update and drive that one common. but either way it's going to work. it's It's just nicer.

if we could have them grouped and we're just saying if you can do that, pretty please. Now we've actually done this in Inkscape of course and we've given that. Well, we'll be able to give them an SVG file a vector-based file. but a lot of these LCD manufacturers are very old-school just like a lot of Piece of E manufacturers are quite old school and they might want a DXF auto Cad file for example.

So you may have to convert whatever format you have into Dxf and actually give it to them. And really, you don't have to get as complicated as this. You don't have to specify it precisely and draw it on the back of a napkin if you wanted to and give them that and say, hey, make us one of these LCDs and they'll just draw it up or whatever. Like they may even.

you know, touch this up a little bit. Shuffle things here, you know, shave a little bit off in there because just remember, when you're actually getting these manufactured, this segment in here, for example, you have to actually allow enough gap in between here, not only to route that trace out to ensure that it doesn't touch the others, to actually route out that trace that conductive trace from this inner one. but then you've got to allow the clearance as well. So that's why we said before.

typical spacing and trace width might be 0.1 millimeters and point one millimeters so you know, and that total in there would have to be naught. point three millimeters if you wanted to squeeze through 0.1 millimeter conductive trace with that, and then you've got to, of course, route it out to a particular pin so you can see why. If you wanted this segment here connected over to here, they're just gonna, we can't do it. Um, you know, what are these idiots want? You know they're they're just gonna absolutely scream at that sort of thing.

And basically they might say they can't do it or they might have a process to do it or whatever. But yeah, just be aware, routing is a big issue with something like this, and of course you can't just manufacture. You know, something like you couldn't have these solid segments. For example, you have to have the gap between the particular segments.

and in this case, look, we've got an inverse one here and and you can see how that we've specified this and we'll fill this in the table before we send it away like CN that's the segment name for that whole thing so they would know that all of that content is basically the one. The Mi and N is just the one particular segment so they wouldn't do those separately. But down here. for example, with the MJ W and H they wouldn't know whether or not you wanted W on HSM segments or whether or not you wanted it is just one segment with WH.

So you have to specify that. so we're specified that as four separate things there. And of course we've got like the inverse ones here that just give a nice high contrast. And on stuff like this like you may be wondering, well how can this in the middle of the Oh for example, how can they turn on that segment? how can they you know do that? Like how do they get the trace out? Well, because it's the one seg, if you wanted to separate segments there, you might have like you're screwed but you know they would have to have a break in there and have the trace coming out.

but because it's the same, they would simply add a very thin conductive trace in there that you couldn't see and you get all that one segment like it's the same over here with this battery one. for example, the little plus and minus in there is all part of that one segment. so they just put the little conductive GG traces in there. Just leave it up to them.

They are going to modify things anyway they're gonna use because they've got their own internal tools, their own processes, everything else so you can go to town. You know, on with these sorts of data sheets, specifying everything, and they just might redo the whole thing. but at least it's clear when you explain it to them. But of course, one of the main reasons you might want to go to town and specify the document here and the one and the reason we've did it we've we've could have told them that, just told them that hey, we wanted you know, six different seven segment displays and stuff like that and then they would have just used their own font for the seven segment display.

They would have used their own font for the characters and things like that and you mean like what they choose and produce or you might not. So by actually specifying it like this, they will try and get as absolute close to possible as possible to your particular font Here it like in theory it should be exact, but there's going to be some translation from whatever file format you've got into their particular package, but you can pretty much guarantee that's going to be extremely close to what you specify. Otherwise, if you leave it up to them, you could get the seven segments that tilt over like this. They have a thin and skinny or short and fat.

Whatever it's it's nicer if you can specify it, but you don't have to. If you've just got a simple product you want to churn out, just leave it up to them, draw it on the back of a packet. and the other reason you might want to specify your own one as well. And like in this much it detail to the manufacturer is that you can swap manufacturers because they might not give you they're not gonna give you their in-house files for manufacturing this thing usually so you know it's not like you can take those files and go another house you know to get the thing manufactured.

they go out of business. You might you know what? I have multiple sources or whatever. If the more detail you put into your drawing and specifying your LCD the more Chant the better chance you have of just simply going to different manufacturers and get in pretty much close to the same LCD produce. There's going to be manufacturing differences between them in terms of you know, the liquid crystal technology and the twist and all that sort of stuff which goes into the technology of actually producing them since one might have a slightly better contrast than another one or a slight however, might have a slightly better view angle or something like that, but at least they should be pretty close.

So there you go. I hope you enjoyed that look at designing your own LCD It's not particularly hard, it depends on how much effort you want to put into it, the more if it you put into your design documentation and designing the segments and all. that actually took David quite a while to actually render those segments and design them and things like that and tweak them. It needs to be a little bit fatter here and a little bit thinner there and whatnot.

and we actually did a bit of this on the Eevblog form as well I Think we put it in the supporters section and asked for feedback and stuff like that. and of course everyone's got their own comments on what it should look and feel like, you know? But anyway, you've got to make a decision. so we're going to get this manufacturer. We haven't get it manufactured yet, so that will no doubt be another part of this video kind of soon.

As I said, it's like 2 to 4 weeks delivery time or something like that. You probably can get shorter if you really need. I you know Express samples. but just be aware that samples that they produce.

They might be able to produce your sample in a week, but it may not be exactly the same as the production version. maybe in terms of contrast, viewing angle, whatever. But hey, at least it gives you a you know, a look and feel prototype that you can physically use power up and get get your product. You know, like an early prototype of your product working for some dog and pony show you need to take it to or something anyway.

So like that video, please give it a big thumbs up. And the other videos are linked in somewhere here. Yeah, somewhere up here at the end of the video. Check it out! Don't forget to subscribe & Alesso to Jazz Eevblog Forum down below.

Catch you next time.