Tiny ePaper shield for Photon


#1

I recently picked up my Photon and played around with it using the Sparkfun Micro OLED screen. I am still amazed by the nice browser-based editor and the OTA updates; and how quickly it was possible to get code running.

I really like EPDs, the company I am working for (Plastic Logic) actually manufactures eInk-based ePaper displays (roughly compareable to the one used in the Kindle). Generally the advantage of ePaper displays is that they can keep their image content visible even when the MCU is powered of, which can be pretty nice for power-limited, e.g. battery driven projects. If your project demands rather static image content, changing only a daily, hourly or minutely basis, then you just need some milliamps to change the image content itself, thats it!

So I tried to control one of these displays via the Photon. First on the breadboard, then via PCB. It now works fine, you can see a short demo here:

To address the display I used @peekay123’s nice GFX-library and modified it slightly to work with the controller used in the EPD. It now roughly supports standard and fast updates, automatic temperature dependent waveform selection, fonts and some gfx stuff.

I am now thinking if I should continue this project and if so how to proceed. Experimentally I further tested a small accelerometer which adds a simple touch simulation to the EPD shield. By tapping or double-tapping on the screen you could start/stopp events or wake-up the Photon from deep sleep. This could also be useful for portrait/landscape detection.

So a wild idea would be to develop now a new shield with an 1.1" ePaper display for the Photon as a plug and play solution. From the outline it could look roughly compareable to the Sparkfun Mirco OLED shield. The resolution of the display would be a bit higher, enough to display e.g. the system status, timestamps, short messages, twitter tweets etc.

As a general question, are there be more people interested in such an 1.1" ePaper shield for the PhotonElectron/Bluz? Or are there already other screen shields available besides the oled shield from sparkfun? I have seen some tinkering solutions around repaper.org but so far no really nice plug and play solution yet?! I would really like to realise a project like this but would be interested in your feedback first before spending too much time on it.

Please let me know your comments. Thanks!


#2

@RobP, nice work! I like the idea of a plug&play EPD display so I don’t have to worry about power supplies and timing, etc. What are the GPIO requirements for the unit? The accelerometer idea for touch emulation. :grinning:


#3

Hi, agreed, very nice idea and I also like the accelermeter idea. I would want to get one…


#4

Many thanks for your reply!

@Peekay123 You are right the driver IC would do all most of the hard work around generating the voltages and timing ;-). Besides four SPI channels the IC needs one further GPIO pin to reset the IC and one optional GPIO called ‘busy’ (to sense when an image update is over, which is good if you want to make fast updates sequentially). The accelerometer would need one GPIO pin for chip select and a further pin if we would want to wake-up the Photon button-less via finger-tap :smile:


#5

Ok here a snapshot how it could look like (hopefuly you can see an animated gif):

And here an alternative approach:

What I like better at the second design is that the PCB side with the screen has no components anymore. So maybe it could be easier integrated in a housing and used as a frontplate.


#6

I prefer breakouts with a connector so I can mount the display separately of the Photon :laughing:


#7

I would be interested as well. Can you daisy chain the displays as well?


#8

Sweet display!

We have done extensive work getting the Sharp Memory LCD displays up and running and I love the ultra low power and high readability of them in direct sunlight situations.

Can you tell us what the power consumption info is on the screen in the video?

Also what sizes of screens do you have available? The max size for the Memory LCD is 4.4 inches.


#9

I would be very interested in this. In the mean time, do you have a link or a datasheet for the display you used in your video?


#10

Hi folks, thanks and I’ll try to answer step by step

@topshelftech In theory it should be no problem to control several displays via SPI from one Photon. If you share all six GPIOs then you can mirror the same display content to several displays (e.g. to realize for whatever reason a cube with a ‘6’ on all six sides ;-)) If you want to show different content then each display needs a separate line for SPI chip select. I am not sure about the ‘reset’ pin; maybe you can still share it (in this case one could realise a cube with six different numbers and the ‘6’ always on top :wink: ). I could try to test this once I am back from holiday…

@RWB I also like the Sharp Memory displays and I saw a very long discussion in this forum :wink: In my eyes, readablility of eInk panels is even better (but maybe I am not the right, independent person to judge :slight_smile: ). The power consumption of the shown display is roughly 5mA@3.3V for the duration of an image update (typically~0.6s). The value also depends to some extend on the image content. Larger displays will draw more power. PL manufactures displays between 1.1" and 15.4". Most of these designs are unfortunately customer-specific and not freely available. With the size the price and complexity increases significantly… Thatswhy I would prefer to start with a small display first.

@Eric24 Sure, pls find here a link from the PL website. Most likely I would envisage a slightly different, newer display design. I will keep you updated in around two weeks…


#11

To be compatible with other shields, do you have recommendations/wishes about the to be used pinout? Shall I stay with A2…A5 (SPI) or use D2…D5 (SPI1) or make it both available and selectable with a solder point? - thnx


#12

As an update below a demo of the new ePaper shield now with accelerometer…
Sequence: The photon is sleeping deep, than wakes-up after tapping, does something & updates the screen and then goes back to deep sleep.

There are two more hand-soldered prototypes available. If anyone is interested in testing pls send me a mail.
I am focusing now on the documentation… and will release it here later-on…


#13

Will we eventually be able to purchase the displays? I attempted to reverse engineer the kindle e-ink but getting a good supply of the display is the main challenge for e-ink. :slight_smile:


#14

What is the resolution of the screen in the video?

Will larger screens be available?

Does the Paperino have to come printed on all the screens bezels?


#15

@RWB, I’m sure they can customize your displays to say “Ryanino” :stuck_out_tongue:


#16

@kennethlimcp The displays & shield will become available at crowdsupply.com in about two months.

@RWB The resolution is 148x70 pixel (1.1"). Larger screens (e.g. 4.0") are for sure possible but software needs to be ported to work with Photon before. You can run the ePaper screen without any bezzel just with a tiny driver PCB. I am planning to offer such a bezzel-less “tinker set” at crwodsupply too since you are not the first asking for that :wink:

@peekay123 What would be the specification for “Ryanino” :smile:


#17

@RobP, that’s easy. The Ryanino has to be a BIG display and must be low power. It’s got to be sunlight readable also. Oh, and it needs to be really cool, just like yours!


#18

Sweet. I’ll pick one up from your crowdsupply once it’s live so I have one to play with along with the Sharp Memory LCD’s.

Be sure to post a link when it’s live.


#19

Awesome project! :slight_smile: Since we’re on the topic of tiny E-ink displays… Adafruit makea a slick E-ink Pi Hat for the Raspberry Pi Zero: https://www.adafruit.com/products/3335 I thought they had one for their fether line too, I guess I was wrong. Not promoting other products, this just reminded me of that.


#20

Ok the library now supports the BLE-based Bluz microcontroller too (besides Photon & Electron). Looking next at the Raspberry Pi Zero…

The campaign at Crowsupply will start in about ten days.
If you are interested pls subscribe here: http://bit.ly/2ot9fKw

Rob