EEVblog 1699 - uTimer PROJECT - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: August 02, 2025, 12:31:00 am
content: Part 1 of the µTimer project, a versatile benchtop lab timer.Choosing the LCD, and getting two sample LCD's running. One using a demo board, and one that needed to be hacked onto a Raspberry Pi.00:00 - Benchtop Lab Timer Project01:19 - It's all about the choice of LCD03:14 - ERC19624-1 192x64 Transflective 4" LCD03:44 - Reflective vs Transflective LCD's05:01 - ER3806 Font Chip06:06 - Demo Board09:10 - LCD Bias Angle and Viewing Angle Explained11:45 - What is THAT? LCD Bleeding?13:19 - Power consumption measurement15:48 - Trying another LCD, the ERC19624-6. What difference does a dash number make?17:15 - Bodging on the LCD connector to the breakout board20:34 - The pin offsets and lack of routing is annoying...22:10 - Reprogramming the 8051 demo board, it should be easy, right?26:32 - Entering The Matrix29:40 - More soldering30:33 - The Programmer Software doesn't work without a HEX file...32:17 - All of that for nothing...33:40 - Let's try this Arduino / Raspberry Pi ST7525 LCD code35:36 - Getting the Raspberry Pi running and installing the BCM2835 C library38:56 - Getting the Make to work on the source code.40:01 - Make Clean should work...41:16 - Winner Winner Chicken Dinner41:10 - Power consumption measurement. This one is supposed to be much lower...42:58 - Changing the LCD contrast in software45:10 - Is it better or worse than the first LCD?46:37 - ConclusionLinks:https://www.buydisplay.com/4-inch-low-cost-white-192x64-graphic-cog-lcd-display-st7525-spihttps://www.buydisplay.com/4-inch-cog-192x64-display-graphic-lcds-module-ist3020-black-on-whitehttp://www.airspayce.com/mikem/bcm2835/Font Chip:https://www.buydisplay.com/download/manual/ER3806-1_Datasheet.pdfCustom LCD videos:https://www.youtube.com/playlist?list=PLvOlSehNtuHvmK-VGcZ33ZuATmcNB8tvH

author: Whales
author_rank: Super Contributor
timestamp: August 02, 2025, 04:12:01 am
content: Awesome vidPlease look at mounting options next (rear pressure, adhesives, etc); I'm currently having a grumpy time with some small-bezel colour LCDs, but I'm also trying to have them waterproof :| so beyond your scope.Not being able to run ./lcdtest after running make:this is the fault of unix voodoo and your USB stick having a windows (probably fat32 or exfat) filesystem. The problem was solved when you moved the files to your raspberry pi's (probably ext4) filesystem.On windows: a "program" is a file that ends in .exe, .com or similar. Double-clicking or typing the name of said program will run it.On unix-likes: a "program" is a file with an "execute permission" set for it. Files with this permission are typically displayed as green when you type lsMy example:From your vid:Fat32 can't store this special bit for each file, so no files are ever executable on fat32 filesystems (technically this isn't always true, but close enough for most users).Don't ask why it's done this way, it's lots of historical multi-user-unix-mainframe stuff combined with a fear that people will accidentally run programs by typing their names. That's likely also the reason we are forced to type "./programname" instead of just "programname" to run a program in the current folder -- what if someone put a program called "ls" on a usb stick that was a virus? Still, very annoying, especially if you're not familiar with the problem or are used to DOS.

author: EEVblog
author_rank: Unknown
timestamp: August 02, 2025, 09:54:57 am
content: Quote from: Whales on August 02, 2025, 04:12:01 amWow, thanks, so it wasn't me.I was puzzled by this, but copying the files worked so I just carried on.Not sure what prompted me to copy the files and try again though, just a hunch I guess.

author: chilternview
author_rank: Frequent Contributor
timestamp: August 02, 2025, 10:15:34 am
content: Why not colour OLED than black&white LCD? I hate theose old fashioned LCD displays.

author: Whales
author_rank: Super Contributor
timestamp: August 02, 2025, 10:27:31 am
content: OLED and monochrome LCDs are magnitudes different in terms of power consumption. Also a reflective LCD is set and forget, whilst an actively lit screen requires brightness controls (or annoyance).@3 minute mark: Dave wants this battery powered and to show a clockface on it when not in use. I suspect this is partly motivated by removing the need for power supplies and worrying about isolation (compare the annoyance of using an oscilloscope vs a handheld multimeter).

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 02, 2025, 10:29:02 am
content: If a manufacturer is offering a RasPi demo for their product, it would save so much time if they just provided a full SD card image, so no RasPi knowledge is needed.

author: chilternview
author_rank: Frequent Contributor
timestamp: August 02, 2025, 10:30:15 am
content: Quote from: Whales on August 02, 2025, 10:27:31 amFair enough. I'd rather have the higher power consumption and shorter battery life with a nice display, but I guess others may not.

author: typematrix
author_rank: Contributor
timestamp: August 02, 2025, 10:38:25 am
content: Hi ,I have a combined display Raspberry pi library which supports the ERM19264 / UC1609 controller ,I think the UC1609 is compatible with ST7525 but have not looked into it in detail , Someone at buydisplay told me ages ago according to my notes.Its called Display_Lib_RPI on github.https://github.com/gavinlyonsrepo/Display_Lib_RPIWould be interesting to know if it works.

author: iMo
author_rank: Super Contributor
timestamp: August 02, 2025, 10:42:11 am
content: What would be a practical usage of such an uTimer in the lab? Perhaps - in a chemistry lab or a similar one lab where you have to cook something for, say, 360 minutes long..In an EE lab you have to measure or watch time with picoseconds resolution these days, imho.. unless you want to measure the time you need to find and fix a shorted capacitor on a motherboard....

author: EEVblog
author_rank: Unknown
timestamp: August 02, 2025, 11:37:52 am
content: Quote from: iMo on August 02, 2025, 10:42:11 amYou're not thinking 4th dimentionally.

author: EEVblog
author_rank: Unknown
timestamp: August 02, 2025, 11:40:50 am
content: Quote from: mikeselectricstuff on August 02, 2025, 10:29:02 amI don't know why they offer that demo board, seems overly complex having to supply a different programmed MCU and I/O matrix for each display.Just have an Rpi SD card image as you said, and supply the cable with the adapter board.

author: EEVblog
author_rank: Unknown
timestamp: August 02, 2025, 11:41:52 am
content: Quote from: chilternview on August 02, 2025, 10:15:34 amOLED's are power hogs.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 02, 2025, 11:58:54 am
content: Quote from: EEVblog on August 02, 2025, 11:40:50 amIt's probably just a very old design they keep using because it's familiar - design resources in China are scarce

author: chilternview
author_rank: Frequent Contributor
timestamp: August 02, 2025, 12:33:11 pm
content: Quote from: EEVblog on August 02, 2025, 11:41:52 amCan you quantify that? As it would be good to know. My iphone has a timer/alarm/clock, in colour, so why would anyone want a standalone timer? Jast asking.

author: themadhippy
author_rank: Super Contributor
timestamp: August 02, 2025, 02:45:04 pm
content: Quotecan you plug remote triggers directly into your phone? are you willing to leave yer phone attached too the test bench for sevral hours maybe even a day or 6? how longs the battery in your phone going to last without a charge?what happens when someone calls for a private chat that means you need to leave the room? shall i go on?

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 02, 2025, 04:27:37 pm
content: There are a few OLED DMM's out there and they tend to have a very short battery life. Like 10 hours or so, and Dave is attempting to get several hundred hours. There are also quite a lot of hacks of replacing OLED displays in these DMM's because they stop working after just a few years.For the rest...When I saw the Brannan timer on Dave's desk a few months ago I thought it was a quite cute thing, and assumed it was EOL somewhere in the '80-ies or so, but apparently it's still in production, and with the external inputs it costs around EUR 50:https://www.brannan.co.uk/product/bench-top-timers-with-external-triggering-contacts/My guess is that you're not going to get a long (years) battery life out of a high resolution dot matrix LCD, and replacing batteries a few times each year is a nuisance. Running it from a rechargeable bag seems a more sensible option to me. Plugging in an USB cord every now and then on your desk is not such a problem. Popping in an 18650 reduces "charge time" to less then a minute.Ultra low power is very nice in some situations, but if it's intended to use in your lab, then size and weight are much less of a concern. Standardizing on 18650 makes the most sense to me. Take the micro Current for example. On itself an interesting project but I would not buy it. Making an 10x 100x 1000x (differential) amplifier is quite simple and makes more sense to me. Pop in two 18650 cells and you get some decent run time even out of a power hungry opamp or inamp.Also, small 1W to 5W SMPS circuits are cheap. From the DC-DC converters to "Mains to DC" blocks. Or even bog standard USB power supplies. Everybody already got plenty of those within arm's reach.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 02, 2025, 05:16:46 pm
content: For functionality and feature creep:A lab bench timer really begs for feature creep. There are already a gazillion stop watches and simple timers, and once you have a uC with a decent display on a PCB with some power, you've already got 80% of the hardware for a very capable timing device.I'm looking at the front panel of the Tektronix dc509 for inspiration right now.GHz capability is a bit excessive for a "simple desktop timer", but any decent uC can measure up to a bunch of MHz accurately and timing intervals with better then us accuracy.Another good source for inspiration are the user manuals of DIN-Rail Mount Multifunction Timer Relays. These have start , switch off and pulse functions. And of course, they have Relay outputs!I very much like some simple start / stop push buttons such as on the Brannan timer, but a more capable timer surely begs for at least one rotary encoder. Both for setting intervals, and for scrolling through menu's. (A touch screen could work to).DC509 has adjustable trigger levels. That certainly makes it more universal.I'm also looking at the W1209. It's a china express cheap thermostat with 3 char of 7-Segment LED display. 3 characters is not much for a timer, but adding thermostat functions to a timer would be very nice.Blinking a LED an/or a buzzer for when timer intervals or an alarm (temperature) has exceeded a threshold also seems a very sensible extension. When you're designing a product, keeping track of heatsink temperatures is a common task, and so is adding an ad-hoc fan for some additional cooling.Heck, I'd certainly want a decent built in ADC. 16-bit with differential inputs and a PGA (measuring up to 50V or so) would be nice, but just a 10-bit ADC present in most uC's combined with an opamp and some CMOS switches to extend the range would already be very useful.Adding a connector with a bunch of I/O pins seems very sensible. It can keep feature creep to a minimum while still allowing for extensions such as thermostats, relays, sensitive ADC front ends (for chemical experiments?) Maybe two connectors: One internal for "fixed modules", and one external for temporary or swap-able modules. (keep pinout compatible).

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 02, 2025, 05:42:00 pm
content: Hacking, Open Source (+ Hardware) + Community?If this is going to be a real life product. It's very likely go be hacked into and modified by quite a lot of people. To me it makes sense to turn this into a community project right from the start. Community projects need a project leader to give it guidance and a clearly defined scope. Dave can of course design whatever he wants. Define functionality and features etc...But if the bare hardware is capable enough, then I'm sure plenty of people would want to contribute, and more interest if the hardware can do more. If there is a software framework with menu functions, then individuals can add specialized functions to the menu. If there is some (for example I2C) ADC defined, then people can add software functions to it.I have thought long and hard of buying a 121GW, and the reason I did not was because the software had to be reverse engineered. In the end I bought an BM869s instead, as for my use, I prioritized accuracy and reliability over functions.I'm not much use for writing software these days due to concentration problems, but I can put in a bunch of hours in PCB design and layout. Give me some type numbers of an uC and some peripheral IC's and I can work out schematic details. Give me a PCB outline and connector placement and I can fill in the rest. I'll put in some hours for free, but getting a prototype for (proven) hours put into it is an extra motivator. It's not really about the money, it's more about a return of favors and community building.

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 03, 2025, 12:46:46 am
content: I think the Memory LCDs were mentioned, but possibly you rejected that because there wasn't one large enough for your project? There is. Several of us just here have used the 4" version which is 400x240 (IIRC) and has very good contrast and viewing angle. It doesn't seem to be available anymore from Sharp for some reason, but they have a bunch of new references to choose from:https://www.sharpsecd.com/#/memory-in-pixel-lcds-productI'd be surprised if you didn't find one that fits.The downside is the cost, but I don't know if it matters in your project or not.With that being said, a graphic LCD is great for flexibility, but why not consider designing your own custom LCD for this uTimer project? You've done this before, and I think it gives great results if fixed segments and symbols are fine.

author: EEVblog
author_rank: Unknown
timestamp: August 03, 2025, 11:59:02 pm
content: Quote from: SiliconWizard on August 03, 2025, 12:46:46 amYes cost matters, and so does form factor. There just isn't a suitable form factor available either.The only ones in a suitable size are square form factor and 320x240.

author: EEVblog
author_rank: Unknown
timestamp: August 04, 2025, 12:02:42 am
content: Quote from: Doctorandus_P on August 02, 2025, 05:42:00 pmNo thanks. It's a technical dictatorship or bust.

author: BrianHG
author_rank: Super Contributor
timestamp: August 04, 2025, 12:10:01 am
content: Quote from: EEVblog on August 02, 2025, 11:41:52 amMaybe e-paper / e-ink displays.Low-res monochrome wont be as cheap as LCD, around 6$-9$ USD, but very low power and excellent viewing contrast and angles.Though, for minimum power, you would need to refresh the unit seconds digit every second, then, refresh the rest of the display only as needed.

author: EEVblog
author_rank: Unknown
timestamp: August 04, 2025, 12:41:18 am
content: Quote from: BrianHG on August 04, 2025, 12:10:01 amThey are not designed for continuous and fast display updating.

author: BrianHG
author_rank: Super Contributor
timestamp: August 04, 2025, 01:23:27 am
content: Quote from: EEVblog on August 04, 2025, 12:41:18 amNo, it will not match the speed of a LCD.You can get away with the seconds digit being a little blurry until you pause the timer.You will not get 1/10th of a second to show until you pause the timer.Since I do not know what else you want to display, I cannot say anything else other than painting black pixels is OK in speed, it is the erasing back to white which is slow.The black & white ones arent too terrible in speed, it is the displays with shades of grey and multi-color which really need a lot of time to 'erase' the previous frame with multiple refresh passes to draw a new image.

author: BrianHG
author_rank: Super Contributor
timestamp: August 04, 2025, 01:26:42 am
content: Here is what the seconds would look like on a monochrome e-paper display:It is better than I thought. 1/10 of a second may also be visible.Note that his code is just erasing just the digit which is changing instead of a full paper clear command.

author: EEVblog
author_rank: Unknown
timestamp: August 04, 2025, 02:14:38 am
content: Quote from: BrianHG on August 04, 2025, 01:26:42 amIt's not just the speed, it's the lifetime endurance, they are not designed for continuous updating 24/7

author: hans
author_rank: Super Contributor
timestamp: August 04, 2025, 08:18:43 am
content: e-paper or e-ink have a limited amount of refresh cycles the screen can endure.For an e-reader, that will be fine for say 1M full screen refreshes. Thats a lot of books.1M second refreshes wont even last 2 weeks.Not sure what the actual rating of modern displays is, that 1M is a number I pulled from my arse. But I do know they are very limited.Just going to throw my self right into the 'technical dictatorship discussion':I'm fairly certain Dave already has a (better than) rough idea where he wants this project to go, otherwise he won't be looking for a suitable screen. In my own experience, getting fancy parts and then looking for the right projects to make with them is never the right way of going around things.But obviously, since this is the first video in this series, Dave hasn't told us the 'feature creep' list yetBut I"m looking forward to it! Design series are always fun to watch and think along. Just like the uCurrent and uSupply it will inevitably spark some community spinoffs

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 05, 2025, 01:17:08 am
content: Dave! You're designing the same project that I am (for personal use). How'd we do that?!

author: EEVblog
author_rank: Unknown
timestamp: August 05, 2025, 01:44:03 am
content: Quote from: ballsystemlord on August 05, 2025, 01:17:08 am

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 05, 2025, 02:19:50 pm
content: Quote from: ballsystemlord on August 05, 2025, 01:17:08 amA timer is not rocket science. The DMM Continuity checker I saw recently is also already pretty close, just needs a bit different firmware.

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 05, 2025, 02:28:08 pm
content: ePaper is expensive, it's laggy - even though the modern ones with partial update can have a decent update rate for small areas, and it actually draws a LOT more power to update than LCD. Yes they draw down to zero power when *not* updating, but for a display that constantly changes, that's not a good power deal. At all. The other downside IMO for applications when the display changes frequently is what makes them great otherwise: they retain what's on display after a power loss. So you end up with the last thing that was on the display, "permanently", which can be pretty confusing in terms of UI. Imagine, in particular, a clock that displays time & date and that displays something that's not correct and never updates. That's from annoying to possibly dangerous depending on the application. To mitigate it, you would update the eInk display on a regular (and short) basis, such as updating seconds, or otherwise making some icon "flash", or something, such that the user sees the device is operating and not just dead.They're great for tags and for eBooks (great to read), but not so much for almost anything else, IMHO.Memory LCDs are great but if Dave didn't find one that fits, that's it.I suggested a custom LCD though - as Dave didn't reply to that (or I missed it), I'm assuming he rejects the idea even more so than using memory LCDs or ePaper. It has a upfront cost and is of course a lot less flexible, but is otherwise pretty good both in terms of contrast, viewing angle and medium to high-volume cost.One alternative that I otherwise tested myself is this kind of display:https://www.good-display.com/product/454.htmlIt's a memory-lcd-like display (not the same as Sharp, but still with very low power consumption and high contrast) that works pretty well and is a lot less expensive that the Sharp displays.Not sure there is one that fits the required shape and size though. This one is not very large (2.9") but it's a landscape form factor.

author: golden_labels
author_rank: Super Contributor
timestamp: August 05, 2025, 03:18:26 pm
content: Dave: you did wonder, how people are supposed to know to do all themakestuff without instructions. Those are standard incantations, that everybody building software on Linux, BSD, and a bunch of other platforms knows by heart.Quote from: Whales on August 02, 2025, 04:12:01 amThat’s a weird explanation, given it’s not only not *nix specific, but Windows enforces the same since the 90s. In fact Windows takes it to a whole new level, storing that information down to specific users, not merely owner/group/others categories.The reason you might have missed it isexactlythe same reason why Dave couldn’t execute the file. Using the FAT filesystem. It was designed as a simple filesystem for floppies. Never thought as something that years later will become a dominant filesystem for desktops and removable media. As such it misses any security measures or the means to store relevant information. So if you use FAT, both Windows and Linux are unable to do access control.The difference is only in how the situation is handled. Windows just turns off most of security, when a FAT system is mounted. In Linux it depends on the mount options. In most distros the defaults assume that media which are not expected to contain executables are mounted withnoexecflag.Quote from: Whales on August 02, 2025, 04:12:01 amThe reason is that “.” wasn’t in Dave’sPATH. And it’s not anything *nix specific. Windows and even MS-DOS require this variable too. It’s the list of places, where executables are searched for when you invoke them by a name (not path).The only difference is that Microsoft’s systems forcefully prepend “.” toPATH,(1)while in *nix systems you are free to make the decision on your own.The reason for this choice in MS-DOS is obscure, but convenience is far from the most plausible explanations. It would be too anachronistic. I’d rather guess it’s keeping user experience compatibility with CP/M or an afterthought to address some issue.IfPATHdoesn’t contain “.” and one wishes to have it in the search path, it can be added. Though note that, while executing through a tool that elevates privileges (likesudo), multiple user’s environment variables are not respected for security reasons. Windows does the same, for the same reason. This includes thePATHvariable.(1)Though Microsoft fixed that and allowed this behavior to be disabled. By setting theNoDefaultCurrentDirectoryInExePathvariable. I don’t know, when exactly this has been added, but certainly wasn’t available in DOS/Win9x. Must be something in the NT line, and not in the early versions either.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 05, 2025, 06:36:08 pm
content: QuoteIt looks more like an ED-209 to me.

author: EEVblog
author_rank: Unknown
timestamp: August 05, 2025, 11:50:24 pm
content: Quote from: SiliconWizard on August 05, 2025, 02:28:08 pmI explained that in the video, it's for flexibility.The uTimer is not actually a new project for me, I have a older desig that used a customer LCD display, and I was half way through designing graphic for the custom screen.QuoteThanks, that's the first viable alternative someone has pointed out. 27uA average consumption and fully reflective.Activ area is same width as the Brannan one. I wanted a bit bigger, but it's not a show stopper.Price is pot on, and has STM32 demo board, sold out thoughhttps://buy-lcd.com/products/gdtl029t51

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 06, 2025, 12:52:29 am
content: Quote from: Doctorandus_P on August 02, 2025, 05:16:46 pmAside from measuring temperature, what would you use an ADC with a PGA for? Like, at that level of capability, a cheap Chinesium oscilloscope is what you want, right?

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 06, 2025, 01:18:06 am
content: Quote from: EEVblog on August 05, 2025, 11:50:24 pmThey have currently 3 of them here:https://buyepaper.com/products/gdtl029t51With some luck you can grab them for testing. But of course you should email them to see how easy it will be to source for production.

author: EEVblog
author_rank: Unknown
timestamp: August 06, 2025, 02:45:19 am
content: Quote from: SiliconWizard on August 06, 2025, 01:18:06 amThey said MOQ is 1000, samples available but that website says sold out and doesn't allow orders. Asking about the demo board.

author: Rdx
author_rank: Contributor
timestamp: August 06, 2025, 02:44:22 pm
content: Awesome, project time!The backlight can be used as a visual indicator, like multimeters do it in continuity for example.Also I feel like adding a counter mode would be great (IIRC you once made a hacky counter out of a calculator, for testing some sketchy battery thing?)

author: thm_w
author_rank: Super Contributor
timestamp: August 06, 2025, 10:49:09 pm
content: ST7302 and ST7305 and reflective seem to be the keywords, they are used for epaper but also ultra low power TFT as well.LHF290TB-F07 $4 ea:https://www.alibaba.com/product-detail/2-9-Inch-168x384-Mono-TFT_1600986524274.htmlhttps://www.alibaba.com/product-detail/Low-power-Display-2-13-2_1601215810764.htmlTT420FSN10Ahttps://www.alibaba.com/product-detail/4-2-Inch-300-400-Mono_1601256487381.html4.2" but limited info

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 07, 2025, 02:06:51 pm
content: Quote from: thm_w on August 06, 2025, 10:49:09 pmAh yes, I used one model with the ST7302. I had looked on Aliex where they used to be sold, but there doesn't seem to be any now. But they are on Alibaba directly. Thanks for the pointer - I don't always think of looking on Alibaba.

author: BrianHG
author_rank: Super Contributor
timestamp: August 08, 2025, 12:53:10 pm
content: Just a comment on e-paper and their pixel refresh life cycle.Quote from: EEVblog on August 04, 2025, 02:14:38 amCan you please offer a citation here for the GoodDisplays's of other manufacturers displays.I can only find around ~5 years of life if you cycle a seconds digit every second, 24/7.I would not use them if you are animating everything 24/7.For a clock with a seconds digit cycling, I guess after 10 years you will get a few dead pixels in one of the segments of the seconds numeral as each segment doesn't blink on and off 10 times a second as numbers keep segments alive or dead for multiple counts between 0 and 9.---------------------Found it hidden in GoodDisplay's website FAQ, 5 years or 1m refresh cycles where Google says 90m refresh cycles.Ok, do not use GoodDisplay displays.

author: thm_w
author_rank: Super Contributor
timestamp: August 08, 2025, 11:21:18 pm
content: 1M appears to be the standard in datasheets I find, some just say "5 years" with a refresh once per day.Apparently the previous gen was only rated for 100k.1M cycles * 1s = 11.6 days1M cycles * 1min = 694 daysThey selleink clocks, I wonder how those look after a few years of use.

author: EEVblog
author_rank: Unknown
timestamp: August 09, 2025, 01:36:49 am
content: Quote from: BrianHG on August 08, 2025, 12:53:10 pmI have ordered their TFT display and a demo board. Normally they don't have a demo board for that model but they said they make one up for me.

author: EEVblog
author_rank: Unknown
timestamp: August 20, 2025, 05:32:31 am
content: Part 2:

author: hans
author_rank: Super Contributor
timestamp: August 20, 2025, 01:47:27 pm
content: Looks like those displays are (also) made by Osptek:https://yuyinglcd.com/products/1/17/261They have a few different variants, and more spec sheetsThere is also a 4.3" screen with 400x300 resolution, which also comes in red/black/white colours:https://yuyinglcd.com/products/1/17/359Current about 30uA. But I agree it may be a bit too large.There is also 2.9" with even higher resolution AND 8 colour modes:https://yuyinglcd.com/products/1/17/389Although I can't find a picture or documentation which colours it has, and how it looks like.In my opinion, having a few colours to use can enrich the user interface quite a lot (especially if they can be matched with like device ports etc.). But it may also be a bit of feature creep.Anyhow.. 15-25uA is indeed quite low quiescent power for a display.The other part is of course also updating the display such a low power level. Especially sending the display data will take a few ms at a relatively high current. The display controller can receive bits at ~32MHz. The display has ~63k pixels, so takes around ~2ms to write a whole frame.Say thats done once a second: 15uA / (2ms/1000ms) = 7.5mA max allowed for the MCU. For a 64MHz MCU (2x32MHz), it must run at <=117uA/MHz. Thats not incredibly low, but using a MCU thats a few years older won't cut it neither (e.g. STM32L1 is almost 180uA/MHz even though its a low power series). So perhaps something to consider..

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 20, 2025, 01:53:44 pm
content: Quote from: EEVblog on August 20, 2025, 05:32:31 amWhat I didn't see, is any mention of how often one can update the LCD.The controller can do 32 MHz SPI (30ns minimum write clock cycle), but that's not what I'm thinking about. The prototype obviously refreshes the LCD at quite long intervals, perhaps once a second (and the initial sweep takes even longer), so is there a limit to how often it can be refreshed before degradation occurs?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 20, 2025, 02:09:10 pm
content: Quote from: Nominal Animal on August 20, 2025, 01:53:44 pmThat's the just the chip spec - sometimes this reduces significantly due to signal integrity ( or lack of) on the flex

author: hans
author_rank: Super Contributor
timestamp: August 20, 2025, 02:35:42 pm
content: 32MHz SPI is plenty fast for a monochrome display. Send pixel data at just 2MHz and it will still hit 30fps. A colour display will have 16-24x more bits to send. In my experience, I've been able to drive those easily at 20-30s of MHz over 10-20cm of dupont wires + a cheap breakout PCB.The LCD datasheet of the Osptek is almost identical (including the current graph). It does specify a 30ms response time (the Good Display leaves that spec blank though). I don't see a cycle/refresh limit in both datasheets. It even has a footnote stating to periodically refresh the display in case of bit errors, so artifacts are not persistent.It wont change the power scale target (uA/MHz) much though. However, being able to send data faster can be nice to have the MCU run in its most efficient MHz range (which does not mean always use the PLL with "race to sleep", your mileage may vary).The current graphs that are shown in the datasheet do seem to refresh the display once per 1.8 seconds by the way. Perhaps ~15uA is just for quiescent and ~25uA is while its being written to once every 1.8s. So certainly updating the display at 10Hz won't be nearly low-power (also consider the I/O power when it needs to charge say 20pF of I/O line capacitance at a few hundred K cycles/second).(Here is a rough calculation for 2 I/Os at 1MHz)Not sure why their current graph shows such a long active time for the screen refresh, maybe there were sending pixel data very very slowly to get the current spikes down.

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 20, 2025, 02:55:03 pm
content: Quote from: hans on August 20, 2025, 02:35:42 pmIt just piqued my paranoia. Usually when information is provided in that way by a company, it is their sneaky way to tell-but-not-tell about fatal flaws in their product.You know, "Oh! But the datasheet explicitly specifies 1.8 seconds between refreshes! The way you're using it, the lifetime is only 100 hours." or some such. Or maybe I've just dealt with bad companies too much!

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 20, 2025, 05:47:58 pm
content: Quote from: Nominal Animal on August 20, 2025, 01:53:44 pmThere is no possible degradation of any kind that I know of when refreshing it fast. It's still LCD, not ePaper. The only difference is that it can hold charge more or less long with minimal extra power, depending on some internal bias voltages. The "refresh rate", which is really akin to how long the image persists between refreshes is programmable via the controller. The ST7306 supports refresh rates from 0.25 Hz to 51 Hz, so that's ultra-flexible. You can set higher refresh rates (of course at higher power draw) when you need to animate stuff and then set a much lower rate when the image stays still. The change is effective on the next frame.

author: BrianHG
author_rank: Super Contributor
timestamp: August 21, 2025, 02:41:02 am
content: I was under the impression that active matrix TFT displays had a transistor right at each pixel to hold the picture so you may refresh as slow or as fast as it will allow.In this setup, pushing out a frame really quick, with a long 1 second pause would mean that during that pause where the image is held by the TFT active matrix, the power consumption will be close to 0.Refreshing as fast as you like and as many times as you like will not deteriorate a TFT display.Holding a still frame for minutes without a refresh to inverse the polarity on the active pixels would be equivalent to feeding DC in to a normal LCD segment display if the TFT holds the charge that long without a refresh. Such long static un-refreshed images might DC damage the LCD unless the onboard controller was designed to do a minimum refresh to prevent DC burn-in. This may also be under software control for those who need absolute minimum power consumption.

author: EEVblog
author_rank: Unknown
timestamp: August 21, 2025, 03:27:20 am
content: Quote from: hans on August 20, 2025, 01:47:27 pmIt's already feature creeped to hell.

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 21, 2025, 12:16:53 pm
content: Quote from: SiliconWizard on August 20, 2025, 05:47:58 pmIn theory, absolutely, yes. It is only using electrostatic fields to change the orientation of (fluid) molecules, after all.In practice, however, there are details, like additives within the liquid crystal fluid, and in the interface between the fluid and the electrodes.I fully admit I am paranoid in this because of bad experiences with other companies playing with info/specs like this, until I see a clear statement from the vendor or manufacturer. By paranoid, I mean "unreasonably suspicious without any actual evidence or real indicators". It is very likely that you are right and I am wrong! I just cannot shake off my suspicions yet.If I were Dave, I'd make sure and contact the vendor to ask (if, other than increased current consumption, there are any adverse effects from high update rates up to say 50 Hz).

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 21, 2025, 12:21:07 pm
content: Quote from: BrianHG on August 21, 2025, 02:41:02 amAnd yet, even TFTs suffer fromimage sticking, which occurs if you always refresh to the same state for very long durations (hours, days, weeks; it varies).Theory is one thing (and I too know full well how LCD and TFT tech worksin theory), but practice is another.

author: tszaboo
author_rank: Super Contributor
timestamp: August 22, 2025, 10:49:32 am
content: I watched the new video about this.Dave, you should dive a bit deep into the settings of the LCD. There is probably a contrast setting, which usually is completely undocumented, which value is the best. Best is to play around with it, before making a decision.I had the same issue on one project, new LCD, looks rubbish with original code, everyone calls out that I made a bad decision. Then we changed the code, and it was just as good as expected.

author: stefan_o
author_rank: Regular Contributor
timestamp: August 22, 2025, 02:36:35 pm
content: Hey Dave,just saw your video on the new display and that looks impressive. I didn't even know such a display existed, I was under the impression that the only low power options are standard LCD or ePaper, with LCD having bad contrast at non-ideal viewing angle and ePaper cannot be updated fast.I think there is quite some interest in that display and as you cannot buy it in low quantities, any chance you might sell it in your shop (if you use it for the uTimer)?Best regardsStefan

author: 3dgeo
author_rank: Frequent Contributor
timestamp: August 22, 2025, 05:01:59 pm
content: Quote from: EEVblog on August 20, 2025, 05:32:31 amI skimmed tru and didn't see someone mention so I will:This LCD kinda odd - LCD driver has 264H x320V and LCD itself is 168(H) x384(V) – that means smaller res than claimed or not "clean" internal buffer to pixel mapping. LCD datasheet does not give RAM to pixel LUT.In vid Dave mention dual frame buffer – no, that is not how it works, it has only 1 frame buffer and scans matrix from it regularly (refresh rate can be set via registers). For a change, this LCD flex has a TE pin (most other small LCDs, for some reason, do not bring this pin out even though the driver has it). TE pin is used to let MCU know that LCD driver is not updating LCD from internal frame buffer and it's safe to send new data (avoids tearing effect). Noticed some talks about SPI – SPI speed will not be issue at all, as data is writen to internal RAM, not LCD itself and only 1bit per pixel.That glitching when refreshing full screen, seen in the video, don't think is normal, perhaps code/setup/power issue?Would love to play with this display, tho I don't have use for it. If someone know similar quality half size (~200*~200px) let me know.

author: EEVblog
author_rank: Unknown
timestamp: August 23, 2025, 02:51:41 am
content: Quote from: stefan_o on August 22, 2025, 02:36:35 pmI might do that.

author: Simmed
author_rank: Frequent Contributor
timestamp: August 23, 2025, 05:36:47 am
content: since you are already using LCDthe below info probably does not matter because it is LEDi have some chance to step into and muck around inside a small commercial kitchenthey use programmable timers with alarms, one of them look something like the pic belowthe plastic over the button are lousy in the 1 i used (it broke)but what i really like about these timers is that it is LED (you could see the numbers a short distance away). but the numbers are a tad small and not bright enough. the alarm is mono sound, so the 8 timers have the same sound and it gets annoying because the alarm is loud.if only the LED is a tad larger and brightermaybe for easier "eye catch" ? if there is such a term ?

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 23, 2025, 06:07:39 pm
content: (In a kitchen, the buttons should be tamperproof+waterproof ones with either stainless steel or silver surface, so they can take the hit and be easy to clean. Silver would be antibacterial, too, as too many cooks do shortcuts with hand hygiene. Especially in fast food places, where such timers are ubiquitous.)Maybe Dave could ask the vendor to add some of these Good-Display displays to theirgoodisplay Official Storeat Aliexpress, now that there has been some Youboob visibility and direct interest from members? I, too, would get a couple. I suspect shipping from Australia to EU is too high for me.

author: golden_labels
author_rank: Super Contributor
timestamp: August 23, 2025, 10:19:09 pm
content: Polymer surfaces are easier to clean, as they can be completely solid and smooth. They’re widely used in medical setting. The thing is, they’re supposed to be replaced regularly, before the buttons are worn out and form breaks.Examples from Commons:nurses irritator,pumps,more pumps,bed control.

author: coppercone2
author_rank: Super Contributor
timestamp: August 23, 2025, 10:26:01 pm
content: I actually contemplated building something like this long ago to have a benchtop timer powered by a substantial battery that can do some sequencing and has easy operation, nice keys, etc.All the solutions are flimsy crap

author: stefan_o
author_rank: Regular Contributor
timestamp: August 24, 2025, 11:52:10 pm
content: Quote from: Nominal Animal on August 23, 2025, 06:07:39 pmYeah, unfortunately shipping is quite high between western countries. I don't think there is a way to send a display from Australia to the EU for 3€ as the Chinese can.I don't think Good-Display is actually producing this display, they seem seems to produce (at maximum) ePaper displays themself. I think this might be the actual manufacturer:Shineworld Innovations Limited. This display was on sale by someother seller on AliExpressas well, but it is sold out. You can still buy 1000 ore more on Alibaba (for 2.71€ / 3.12 USD each).

author: thm_w
author_rank: Super Contributor
timestamp: August 27, 2025, 11:45:29 pm
content: Yes I linked to the shineworld alibaba store above, you can buy 1 display for $3.80 and shipping is $14 to canada.I'll send a message to the ali seller.

author: stefan_o
author_rank: Regular Contributor
timestamp: August 28, 2025, 03:47:24 pm
content: Quote from: thm_w on August 27, 2025, 11:45:29 pmGreat, I found two items in the shop. Not sure if they are the same display, cannot find the difference, except for the modul number:LH290NB-F07-E1LHF290TB-F07Does someone know what the difference is?

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 28, 2025, 04:07:26 pm
content: Quote from: thm_w on August 27, 2025, 11:45:29 pmTheLHF290TB-F07 athttps://www.alibaba.com/product-detail/2-9-Inch-168x384-Mono-TFT_1600986524274.htmlis very tempting, but I don't like the fact that to order from Alibaba, one has to provide their phone number as well.As I haven't bought from Alibaba before, I'd get free delivery (for one to four displays, I think).I'm already having quite heavy-handed email filters to get rid of ad-mail from sellers on eBay/Aliexpress/Banggood, and the (small!) risk of getting spammy calls or SMSs on top of that is too annoying for me.Quote from: stefan_o on August 28, 2025, 03:47:24 pmLatter is thinner, 0.8mm±0.1mm, whereas former is 1.1mm±0.2mm. For some reason, a brightness is listed for the former. Otherwise the General data match.The pinout for the second one is cropped out of the drawing but seems to be revision B, whereas the first is revision A. The visible parts of the drawing match with changes in placement only, except for the thickness.

author: themadhippy
author_rank: Super Contributor
timestamp: August 28, 2025, 04:41:28 pm
content: QuoteDont need to be yours, i feel sorry for the poor bugger in bedford(uk) whose phone number is 567890,they must have received hundreds of phone calls for me

author: stefan_o
author_rank: Regular Contributor
timestamp: August 28, 2025, 05:18:58 pm
content: I just wanted to the buy a few displays, but after I registered/logged in shipping got way more expensive (same region, no address given so far), it's now almost 40€ for 6 displays. I think that is way too much.Even shipping from Australia would probably be cheaper, considering this is almost no weight or size.

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 28, 2025, 06:38:06 pm
content: Quote from: stefan_o on August 28, 2025, 05:18:58 pmAhhh, I read the offer wrong! They charge 19.34€ shipping for a single display, but offer free shipping for one unit for first time Alibaba buyers. Yep, too much for me too. (I usually buy at least two panels even when just playing with or doing an one-off, just in case I damage one. Helps a lot with debugging.)

author: thm_w
author_rank: Super Contributor
timestamp: August 28, 2025, 10:59:52 pm
content: These shipping prices are just sample shipping, they expect you to either not care or order a few and then ask them for a quote for 1000pc. So you can always message them if you really want 5pc.Quote from: stefan_o on August 28, 2025, 03:47:24 pmThe "E1" variant is cheaper, $3.50/ea and $25 for 5pc shipping.Quote from: Nominal Animal on August 28, 2025, 04:07:26 pmI can order it for you if you want, but then you'd have to give me your address which you probably don't want to do.Phone number is useful for shipping if the address doesn't quite match up or the person doesn't answer the door. But it will increase spam calls yes.

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 28, 2025, 11:30:21 pm
content: Quote from: thm_w on August 28, 2025, 10:59:52 pmHeh, it's notthat, I'm not that private. I've registered with my phone number to all the local shipping companies I use (Finnish Post, DHL, Fedex), and have provided detailed information about myself to several members here via PM. Being factual/traceable/verifiable/up to my word is way more important to me than privacy.I use this pseudonym to remind myself that all responses I get are based on my output, and not my person, which helps me interact online much better (more rationally and less emotionally) with others. I cannot change who I am — and nobody should need to —, but I can change how I communicate with others to yield better interactions, and using a pseudonym can help with that. I do prefer others to use it in PM's and emails even when they do know my real name and details, too, because it is also a fun multilayered pun to me.Right now, I don't get any spam calls or mail (because Finland), and email I can filter. With AliExpress and Banggood, I use dedicated email addresses on my own host, so I can tell when the sellers I've bought from there add me to spammy mailing lists, and use filters that do not affect my other email addresses.I also have to use heavy adblocking (uBlock Origin + NoScript), because I find ads so irritating. If I had to choose between internet access with ads, or no internet access, I'd have to choose no internet.

author: thm_w
author_rank: Super Contributor
timestamp: August 29, 2025, 08:01:42 pm
content: Confirmed with the alibaba seller shipping cost is ~$20 USD for 5pc of either type, to Canada.The offer is still there for nominal or maybe others.You'll also need a 24p 0.5mm FFC breakout, I don't know if they sell those:https://www.aliexpress.com/item/1005004413040859.html