m9365428, having that be a volume knob isn't a bad idea. I will think about it. In-game it doesn't seem to have any function. It does rotate on the Pip-Boy edition.
The other knob being screen brightness is also a good idea, especially if I eliminate the ambient light sensor. The side knob is supposed to be a scree focus knob, at least according to the art book.
I have considered doing a hidden button behind the scroll wheel, either one that can toggle between two positions, or toggle a function. I was thinking of using a capacitive switch, which is far easier to do since I have very little room for a mechanical switch. Two capacitive switches together could even do scroll-up/down. The hard part is that since the Pip-Boy app doesn't support keyboard shortcuts. (I am hoping someone at Bethesda can change that). So scrolling up and down requires that you remember your previous position.
The holotapes don't have as much internal space as you might expect. I have covered the idea of using the as a battery earlier in the thread. A 500mA battery could it inside, but they would require a secondary charger circuit, either internal or externally. Having one battery charger another isn't possible. Both batteries would be running at 3.7V, and the charger circuits typically require 5V to even operate.
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Project update:
I have already put 13 hours into the game, played until 8am the first night. I also spent some time with the Pip-Boy edition and gleaned some ideas from that.
Here are the changes I already plan on doing:
1) Change the sensor pod into a USB cable interface for charging/updating the Pip-Boy. In-game the white pod didn't turn out to be a lamp at all, the Pip-Boy still just does a bright screen as a flashlight. It is easy enough in Android to make an app that does nothing but show a green screen at maximum brightness.
2) Eliminate the IR temperature sensor. It it a very expensive single component, and does not emulate any actual in-game function. It also makes the pod more complex to build.
3) Somehow add an adjustable strap. It does help when putting on your arm one-handed to have it already held down with velcro.