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Comment by godelski | Hacker News Reader

Has anyone hacked the boogie board? It is extremely cheap.

Edit: Googling this seems to be a good resource [1] and it looks like it is using an msp430 so should be hackable. But I don't actually know much about this stuff, so if someone does hack it I'd love to know how

[1] http://forums.hackaday.com/viewtopic.php?f=2&t=846

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Information in that thread and elsewhere suggests that the MSP430 doesn't have the ability to display information on the screen. Drawing on the screen is a purely mechanical effect, and the microcontroller is only used to clear the screen.

More information on the technology:

http://kentdisplays.com/technology/ewriters

What's particularly interesting about these displays is that it does seem possible to read the image from the LCD (particularly the Jot 8.5 and the Sync; the others don't explicitly say). I'm trying to figure out whether the display device itself integrates memory cells or whether there's a tablet sensor overlaid on top. The website doesn't seem to want to explain much.

I'm under the impression the sync can be used to read the image, since it does have a save feature. I'm wondering if the reverse can be done too? Could you make the display show an image that was previously saved?

I'm curious why you think the jot 8.5 can save. I do know the earlier models were using an msp430, which others are suggesting cannot save the image. I actually have one of these Jots, but I don't know anything about hardware hacking so I'm not going to tear it apart (unless people just want pictures of the guts and possibly what chips are in there)

Other commentators have mentioned that the display in other devices cannot be read, and from the website it's clear to see the company focuses solely on ChLCD (cholesteric LCD) technology.

This would depend on whether the "read from LCD" capability is an intrinsic part of the ChLCD itself or a manufacture-time option, or if it's a separate capacitative or optical-barrier touch layer.

I just did a bit of digging, and I found some info on repairing the Boogie Board Rip on iFixit: https://www.ifixit.com/Guide/Boogie+Board+Rip+Internal+Anten... - this shows what looks like some kind of touch layer, along with a bunch of extra electronics.

There's also a smartphone showing a 1:1 copy of what's on the Jot on the fourth image as you scroll down at https://myboogieboard.com/ewriters/jot-8.5.

The jot uses a phone app and the phone's camera to get the picture. So I don't think there is any way to read the screen on that device.

However the sync has a button which you can save the screen image and later upload it to your computer. What I'm wondering is on this device if you could do the reverse. I know being able to record the screen's state doesn't mean you can reproduce it. Just wondering if you can in this case.

I know nothing about ChLCD and that type of stuff. So this isn't really clear to me.

Oooooh. Thanks for that information about the Jot. That's remarkably good advertising showing the smartphone on the webpage like that, I have to admit.

Regarding the Sync, I suspect it contains the same electronics as the Rip in order to do the sync thing, and a touch panel.

Based on the other comments I've read in this thread that explain how "writing" on screen (and "ink" showing up) is entirely mechanically driven, ie, the pressure on the surface of the display displaces the crystals and makes whatever you draw stay on the screen. Applying a voltage for a short moment somehow causes the crystals to reset.

I'm not sure why the display itself wasn't made writable. It's entirely possible Kent Displays simply couldn't find a viable way to market a (MCU-)writable version of this technology, and so they went in this direction instead; it's also possible that ChLCD (developed up to the point Kent have it at) doesn't have the capability to be addressed reliably. I have no idea.

I based my hunches above about how the Boogie Board resets on something I saw on TV a while ago, which I just determined is classified variously as "switchable privacy glass", "electrified privacy glass" or "intelligent glass". I learned (from the house-construction TV show) that it's essentially a single, gigantic (!) LCD "pixel", and I saw (in one of the construction stages) how simply plugging it into the wall and turning the wall switch on was what made it go from opaque to transparent. Obviously it's a fair jump from this to the Boogie Board reset mechanism, but it seems reasonable that some of the same ideas are used in both.

Then how does the sync save the display? There have been a few upgrades since the hack I found.

> Has anyone hacked the boogie board? It is extremely cheap.

It's not a software controllable display. It uses a film concept similar to an etch-a-sketch and in the recording model, it uses a touchscreen to read the pen action, but there is no pixels/no matrix and no display that can be drawn to by software.

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