Make I2C accessible in some way (docking or solder pad on board) [answered]

Well, so we have to hope we are lucky in the way that routing them is possible without too much effort. Of course I can't say how much effort it is, only Jolla can make a statement on that, as they are the only ones that have access to the necessary infos and layout. I guess that in principle, routing the pin out is possible, else it would not make sense for Intel to offer it. Of course a complete pcb redesign would not be trivial to do, and maybe even too costly.

Just I think that if it was possible without too much effort, it would be a nice thing to do. Because pins that are not routed at least to somewhere on the board are dead and will never be usable in any way. Think "fm radio issue" on Jolla phone. While, even if there would be no way to have an official docking port with those pins, having them routed just anywhere where they can be accessed by someone skilled in soldering and electronics opens up some possibilities to tinker around with it, given one is ready to take the risk.

So what about a simple separate chip providing a useful interface (I2C/USB/GPIO/SDIO/RS232/whatever, which is itself connected to one of the "internal" available interfaces (could be even over internal USB).

@dac: Sometimes there is not enough routing space to exploit all of a chips functions. As they are sometimes designed with many features and it is up to the user to select the ones they really need and want. Which also means that often not all pins can actually be routed.
@MartinK: Such chip will still need routing and pins etc... it is possibly even more complex than exposing the pins.

@Philippe De Swert Understood. So let's just see how it is in this case. If it is impossible, well, there is nothing we can do about it. If it is too much effort or cost, sure, it would be a waste to spend much money or huge effort just for having the pads. But if it can be done with less effort, why not? I can't say. I'll be happy for a statement of Jolla on whether it is possible/feasible or not (in this specific case)... :-)

Edit: I appreciate the answer. So have a look on what is possible with reasonable effort using and possibly modifying the board you are going to use. Would be cool to have this, because it would open quite some possibilities in my opinion...

@Philippe De Swert: Sure, not all - what I mean is that actually about any of these interface that can be routed to suitable outside pins will do! :)

It might not be high speed, full featured or might even some quite obscure type of interface but as long as it is here, it can be used for doing interesting things. It would be also another first - after the Jolla being the first widely sold mobile phone with a generic third party expansion interface, the Jolla tablet can be the first such extensible tablet. :)

BTW, I think (and anyone more knowledgeable please correct me! :) ) that this is what a suitable interface should provide (if possible):

• interrupt support - the accessory can notify the main device, so that the main device does not need to continuously poll the accessory for eventd. The current TOH interface has an interrupt pin and this alone makes the TOH keyboard project practical.
• power out - the interface can power the accessory so that the accessory does not need its own power source
• power in (optional) - the accessory can supply power to the main device (battery packs, wireless charging, solar panels, etc.)

IF these "conditions" can be met with one of the available interfaces, then fully featured accessories/TOHS/docks, etc., can be made for the tablet.

But even if some or even all of these "conditions" can't be fulfilled, it would still be worthwhile to include the interface as ti would still be useful and because it is easier to supplement the missing functionality given the tablet form factor (include a battery, an on/off switch, etc.).

Anyway, thanks a lot for joining the debate from Jollas side, much appreciated! :)

Well, I was not saying they should spend hundreds of kEuros for it. But as the interface is there, it would be nice to have it accessible, if it is not too much effort.

I know that the keyboard is the only project that got significant attention, and which you can buy now or soon, but there are other people who tinker around and try out things...

see e.g. Kimmo Lindholm with eink display, oled display, FM radio

If it is realized as solder pads, it would mostly be for hackers or people who have some skills and interest in modifying things and "making". It is not meant to be for people who just want a tablet for doing normal stuff. A bit more "unlike"...

True. I could only think of a second one: https://together.jolla.com/question/17605/could-the-camera-shutter-trigger-be-made-available-through-i2c/ But it'd be vastly less popular than an external keyboard...

And talking "unnecessary" features, I think everyone can name a lot of features in phones, tablets or any other products that are, for part or sometimes even most of the audience, unnecessary. Talk about (all for phones now): 3d cameras, cameras with 42mpix, 3d display, fullhd, widi, miracast, usb2go, nfc, fm radio, fm transmitter, voice control, microhdmi, millions of apps in app store, root access, smartcard reader, exchangeable battery, expandable memory... etc etc... There are always some people claiming that this or that feature is unnecessary for them. And they are right, subjectively, because they don't use it. I guess many of these features are not needed or extensively used by a lot of people owning the devices. But still, this is about potential. And I2C does deliver some possibilities. Not for everyone, agreed. The same that 3D printers are not useful for all, or arduino boards, or raspberry pi... or gpio on those...

The Jolla phone didn't have the I2C for keyboard only. The same that the raspberry pi had the gpio not for a specific application. But it delivered a "general" potential and possibility to add it. And something else can be added too, if enough people join up to do it. What that can be is up to the users. And that is one aspect that I like. Look at all those capes, shields and hats available for those boards that you can buy. There it just took the critical mass. Jolla is just not there yet, but who knows about the future...