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Forum Index : Microcontroller and PC projects : could a micromite drive an e-ink panel?
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| robert.rozee Guru  Joined: 31/12/2012 Location: New ZealandPosts: 2428 |
i've been thinking around ways to build a wall clock for the elderly using a surplus e-ink display - the sort you see in ereaders like the Amazon Kindle. the ideal is to have a very clear display with: digital time, AM/PM, day-of-week, day of month, and month. the device should be battery powered (updated every 60 seconds), and be thin enough to hang on the wall like any other wall clock. a quick search on ebay reveals that 6" replacement e-ink displays for the Kindle 2 are available for about nz$20. there are many suppliers, likely because the K2 is pretty ancient and stocks of the displays will be surplus. the part number is: ED060SC4. replacement Kindle 3 displays are also available, but these have a more complicated connector; while the K2 display connector is a simple FPC tail, the K3 display connector looks like a micro-plug of some sort. the K3 display also has an onboard ROM containing unknown configuration data. a couple of people have implemented interfaces to the K2 display: http://spritesmods.com/?art=einkdisplay http://essentialscrap.com/eink/index.html the question is: how difficult would it be to hook one of these up to a micromite? note that speed of update (in the application i have in mind) is relatively unimportant, while the 60-second refresh rate (the display is powered down inbetween) would contribute towards batteries having a long shelf life. no doubt others would be able to think up other useful applications. cheers, rob :-) |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10180 |
Looks easy enough just a lot of slog work to get it working. The big issue is making a "correct" PCB to break out all the signals and generate and switch all the required supply voltages |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2931 |
I had a 'dabble' with some cheap e-ink displays (with success in terms of driving them). However, some of the e-ink displays have a surprisingly high power requirement for doing a 'redraw'/'refresh' so the power supply needs to be up to it! Also, some are quite slow at refreshing resulting in a not too pleasant appearance if you happen to look at the display during a refresh. Overall I was disappointed and will now wait for the colour ones to become available at a sensible cost. With the 'explosion' in smart watches, hopefully the technology will develop quickly. The best resource for me was 'Google'. As matherp says, as long as you drive the power pins as required, and study the datasheet, then these e-ink panels are quite easy to drive. Best of luck with your clock 
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10180 |
Here is one with the work done for you - not cheap though - and only 4.3" |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2428 |
the video clip at the 'essential scrap' website showed quite clean 'clear screen to white' then redraws that in the case of a digital wall clock would be visually passable. reading into some the the text, it also sounds like partially changing the display is possible: each pixel has 4 possible write states: black, white, 2 of no-action. it is also possible to not alter a given row. combining these, i feel it would likely be possible to only expend power altering a small area of the screen - in the case of a clock, the rightmost minutes digit would be the single area updated most often. i was surprised that the fellow at 'sprites mods' didn't use a more sophisticated power supply design - but then power consumption wasn't a big issue for him. i'd have been inclined to start off with a LM2577 module (from ebay) to boost the battery volts up to +15v, then a 555/diode/capacitor -ve voltage generator. the +/-20 is low current, so can be easily achieved seperately. an alternative (electrically simpler) route woukld be to take a functioning Kindle, and tinker with the firmware so that (a) the web browser is always launched, and (b) it is able to be shut down to near-zero power for a minute at a time. then the Kindle can connect to something that creates the clock face as a webpage that is served either wirelessly or via the debug serial port. or, since the Kindles do run linux, just write a clock application that takes over the Kindle completely! cheers, rob :-) |
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