Spark + eInk/ePaper?

If you guys are planning on running your inventions on the Photon in the near future then you might want to consider the Sharp Memory Displays since the Photon will have the memory available to buffer the screen data.

The Sharp Memory LCD’s are smaller, lower power consumers overall, and require much less wiring, and they are just as readable under all lighting conditions.

Sharp Has the memory LCD’s in 1.28", 2.7", and now you can find the 4.4" screens.

Sharp Has a audio recording on their resources page where their engineer talks about how low power the Memory LCD’s are and compare them to E Ink displays which consume more power overall. See the podcast audio on this page:

Just wanted to throw that out there since I’m still amazed at how good these screens are for low power applications.


Cool display! I would be suprised if it drew less power than E-ink (which is effectively 0 when holding) but I know a similar display is in the Pebble and that thing can last for days!

@harrisonhjones Yea listen to what the engineer has to say about the displays vs the eInk displays at the podcast audio at this link:

They talk about how the eInk displays consume more power over all due to the eInk displays requiring all the extra driver circuitry which consumes power which the Sharp Memory LCD does not require. They also say that the power required to Write to the eInk displays is really high compared to the power required to write to the Sharp LCD Screens.

The only thing that is required to keep the Sharp Memory LCD’s displaying a static image after it has been written is a square wave pulse on the VCOM pin which can be done via a Square Wave Generator that only consumes 1.36uA, and the 2.7" screen only consumes 20uW. You can run the screen for a year straight while only using 1/2 a Watt Hour of power.

Only wake up the micro controller to refresh the Sharp Memory LCD when needed.

So yea eInk requires no power after its written to but requires more power overall when you take into account the whole picture.

The 4.4" screen consumes 250uW when displaying a static image. You can run this for a year along with the Touchstone TS3006 Square Wave Generator chip for a year straight on like 1.1 Watt Hours of power. That’s Amazing Stuff.

That is quite impressive. I guess the advantage I see of e-ink is you can literally disconnect the displays and hand them out as business cards and there will hold. Pretty cool stuff. Both technologies are amazing. Thanks for showing the Sharp device. Where did you get yours?

Yea but due to the size and cost your not going to hand those eInk displays out as business cards LOL

Here is a whole thread on the Sharp displays from awhile back.

I just saw that the 4.4" versions of the Sharp Displays are now available so I ordered one up to test out. I’ll post pictures of it once it arrives. I’m going to integrate these into some portable battery packs I build so they can display battery status info 24/7 with virtually zero impact on Battery Life.

@Peekay just fixed up a libarary that works with the Spark Core and the smaller screens

What do you guys think of this panel?: Also in terms of porting a library for the core?

That uses the same e-paper display everyone else uses so the libraries should be effectively identical.

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Hey @harrisonhjones, have you been able to talk to your client yet? A minute ago my seeedstudio shield arrived and I can’t wait to start! :smile:

Sorry guys, don’t want to bother you with this too much. As I don’t know if @harrisonhjones could get a permission from his client to publish the seeed library I was wondering if perhaps you, @peekay123 could help me out with this? I would be very glad about any kind of support.

Again – thank you so much!

Harrison Has my permission.


Ah, you’re the client, @Dogan? :blush: Thank you very much for giving your permission – I really appreciate that. So @harrisonhjones – if your time permits it someday: I would be thrilled to get my hands on this! Thank you for all the trouble.

I got the spark core and epaper to work connected as above. But I had to lower the speed of the SPI interface. I also changed pin D5 to A7 to use the PWM functionality on that pin.

Source files:


Wow, awesome work @androw72. Do you have experience with the seeedstudio shield, too? And why is WIFI actually turned off (at least that’s what the readme says)?

No I haven’t tried it. But I guess it works in the same way.

The wlan could be turned on.(uncomment the #define SPARK_WLAN_ENABLE in platform_config.h). It was to speed up the spark start-up time I turned it off.

@HrMense, I’ll get the library posted later today (for the seeedstudio shield)

@androw72, what I think I’m most impressed with is that image. It looks fantastic! I was aware such shading was possible, I’ll have to look into it. Can I get the source image? I don’t believe the Seeedstudio library even uses the PWM pin. Is that required to get the shading?

Actually I think that the good shading is mostly due to the blurry picture… :slight_smile: but the ‘wif’ format gives quite good fading. The pic:

Here is the original from wyolum:

Regarding the A7 PWM it’s needed otherwise my screen goes black. It’s also in the connections on the seeedstudio-shield what I can understand.

@androw72, just to clarify, here is what the PWM is used for and why your display went black:

When writing a new image to the display, the panel itself requires a large voltage across it in order to drive the pixels. To achieve this without an external voltage supply a charge-pump circuit is used. The MCU must provide a PWM signal between 100 - 300 kHz in order to charge up this voltage.


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Here is a test with a seeedstudio library to drive the adafruit/repaper development shield

I didn’t get the image example to work. But the graphics did. (circles and squares)

The seeed shield has a character chip that Idon’t have on my EPD, and I don’t check the temperature sensor, it’s set to defaul 25 degree.

@androw72, @harrisonhjones: You guys just made my day. :sunny: Thank you so much! I’m going to check out both libs and report back with (hopefully) some pics.

Hey @androw72, I am about to hook up my seeedstudio shield and was wondering if you perhaps stumbled upon “M_/WORD_STOCK_CS” or “M_CKV” during porting the seeed library. I found these terms in the Arduino wiring spreadsheet on this site: but I wasn’t able to locate them even in the non-ported library. Any idea?

@harrisonhjones: Please let me know if there is anything new.