The Raspberry Pi Zero is the new hotness right now and, frankly I've been punting around the idea of a pi based tablet for awhile. The Zero isn't going to win any speed awards, so I was thinking less 'general tablet' and more 'load epub and raw txt and read' because epub is an open standard, txt is read by everything, and project gutenberg is an info-dump that has existed since the 1970's (plus Cory Doctrow, and others have released their material under creative commons license.)
This is sparked by the fact my tablet died, I pulled the battery and was 'eh I can just run it off a wall right?' Nope! It seems to be a standard for android tablets to just not do anything if there is no battery or GOOD battery in place.
Key thing here is make it feel snappy given the limit of a 1ghz single core arm processor.
What I want it to do:
* Boot up and have a desktop that has icons for an e-reader program, and a way to sort through my library at an absolute minimum.
* E-reader software that can handle epub and txt. CBR (comicbook archive format) and PDF would also bre nice, but if not no worries.
* User serviceable battery since i don't like proprietary. I want to know that i can feed the thing in the future so i can go out and about.
* Prefer a sevenish inch total footprint (bezel and everything) across. Screen can be smaller than that, and would kinda prefer a smaller screen while keeping that size because it gives my thumbs a place to rest.
* the ability to hook into another computer to populate the e-book library.
* Tactile on/off, screen brightness, and page back/forward buttons for both lefties and righties (ie two buttons in the bezel on each side of the screen, possibly rocker switches that can easily be accessed with your thumbs.) Would be nice to have a 'home' button and or another that lets you quickly access a favorite's list.
* BONUS: Find a way to give it sound so I can plug headphones in to listen to music while i read, or podcasts.
* BONUS: Instructions for creating a case without using a 3d printer since I personally do not own one.
* BONUS: Costs less than $200 with case and buttons or costs less than $120 without case/buttons.
The difficulty for making the tablet from a Pi-Zero is as follows.
* Sourcing a screen that both isn't going to break the bank in terms of power and cost.
* Reduce the amount of overhead so there's as little demand on the processor as possible.
* A way to maximize battery life.
* Easily replaceable battery while still being functional if tethered.
* the ability to easily add/remove media.
The positives of the Pi-Zero:
* 80 Miliamp idle draw (according to spec sheet or 160 under full load. this makes it more attractive than the Pi2 or even the older generation of Pi for portable projects.
* Tiny size both in horizontal/vertical and height means we can go far slimmer than possible in the past.
* Unlike something based on the compute module you don't need to create a new PCB to socket into this, which is great for those of us not blessed with a hardware shop at our beck and call. No offense but not everyone has your budget.
The Downsides:
* Single micro-USB out so that's where all outside information not tied to GPIO has to come from. Any external media, connection to other devices, possible wifi, all of it has to funnel through that.
* No on-board LCD input so you're limited to the micro HDMI port or if you want to be bold, soldering something directly into the composite connector that needs to be populated.
* No Audio. Not as big of an issue with e-readers as opposed to tablets, but being able to plug headphones in to listen to music, podcasts, or the like would be nice.
* possible desktop/environment problems? I don't know if a tablet-centric UI for the pi exists outside of android ports.