Technical Blog

How About That Tablet?

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Last year I announced that I would spend a good chunk of 2015 working on the creation of a freedom-respecting tablet computer. How did that go?

Well, first, unsurprisingly, I ran into the massive wall of companies-will-not-talk-to-you. I only managed to get a tiny number of PCAP vendors to even begin discussions with me, and even fewer were willing to sell me prototyping gear. I spent too much on some stuff that ultimately wouldn’t work well (too bulky/heavy) but that I’m still tinkering with anyway. However, back to where I started, I eventually got in touch with people at Chalkboard Electronics about doing custom/bulk orders. They will do very small (MoQ 100) custom board spins (for simple changes like “please use LVDS directly instead of a built-in HDMI converter”). I have tested their generally-available hardware with my Novena and it works quite well.

The software situation is overall much better than I expected. Many GNOME applications support multitouch gestures already, and there are several on-screen keyboards that work reasonably well. Auto-rotation of the display on the Novena is a pretty simple shell-script. Though getting a browser that works well might be some more effort.

The battery situation turned out to be more complex than I had imagined. There is no (that I have found) good, free-design USB battery charging + passthrough solution. Maxim proved to be pretty willing to sell an eval kit for their MAX8895 series if I want to try building a solution based on that. The Novena and PiTop both use a higher-voltage barrel-jack charger, which could work for a tablet but is not ideal. The PiTop ended up going with a “smart battery”, so there is not reusable part to try there. I have an extra Novena battery board that I hope to experiment with this year and get it to power alternate SBCs.

I also got distracted this year, not least of all by my Free Culture project which resulted in a (very) small-run print of the Big Buck Bunny Board Book, of which I gave one to my niece for Christmas.

Also making good-looking progress is LKCL’s projects at rhombus-tech. While he has some strange ideas, he seems very close to executing on the laptop design and has been quite willing to share information about his suppliers, etc.

So where next? Am I going to really build a tablet for sale? Probably not any time soon. But I’ve learned a lot, and will keep tinkering with the hardware that I have. Maybe I’ll get a battery charging solution working this year, that would be nice.

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Stephen Paul Weber

There are some generic 1-cell USB charging + passthrough solutions i’ve found, but they tend to trickle-charge and don’t support negotiating for a higher charging current, etc.

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