Hi. This is part 2 of the Powerup Display Counter Project I'll link part 1 if you haven't seen. it may not make much sense unless you're Well, it's probably a decent standalone video if you're into like low-power LCDs solutions and stuff. So I won't to recap that video, but just an update.

Not a huge amount basically. Um, no one really pointed out any alternative. 7-segment Inc ePaper displays that was suitable. You know there's there's a couple in here that we basically got down to and we could potentially get those.

but I try to contact the manufacturers. haven't really heard back from them yet. So yeah, I don't know. I'm still looking for an ePaper E-ink solution and we may have to go for a graphic solution in that particular case.

So anyway, that's still not off the table. but it did pretty much rule out in the previous video that seven segment displays while you can get them, they're not really a thing. they're all just graphic these days, so you know they're a pretty specialized thing if you want to actually get them. So what quite a few people asked for is that they wanted to know about the little sharp memory LCD that I showed.

This is an LCD but it's manufactured by Sharp and it's basically an ultra-low power dot matrix. LCDs Solution Now, this is not a 7 segment display. it's dot matrix. But that's okay, we can work with that.

So what I'm going to do and go through in this video is just looking at the options and some calculations on how long we can get an LCD solution like this sharp Memory one or a regular LCD to work from a rechargeable either Super Cap or one of those little surface mount rechargeable batteries that you can get these days. There's quite a few people said I just get a regular microcontroller and just don't do an LCD and have a coin cell battery or whatever. And Bob's your uncle. Well, Ok, well let's have a look at that solution as well.

So these are the Sharp Memory LCDs This is the one that I've actually got here. They're all dot-matrix though. There are three wire SPI interface. you can drive them with a little $0.03 per Duke Microcontroller.

Hopefully I'm gonna have a follow-up video with the Paduka Micro controller actually getting one of those up and running with a do-it-yourself programmer and also an open tool C compiler since one I've got is 29 by 6 millimeters. Perfect. And it's six micro watts. static power consumption and dynamic power consumption when you're changing stuff on the display, which we don't need to in this case.

it's just a counter that just stays static flame. But six micro watts at 3 volts. For this thing, that's only two microwaves? Here it is 3 volts supply. That's 2 micro amps.

That's the sniff of an oily rag stuff. Now, of course, the downside to these is that they're not particularly cheap. We can get them in stopped. from dedicate.

look at this 2700 in stock. No workers, but even in thousands of quantity there 8 US dollars. We're just going to assume that cost is not really an issue here now. unfortunately.

I'm The datasheet is just a link to the brochure thing, which is like it's nothing. It's got no technical details on there I don't know is in an NDA thing, you've got to contact them, presumably what's the protocol for driving this Anyway, let's just assume that we can drive this thing and it's 2 micro amps supply current. That's what we have to beat with any alternative solution. Now to give you an idea of how low to micro amps is, let's have a look at a CR 2016 watch battery.

For example, if you don't know the numbers on there, tell you what it is. The first 2 digits the 20 is 20 millimetres diameter, the next one, the 16 means it's one point six millimeters thick. so it's 20 millimetres by 1.6 or Cr2032 will be 20 millimetres by 3 point 2 millimeters thickness Double the thickness of this. So you might find that in a typical digital watch these days a capacity of a hundred milliamp hours and that's rated at 30 K their load.

So that's a hundred micro amps load typically 3 volts divided by 30 K 100 micro amps. so it's lower than that, but you know the capacity is not going to be hugely greater at any lower currents. We don't actually have any characteristic curves for ultra low currency. We might be able to find it somewhere else, but you know it's It's not quite shelf life, but it's getting there.

Say a typical digital watch. That might have, say, a three-year battery life. I Know you can get longer, but let's just say, like a little digital watch, this just ticks over the seconds. That's all it does.

You know? Designed for ultra-low power, how much current will that actually take at three years? Well, I've got my confused here. Okay, 24 year follow along at home. 24 hours in a day times 365 days in a year. Eight thousand, seven hundred and Sixty times Three is basically twenty six thousand, two hundred and eighty hours.

Divided hundred milliamp hours by that, and I'm just invert my register. There, We're looking at about 3.8 My graph says so. Basically for a three-year battery life digital watch. For one of these coin cells, you look at a double the power consumption for my grams of the sharp memory.

LCD Granted this one is under this static consumption, but really, the dynamic consumption ticking over at once per second. Say for a digital watch, it's not hugely. You know, larger than this. So it's it's.

basically it's not going to be lower. This is still probably gonna beat almost any unless you engineer it really well. Like you're getting a watch with the custom Asics and everything else. ultra-low power solution.

Any microcontroller with an LCD is going to take more than this. So let's actually just go in and have a look at some microcontrollers and confirm that because there were a lot of people out there that said hey, just roll I've done a do-it-yourself LCD Tutorial make your own LCD tutorial video linked in at the end. If you haven't seen it aware I could design a custom LCD or I could use one. We could search digi-key for a custom seven segment.

our LCD I've got some here. you can get them on digi-key It's not a problem. Oh, all right here we go out of the fifteen hundred. LCDs We want a seven segment one.

Now that fourteen segment rubbish. As much as I love 14 segment displays, so let's say we five, six or eight. Yeah, they're all. They're all pretty large on my home after a quite a small solution.

So anyway, you might be on is yeah, okay, that's a plasma. Um, that's been missed. Missed categorized there on digi-key Oops. You know you finally get errors like they occasionally.

Anyway, these are quite large, but you could potentially even roll your own LCD As I've shown in previous videos, it doesn't cost much at all. You could do it if you really wanted to do a segmented LCD or you could find an off-the-shelf solution. But even these like you know, buy and one offer these is not. It's not hugely cheap either, so what do you need for a micro controller plus LCD solution? Well, first of all, you need an ultra-low power micro controller.

There's quite a few of those on the market from many manufacturers, no worries. but you also need one that's got the LCD driver built-in in particular for a six digit display, for example. You know that's quite a large ish requirement in terms of number of segments to try, so you're looking at a bigger chip, for example. So let's actually go into one of the traditional leaders in low-power micros.

They've got an app. Note here this white paper thing: the TI MSP thought for thirty hundred nano amps are storage mode here. less than 500 nano amps in standby, less than one micro amp in RTC mode. We don't need a real-time clock here.

we're just need it to update the display cuz the display is not static. You have to be still running the core at say 30 the internal low-power clock of 32 kilohertz, for example. There's no point running it any lower than that. Really? 32 kilohertz? As ago, most micros for low-power solutions will have built in 32 kilohertz, you know, RC oscillators, so no problem.

You don't need an external crystal timing requirements, and there's no exacting timing requirements, so it's not a problem. But already we're pushing a micro amp, but just running the RTC mode anyway. I Know this is Ti and it might be a bit biased, but they're trying to do an unbiased comparison with the Pic 24 F micros over here. Okay, so storage versus our sleep mode.

Now, storage mode is just where microcontroller can retain data on the internal SRAM but it completely shuts down. the process is not running, but it can actually wake up with external interrupts and watchdog timers and other things like that. But it's basically just keeping data in SRAM at going and that's it. And you know it can get as low as a hundred nano amps over here.

the Pic is technically lower, but TOI Acclaiming! This is where you need to get into the nitty-gritty So you can't just say go into a datasheet here and take like the banner spec up the top. You know, Watchdog timer. Deep sleep Currently, you can't just take that at face value. You've got to know exactly what your requirements are.

How are you gonna wake the thing up? Does it need a? Can it wake from an internal watchdog timer? Can it wait from an external interrupting? Or you know some other thing like that? And that's what? TIR Trying to get to here. So there's lots lots of intricacies in low-power design like this. So they're claiming that their low-power mode for at a hundred nano amps. even though the Pic claims to be like 35 nano amps or with the RAM thing enabled and to store some contents, it's 80 nano amps, but with a brownout reset option it's a it actually takes more so it's 60% plus higher.

They're claiming over here with a watchdog timer. They reckon the Msp430 or 600 nano amps over here 815 anywheres. Anyway, what does all this have to do with LCD Not much because if you search this for LCD they won't tell you anything. There's no matches whatsoever.

So this is not driving an LCD but basically the drive an LCD. You've got to have the core of the processor or at least the LCD module running. Then it's got charged pumps there that have to drive the bias voltages for the LCD If you I've got there like a quarter bias LCD or or something like that like. there's a few intricacies in there I Go into Microchips I Dunno what our type ones for the ultra low power mode extreme low power and do they call it no? they don't used to call it no, no what didn't they anyway? Um, you go into the 8-bit microcontroller ones and none of them, not the 8-bit Pics low once.

none of them have LCD controllers built-in So what one? Wah-wah right there? You're basically pushed in to the 16-bit are picked 24 F family and only these higher end ones down here have LCD modules in them. look so you basically got to get while with a crypto engine and a USB and all sorts of things. and then if you go in and have a look at the minim bare minimum microchip, one liquid, this liquid LCD liquid crystal display I Can say that Controller: these are like big chips like 64 K s Rehab Not only are they expensive, but they're quite large as well I think the smallest package is like a 44 or a 64 pin. You know, take Ufp or a Qfn.

It's like man, gross overkill with this thing. It takes two micro amps guaranteed in static mode. plus you can drive it with a three cent micro controller. It's gonna be hard to beat this if cost is no object of course.

But hey, Dave there's other LCDs like this STM one the 32 L o x3 it's like a a it's got an LCD driver for by 52 8 by 48? No worries, right? But once again, it's these are like quite large. 20 K of SRAM 6 K of embedded EEPROM 32 pin is the minimum package, right? these are I Don't even have to look up the prices to know these aren't going to be hugely cheap. So you're going to the product selector here. L Qf P 48 package 32 km Flash 30 didn't like you know that's it's a significant part that has an LCD Like wow.

Like gross overkill for simply a power up counter like this. It's sacrilege. But hey, if you look at the data sheet for this okay, 400 nano amps in stop mode 16 wake up lines that's pretty good. 800 nano in stop mode, plus RTC plus 8 kilobytes of SRAM retention data backup 88 micro micro amps per megahertz in run mode.

So you'd be using like stop mode for sure. Assume that the LCD controller works in stop mode. it may not search for that. Liquid crystal display drives up to eight common terminals, 32 segments, a phase inversion to reduce power consumption, and EMI and Bingo! The LCD controller can operate in stop mode.

There you go so it can be continuously updating, and then if you wanted to change it like if you had a clock for example, in a real-time clock running, you just interrupt that like once every second and then you just update the display and then go back down into stop mode. which was what you know. 800 nano amps or something like that. So in RTCC mode? real-time clock mode, right? So you've got to go right down to the LCD controller down here.

Okay, and this is supply current and Vdp2 volts will. Let's say it's supply current at 3 volts. Bingo! We're up to three micro amps and that is going to be I Think that's in addition. look at the Asterix down here.

One LCD No with three volts internal step active Y 1/8 Judy quarter bias division of my all pixels active know LCD Connect know LCD connected So with the extra little bit of capacitance on there, it depends how like often you're updated and stuff like that like it's anyway, it's already more just this. and also it doesn't say anything about not including the residual consumption. So basically you know you're looking in the order of really not going to get out of jail under for my cram, so double the consumption of this sharp memory LCD Just to keep that solution of an LCD on a microcontroller running for this particular one here, right? and I'm back to the pic here and I'm trying to find. you know it's got deep sleep Brown out reset Delta and me carrying me like found the LCD yet and by the way, there's I.

Spoke about the low-power RC oscillator the 32 Kilohertz one before. Here's the typical figure: this is over temperature range doesn't vary a huge amount, but it could be anywhere from the min/max there. So as I said, if you know what timing accuracy, you're going to have to use that external 32768, a Kilohertz watch crystal. and but for their own application like this, no workers look at all these performance curves.

Ah, go into town low-power but uh, give me LCD Oh Pam Comparators huh? Wow How many 353 page datasheet? How many errors in it guaranteed? Aha DC Characteristics Here we go: LCD right? So that looks like a static from anywhere from point eight to three, my cramps external internal. It's once again that's just the LCD module current LCD external in turn on one third bias still to LCD right? Okay, so that's without the charge. Pop with the charge pump here. your yeah, it bumps it right up to twenty microbes.

So if you've got a complex LCD it needs all the charge pumps and stuff gonna come. A guts are there and it jumps up by almost an order of magnitude there. So, but once again, like three my crabs right? max? Okay, the typical figure might be point Eight, so it looks like the pics doing better than the STM micro in this particular case. But if you're designing for worst case parameters which you've change over temperature and and stuff, then you've got Au which gives minus 4 is plus 85 here.

that's only for the LCD So then you've got to add on the extra. The pic 24 F plus a custom LCD could do the same Couric inception as this. I'll give it that. but as I said at the start, yeah, you've got not only the cost of the custom LCD but the cost of the micro as well.

And it's a big micro because this is the smallest one we can get I don't even want to know. like the cost of that and it's not gonna be a cheap micro. not with that amount of memory. What? No, Ah damn it.

Dev kit. let's see what Grant Imahara tells us. Do they have it There You go. Five bucks like you know, for boxing.

hundred off quantity? that sort of stuff. and it's a big-ass micro like. Okay, so let's have a quick look at the TOI Msp430 about. There's nothing in the parametric search here for LCD Aha, there it is LCD there.

So you've got to select drill down into features. Select that and we can sort by price here. 95 cents. Here you go.

Sixty sixty pins. Like you know, overkill. But I got. Let let's just run with this.

48 Punjabi Here shall we? And once again, doesn't tell you anything in your high-level specs. You've basically got a drill right to the end. At first, browse over this I'm just not having any luck finding a consumption for the LCD it could be in there, but really, it's not that terrific. Okay, it might be lower costs in this if you get like a $1 LCD micro for example, and you get your custom LCD however much that cost to get made and you amortize the cost over there, there's still like a dollar each or something like that.

It could be a cheaper solution, but it's bigger. More overkill than this little job. As I said with a three cent micro, right? So let's assume that we've got either of those solutions and we're talking in the order of like two micro amps. standby consumption don't worry about when it powers up and all that sort of jazz.

If we look at the circuitry here, we've got our product circuit. Let's say it's powered from a USB power from whatever. Anyway, we have to isolate our battery that we're going to use are our Super Cup or whatever our charge storage element is. We have to separate it from the rest of this so that when you power down this, all the back circuitry in here where work.

We're not going to get any back charge, so that's why you need to put that diode in there so it stops any reverse current. We're going to assume that we're gonna get no leakage on that diet. Like a you know, a 1 in 40, 148 or something. I'll have like tens of nano amps.

It's not. You know, it's not much. It's good enough for Australia. So then the battery or the super cap is only pairing the micro or and the LCD and that's it.

Total Consumption: 2 micro amps. So I just wanted to have a look at these funking you are TV case Sarah Charged things. These are basically surface mount and batteries. 18:12 case size.

You can pick and place them with your regular pick and place machine and like, really cool. I'm not actually sure how much these things cost, but unfortunately they've only got to up to a thousand recharging cycles so you'd have to go into the details of what happens, the longevity of them after that. Anyway, it's it's BAE Basically a multi-layer ceramic capacitor. Um, you might think Okay, well it's just a capacitor.

Why is it got a thousand charging cycles? Well, basically, they're gonna have ridiculously thin tolerances in there. and basically they're Yeah, they're gonna have a finite life unlike a regular. a regular multi-layer ceramic capacitor. Which wouldn't.

This only goes to one point. Six volts. Wow. that's big enough all, Isn't it? Something like that'll be good enough to operate like a real-time clock chip that's no good to operate our sharp memory LCD over here.

which needs it just says three volts. There's actually no. Without the datasheet, we don't know what the lower limit of that is, let alone the micro. So you can, actually, um, they're stacking in serious to get their three point two volts.

beauty. That could do the business Me, but you have your capacity and well, unfortunately I think we're going to come a gutsy hundred micro amp hours. That little tiny size is not magic. Unfortunately, 100 micro amp hours at to my Krabs that's only 50 hours.

Wat wat wat wat. Not good enough. So let's actually look at some super capacitors, shall we? I'm fifteen hundred Wow They're a thing these days. When I was a boy.

Super capacitors. Geez, that was only a wet dream. Here we go like the look of those nice surface mount months from Seiko 11 millions T 3.3 volt surface mount 30,000 in stock 68 cents. That's the business tape and real packaging.

Winner Winner chicken dinner. Let's have a look. It's the thinnest and smallest chip type electric double layer capacitor. Unique ceramic packaging, superior air tightness is used as a resort.

It offers leakage resistance. Cool backup power supply. It's exactly what we're looking at. 14.6 micro amp hours Oh So that's really for short-term stuff.

Once again, what are you expecting? A package that small I don't know. Tell him he's dreaming. Okay, so they're 11 Millions 80 millions were still not there. Look these.

Antley these are getting decent sized ones. but you know, 200 milli Ferrets. We're still not there. It was only like a couple of hours discharged.

And of course you have to watch the thing with well, their batteries and with super caps as well. You have to look at the time over the minimum discharge. So what what can your product in this case, the LCD the sharp memory LCD or your microcontroller plus LCD work down to and still give you required contrast that you need to actually display your number when the power is off. We we just don't know what that minimum limit is.

It could be 2 volts. it could be two and a half. And really what I want is an SMD like a small solution I'm going for a small LCD Like this. once again, your mileage may vary bit like I'm going for an LCD something this small.

ideally I Want a tiny little source for it, right? So if you go up to a 1 Farad capacitor, that's what a 1 Farad Super Cap looks like. That's a 2 point 7 volts, That's an AV X Our job. Really Top quality. That's a 10 Farad job II And that's a 50 Farad 2 point 7 volt.

So these things are just like enormous. Alright, so let's calculate how long a Super cap will last in this case: I'll take this monster example: 50 Farad Super Cap. Okay, we'll use an online calculator. Makes it easy you can.

There's the formulas down there. if I've done a tutorial on time constant formulas. So we're looking at that 3 volts. And of course we need a minimum voltage whip that we're going to discharge to.

Let's say 2 volts our capacitor size 50 Farad's We don't worry about the ESR doesn't matter with this sort of low current and a maximum of 2 micro amps. and bingo it calculates out that we put on the confuse er can trace it. Let's round it to 7,000 hours and it might be ok from my application. but look at the size of the thing.

anything's smaller. One Farad job'. it's 50 times less. Forget it.

So super caps aren't any good at all. If you need small saw eyes and long discharge even in a tiny - my cramps, which is about as low as it gets, really can injure this slightly low, but you're not going to get an order magnitude lower really. but even then they still aren't gonna do the business. they might if you've got heaps of space available.

Okay, no workers. You can't beat battery chemistry the Cr2016 batteries over here. or love the high energy density chemistry. A hundred milliamp hours and that is to 2 volts.

Ok, so exactly the same from 3 volts to 2 volts discharge. It's a much smaller volume than this. 100 milliamp hours divided by our two micro amps. That's 50,000 hours.

No comparison between a coin cell battery and you can even use like a smaller one. I'm just using 2016 as an example. Okay, or you can get you know solar ones directly onto the board, the tabs, and and stuff like that if you are okay with the product actually being like a like single-use but in my particular case, that'd be nice if it recharged if it did it. look, this is why I'm trying to avoid a battery solution all together.

A Super cap solution all together. That's why I looked at originally the E-ink display because it takes all this out of the equation. and if we could simply get an ink display like this this size with the seven segments, you don't need any backup solution at all and does exactly what I want, which is just leave the static image on the display. There's just no contest between two solutions.

Just go Inc every time if you could get it because there's just no contest around with super Caps and batteries and and discharge curves and and and times are recharging schemes and back diode to prevent this and that night. Like come on Anyway, yeah poor old Super Caps. they just don't cut it and even these these like little cool technology of these little micro SMD batteries. they just don't cut it either, only for very short cycle times for preventing stuff when they go down and things like that.

So there you go I've waffled on enough. ready long enough, more than long enough and there you go. I Wish I could get an Inc I'm still going to look at getting Ink Solutions still working on it I Just want to do. People wanted to know about this stuff so I hope you found that interesting.

If you did, please give it a big thumbs up. As always, discuss down below. catch you next time.