EEVblog #1241 - Power Up Display Counter Project - Part 1

[EEVblog]

Looking for a segmented e-ink / e-paper display solution for a power up display counter module project.

[floobydust]

e-paper or e-ink displays require high voltage, around 30V so extra parts required like a ~10-stage charge-pump or DC-DC converter. You have to go through some hoops to prevent latch-up on power down.
I think they are good for graphics and always-on displays but that is uncommon. I rarely see them used.
Energy to start up and update the e-paper seemed to be greater than leaving a low power LCD with MCU on all the time, that can be less energy for 7-seg stuff.

[bitseeker]

Oh, the joys of keyword-stuffed product listings. The bane of online shopping.

[Rutger]

I might not understand what you are trying to do, but why don't you use an eeprom to store the count and when it turned back on you can display the number on an LCD?

[johnlsenchak]

Something  like that type of counter  would be good for  a application  like a computer and or   server  to count how many  restarts and or boot ups  of the operating  system
over a period of time, 

[Nick Norton]

You say you need it for a power up display counter module project.
With the display always on. While I'm not sure of your drive requirements.
Mechanical pulse counters are often used to indicate how many times something has been powered up.

[EEVblog]

I might not understand what you are trying to do, but why don't you use an eeprom to store the count and when it turned back on you can display the number on an LCD?

it will be stored in EEPROM, but I want the display to be visible when the product (that has no battery) is turned off.

[EEVblog]

Energy to start up and update the e-paper seemed to be greater than leaving a low power LCD with MCU on all the time, that can be less energy for 7-seg stuff.

Not concerned with the energy it takes.

[kelemvor]

e-paper or e-ink displays require high voltage, around 30V so extra parts required like a ~10-stage charge-pump or DC-DC converter. You have to go through some hoops to prevent latch-up on power down.
I think they are good for graphics and always-on displays but that is uncommon. I rarely see them used.
Energy to start up and update the e-paper seemed to be greater than leaving a low power LCD with MCU on all the time, that can be less energy for 7-seg stuff.

The e-ink parts in the video said they would work at 5v or 15v.  Here's the datasheet from one of them: https://media.digikey.com/pdf/Data%20Sheets/E%20Ink%20PDFs/SCB721001_12-7-16.pdf

[gardner]

I think they are good for graphics and always-on displays but that is uncommon. I rarely see them used.

Likewise.  Until last week when my local grocery supermarket switch every single shelf pricing label to little e-ink displays about 30mmx50mm.  They show the same info as on the old card stock labels they used previously.  They are two-colour ones (black/white/red) and they use red for on-special items.  The little units look to have an infrared sensor for programming.

Edit: I should have waited.  Dave has now waffled over this entire topic.

[floobydust]

The e-ink parts in the video said they would work at 5v or 15v.  Here's the datasheet from one of them: https://media.digikey.com/pdf/Data%20Sheets/E%20Ink%20PDFs/SCB721001_12-7-16.pdf

Yes, for a non-mux LCD the drive voltage is lower, but no datasheet explaining "15V or 5V drive voltage" and what the compromise is. Only product briefs are available as teasers. 49 MCU output pins needed.
That 7-seg display seems to have zero benefit over a conventional reflective LCD with always on MCU.

The e-ink that look useful can display barcodes in a grocery store, I guess an RFID session might work to program a price/barcode and then walk away, for a batteryless price tag.

[thm_w]

Yes, for a non-mux LCD the drive voltage is lower, but no datasheet explaining "15V or 5V drive voltage" and what the compromise is. Only product briefs are available as teasers. 49 MCU output pins needed.

Its interesting because of the OR part, its not 5 to 15V. Which could imply there are different models or compromise as you say.
Note that the line below that gives two values for static power draw, 0 and 0.5uA. Maybe with 5V drive you need static power for some reason to sustain it? Or its just a typo and should be "active power".

That 7-seg display seems to have zero benefit over a conventional reflective LCD with always on MCU.

Better contrast ratio (probably), no need for battery/supercap, and its cool tech.

Anyway, definitely worth Dave asking them for some samples and trying it out, IMO. They will be happy to send out samples if you pay for them, from what I've seen on alibaba.

[kelemvor]

e-paper or e-ink displays require high voltage, around 30V so extra parts required like a ~10-stage charge-pump or DC-DC converter. You have to go through some hoops to prevent latch-up on power down.
I think they are good for graphics and always-on displays but that is uncommon. I rarely see them used.
Energy to start up and update the e-paper seemed to be greater than leaving a low power LCD with MCU on all the time, that can be less energy for 7-seg stuff.

I thought the benefit was that it didn't require any power to indefinitely display whatever is currently shown. It only requires power to make changes to the display.  I might be mistaken but I think Dave said in the video that this is why he wanted e-ink.  For LCD, it's going to require some power source when the device it's counting cycles on is turned off or unplugged.

It's kind of funny that the tablet sized e-ink displays are common but tiny ones are rare.

[EEVblog]

e-paper or e-ink displays require high voltage, around 30V so extra parts required like a ~10-stage charge-pump or DC-DC converter. You have to go through some hoops to prevent latch-up on power down.
I think they are good for graphics and always-on displays but that is uncommon. I rarely see them used.
Energy to start up and update the e-paper seemed to be greater than leaving a low power LCD with MCU on all the time, that can be less energy for 7-seg stuff.

I thought the benefit was that it didn't require any power to indefinitely display whatever is currently shown. It only requires power to make changes to the display.  I might be mistaken but I think Dave said in the video that this is why he wanted e-ink.  For LCD, it's going to require some power source when the device it's counting cycles on is turned off or unplugged.

Correct.

[Brumby]

(I thought you made that quite clear from the outset, Dave.)

[EEVblog]

(I thought you made that quite clear from the outset, Dave.)

I thought I did, but there are tons of comments as if no one heard it. But hey, it's Youtube.

[SparkyFX]

They say the average attention span is dropping, it must have consequences somewhere... 
But anyway, there is not much distinction on ali* between E-Ink and LCD, as if they define it just as "good readability"/"high contrast". Can´t really blame them, E-Ink is more or less marketing speak, EPD has higher chances to produce some results, but LCD will always be mixed in.

Unfortunately the search does not allow to exclude search terms (tried -$keyword, !$keyword, w/ and w/o quotes).

[Chupacabras]

I doubt about that supercap plan B.
Supercaps have huge leakage currents AFAIK, so it can hold charge just for weeks or months at best.
They are not suitable as direct replacement for chemical cell at this moment.

They are suitable for appliances that are regularly plugged to another power source so supercap is regularly topped up.

[Yansi]

e-paper or e-ink displays require high voltage, around 30V so extra parts required like a ~10-stage charge-pump or DC-DC converter. You have to go through some hoops to prevent latch-up on power down.
I think they are good for graphics and always-on displays but that is uncommon. I rarely see them used.
Energy to start up and update the e-paper seemed to be greater than leaving a low power LCD with MCU on all the time, that can be less energy for 7-seg stuff.

Quite a lot used in our country lately. Large electronics malls use them for price tags,  bus stops use them to show the time schedules for buses, trams and trains,...

[thm_w]

I doubt about that supercap plan B.
Supercaps have huge leakage currents AFAIK, so it can hold charge just for weeks or months at best.
They are not suitable as direct replacement for chemical cell at this moment.

They are suitable for appliances that are regularly plugged to another power source so supercap is regularly topped up.

I've used a cheap one from china (0.1F), and it lasted more than a few weeks powering a RTC.

But you are right that manufacturers suspiciously leave it off of their datasheets:
http://www.elna.co.jp/en/capacitor/double_layer/catalog/pdf/dx_e.pdf
https://content.kemet.com/datasheets/KEM_S6015_FY.pdf

The one reference I can find is a murata measurement of 1uA. Which seems very high and does line up well with your weeks figure:
https://www.murata.com/~/media/webrenewal/products/capacitor/edlc/techguide/electrical/c2m1cxs-053.ashx

[jonovid]

if you fully define your E-Ink unit  giving it features others can use.
maybe you can have 1000 unit's made and let 990 go to be sold to others?
I like the idea of a universal E-Ink display counter module that can used for any thing from
an hr counter to your power-up to a days used counter.  but you do need an accurate description to tell the Chinese
as this maybe an original idea? your the man Dave    at lest the use of an E-Ink numeric display in a counter module.
one idea is odometers used in cars , trucks stationary engine hours counters as other uses.
...and yes the average attention span on yt is dropping 

[kelemvor]

Dave could probably put together a small project kit for something and resell them to us as part of a kit.  1000 kits would probably go in a day if it was reasonably priced...and he could make some cash on the deal.

[ipscell]

You can also make your own e-ink display. You can implement the control circuit on that same board. Looks convenient to me.
And you can look on GreenPAK programmable matrices (they even have an appnote for an LCD driver), these might be suitable for your application since 5V is enough for driving a e-ink, you just get longer updat times and ~20% lower contrast compared to 15V. They don't specify sleep current in the datasheet though.

W.R.T. power storage, take a look at li-ion VARTA CoinPower or other rechargeable coin batteries. Or maybe use a conventional AAA battery or small li-ion battery like we saw in a Vion multimeter since we got a lot of horizontal space

Some more stuff you may find interesting:
Bistable ChLCD. Seems like a good alternative to e-ink and memory LCD.
A 24 segment driver IC in QFN36
MCU with integrated EPD driver. Only available as a die but some PCB assembly houses offer wirebonding, like these chinese epoxy blobs. It might be cheaper than conventional packaging.
Bistable display driver in QFN88. It's all about keywords, yeah.

[Kilrah]

A lot of those keyword-ridden listings are usually kinda placeholders for sellers who make a single listing for "anything we can get" that isn't of any use in itself, you're supposed to contact them and say "well I want an e-ink display" and they'll answer with what they've got for that, which will likely be the other ones you found individually somewhere else anyway.

I think the supercap/memoryLCD solution is good. Also no idea why you'd want 2 years of display time... since it's not like a powerup counter is so useful in something that isn't used for many months, and even if you get to the point where the supercap is empty all you've got to do is power the thing up and you get your number (+1, but meh). Could even add 2 pads on the board so you can power just the board to have a look.

Also normal LCDs that need to be driven have been used for decades in digital watches with several years on a coin cell, so it's not like that uses a ton of power.

[kentfielddude]

I found this e ink segmented display on aliexpress

https://www.aliexpress.com/item/32903185842.html?spm=2114.12010612.8148356.5.57c33698FoSDQ8