Small project update:
Prototype Mk3 is now
(mostly
) functional. A few bits left to do and a few late changes to the design that came up during assembly and testing, but not far off altogether.
Working:
- LCD and touchscreen with brightness control
- Battery charging and level indicator
(built in on the board and supported by the OS so no credit to me
)
- Wifi
(as above
)
- Suspend-to-idle - less than ideal in terms of power savings but properly tied into the OS so it works from the power button and triggered by timeouts etc. I get around 24 hours in 'suspend' on a full battery so a long way to go here.
Not yet working:
- Internal speakers - Essentially I didn't do enough research and my original setup
(i2s audio with individual mini DAC/amps per speaker
) was not workable. I have a simpler
(tested
) solution in the works, just some wiring and slight mods to the casing to do.
- Trackball - Not wired in yet. Needs some research in which GPIO pins I can use and then a re-working of the 'driver' I wrote to use it on the RPi. I'm also toying with the idea of setting it up so the user can choose between using it as a 'mouse' type device and for scrolling, maybe even other functions.
- Proper suspend / deep sleep - This one is a little frustrating as the hardware is definitely capable of it, it even appears to go into suspend but gets 'stuck' there and cannot be woken. The 'wake' triggers work as the same ones are used to pull it out of suspend-to-idle. This kind of issue is usually some device or driver misbehaving, in my experience with Linux
(probably other OSs too
). One to address once all my hardware is working I think.
The OS I've gone with for now at least is Armbian. The version I've got is basically Ubuntu with XFCE as the DE - Lightweight and pleasingly simple for use on a small screen. I've tweaked a few settings to get screen elements like window controls nice and big for touchscreen use. It doesn't have real touchscreen support like drag-to-scroll and pinch-to-zoom, it may well be possible to add these but in the meantime my trackball will cover the cases where the touchscreen doesn't quite work.
I did play with Android a little bit - touchscreen support was of course excellent and the sizing of screen elements was much more suited to small screen use, but the latest version currently working on the Pine64+touchscreen is 6.0, which I find a little scary from a security perspective. The deal breaker however was that it rebooted every time I put it into 'sleep' mode and I could see no easy way to get 'under the hood' and adjust system settings or try to diagnose this. I also prefer a proper 'desktop' OS on this machine as I feel it's a lot more than a tablet with a keyboard attached.
Please see the picture below. This was taken in poor lighting so the screen looks quite 'washed out', in reality it's quite a high quality IPS panel, nice and bright with the excellent viewing angles you'd expect. Better photos to follow once the hardware is complete and I've stopped taking it apart.
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