Author Topic: EEVblog #1241 - Power Up Display Counter Project - Part 1  (Read 1883 times)

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Online EEVblog

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EEVblog #1241 - Power Up Display Counter Project - Part 1
« on: August 26, 2019, 11:32:56 pm »
Looking for a segmented e-ink / e-paper display solution for a power up display counter module project.

 

Offline floobydust

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #1 on: August 27, 2019, 12:00:09 am »
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.
 

Offline bitseeker

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #2 on: August 27, 2019, 01:43:02 am »
Oh, the joys of keyword-stuffed product listings. The bane of online shopping. >:(
I TEA.
 

Offline Rutger

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #3 on: August 27, 2019, 01:45:00 am »
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?

 

Offline johnlsenchak

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #4 on: August 27, 2019, 01:46:41 am »


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, 
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Offline Nick Norton

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #5 on: August 27, 2019, 09:47:45 am »
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.
 

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #6 on: August 27, 2019, 11:27:13 am »
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.
 

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #7 on: August 27, 2019, 11:28:06 am »
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.
 

Offline kelemvor

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #8 on: August 27, 2019, 03:46:16 pm »
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
 
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Offline gardner

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #9 on: August 27, 2019, 04:20:05 pm »
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.
« Last Edit: August 27, 2019, 04:44:46 pm by gardner »
--- Gardner
 

Offline floobydust

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #10 on: August 27, 2019, 08:43:55 pm »
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.
 

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #11 on: August 27, 2019, 08:56:27 pm »
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".

Quote
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.
 

Offline kelemvor

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #12 on: August 27, 2019, 10:26:18 pm »
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.
 

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #13 on: August 28, 2019, 12:27:53 am »
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.
 

Offline Brumby

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #14 on: August 28, 2019, 12:47:00 am »
(I thought you made that quite clear from the outset, Dave.)
 

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #15 on: August 28, 2019, 02:57:10 am »
(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.
 

Offline SparkyFX

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #16 on: August 28, 2019, 05:35:53 am »
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).
Support your local planet.
 

Offline Chupacabras

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #17 on: August 28, 2019, 02:02:37 pm »
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.
 

Offline Yansi

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #18 on: August 28, 2019, 02:26:36 pm »
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,...
 

Online thm_w

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #19 on: August 28, 2019, 09:58:00 pm »
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
 

Offline jonovid

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #20 on: August 29, 2019, 10:56:00 am »
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 
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Offline kelemvor

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #21 on: August 29, 2019, 02:10:47 pm »
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.
 

Offline ipscell

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #22 on: August 30, 2019, 06:22:59 pm »
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.
« Last Edit: September 01, 2019, 10:37:39 am by ipscell »
 

Offline Kilrah

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #23 on: August 30, 2019, 07:53:49 pm »
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.
« Last Edit: August 30, 2019, 07:58:17 pm by Kilrah »
 

Offline kentfielddude

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #24 on: August 30, 2019, 08:57:35 pm »
 
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Offline ipscell

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #25 on: August 31, 2019, 07:30:03 am »
Found this e-ink display on Taobao. Claimed to work down to 2.3V. I think this could be better compared to a segment because it allows smaller size and easier MCU interfacing.
https://item.taobao.com/item.htm?spm=a230r.1.14.130.56721a21xd94y2&id=588912154396&ns=1&abbucket=20#detail

Search query: 电子墨显示

Also what do you think about mechanical counters like this one? Just plug a motor into it and make it stop after 1 revolution. You can even 3D print these and get any size and digit number.
« Last Edit: August 31, 2019, 11:27:28 am by ipscell »
 

Offline westfw

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #26 on: August 31, 2019, 10:10:00 pm »
Quote
Bistable ChLCD. Seems like a good alternative to e-ink and memory LCD.
Whatever happened to cholesteric liquid crystal displays, anyway?  (these will retain an image with zero power; exactly the sort of thing Dave is looking for.)  I remember "Kent Displays" showing up at trade shows touting the technology, and it's "low cost manufacturing on flexible substrates", but Kent seems to have become a consumer products company ("BoogieBoard"), and it doesn't look like the tech has passed on to anyone else (or at least, it hasn't shown up in the mass market) :-(IIRC, driving the chLCD was a bit problematic, but I didn't think it was worse than ePaper.  I recall several "simple" displays being sold (batter gauge with a couple of digits and a bar graph, etc.)
 

Offline Fungus

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #27 on: September 01, 2019, 01:41:32 am »
Also what do you think about mechanical counters like this one? Just plug a motor into it and make it stop after 1 revolution. You can even 3D print these and get any size and digit number.

There's also those mechanical counters they put in arcade machines to count the coins:

Just send them a voltage pulse and they tick up by one. Zero power needed to maintain the display between pulses.
« Last Edit: September 01, 2019, 01:47:24 pm by Fungus »
 
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Offline Twoflower

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #28 on: September 01, 2019, 12:48:10 pm »
By the way the still active 6 digit e-ink display (SCB721001 at Digikey, Pinout) should not be soldered down, but use a connector (https://www.te.com/usa-en/product-5-1734592-0.html). The same goes probably for most of the flex ribbons that show up. I don't think they're supposed do be soldered at all.

Still there's little how to actually drive it. But probably like described in chapter 6 here from a different display.
 
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Offline RFZ

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Re: EEVblog #1241 - Power Up Display Counter Project - Part 1
« Reply #29 on: September 08, 2019, 03:31:52 pm »
Hey,
I accidentally came across a category of products that actually use very small low power 7 segment digits: OTP Security Cards
These are usually credit-card style or actual credit-cards that integrate a small ePaper display to show OTP or other access tokens.
Examples can be found here: https://www.smartdisplayer.com/products
These manufacturers also implement custom OTP algorithms and different form factors.

I also came across a video of someone who made his own ePaper display (not the one linked few posts before, but pretty similar). It's really just creating the electrodes on a PCB and bonding a ePaper display foil on top. So I guess making your own or ordering small quantities of custom displays from china is not that expensive.

Btw: Something that wasn't mentioned in the Video at all is the fact that ePaper Displays take a long time to update. Do you somehow want to make sure that the display always updates correctly? You may need a buffer cap to ensure the update finishes in case the product is powered up for a second or less...
 


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