Printing a handheld PC

Many thanks for posting all the specs. It's fantastic!

Jake

Thank you to everyone for your comments, I really appreciate it.

I'd never have got this far with it if it wasn't for everyone's ideas and encouragement on this thread, as well as just knowing that there are others out there with similar ideas.

The 3D printer really helped speed up the process as I was able to physically try out a lot of things as I went and didn't have to get it 'perfect' in CAD beforehand.

I'm making some decent progress with the 'power management', I've managed to get it to turn off the screen, USB ports and networking when I press my 'power' button (and back on instantly with another press) as I want it to behave as much like a HPC as possible. Still got a good amount of work to reduce the power usage in this state though, the lack of any real power management (like a standby state) on the Raspberry Pi means it all has to be implemented manually. However I believe (based on the amount of stuff that can be turned off) that it will be possible to get the power consumption down to the point where it has about a day and a half of standby, putting it roughly on a par with a modern smartphone (low bar to clear I know).

I have to admit I've been toying with the idea of turning the whole thing into a kit a little like the Noodle Pi stingraze bought. There's quite a bit of simplification and 'design for assembly' needed before that's a possibility though. Focus for the moment is on getting the current machine working like a proper HPC.

I think offering it as a kit bundle is a really good idea. I'm sure that there will be buyers. You might be able to kickstarter it too for enthusiasts and hobbyists alike.

How good are the pre-defined power management settings in RPI Android or ChromeOS builds? Have you tried running it with one or the other?

I've only tried Raspbian so far, I wasn't even aware Android or Chrome OS worked on the Raspberry Pi at all (in any usable capacity at least). I'll give Chrome OS a go with my spare SD card and see if it does any power management (and perhaps even if I can figure out what it's doing and implement it in Raspbian). Chrome OS might be quite a good fit for the device as well (better touchscreen support than Raspbian), though I'm not too keen on how dependent on internet access it seems to be.

How about upgrade to Windows IoT core

No GUI. It's acceptable for headless use though.

Somebody must be using IoT Core on the Pi for something, but I've yet to see it..

It might be possible to run some version of Windows CE inside an emulator on the Pi if we're after the real HPC experience.. Not sure how usable it would be though. Maybe something to play with once I'm happy with how it's running in general.

I've so far failed to get Chrome / Chromium OS to run on the machine, sadly. I think I need to tell it the screen resolution manually in a config file like I do in Raspbian, but I've no idea where that file would be or if it works in the same way. Some more research needed I feel..

In the meantime I've managed to add the bluetooth radio to the devices I'm able to turn off in my 'standby' mode in Raspbian. I've also ordered one of those little USB power meters so I can measure power consumption as I play with various settings, rather than trying to estimate it from the battery drain. It's never going to approach a proper suspend mode but I'll see how far I can get. It's still basically 'instant-on' and I will try and maintain a balance between that and standby time.

Minor update:

Slow progress this week, mostly minor tinkering with power settings as previously mentioned. Next steps are some sort of basic GUI to show battery level and adjust power settings (tray icon if I can) and then tying user settings into my standby program. Never touched Python until this project so this may take some time, but I'm finding plenty of help online, and it's quite enjoyable seeing my code speak to the hardware. I'll hold off a little bit while I try again to get Chrome OS / Android (thanks C:Amie) to run though, if either has any power management features that work on the Pi it would save me 'reinventing the wheel', interesting as that may be.

I discovered a flaw in my design: Not looking what I was doing I managed to put the Micro SD card under rather than into the card slot, and it's now wedged under the Pi meaning I have to open up the case and unmount the Pi to retrieve it. Not a huge job but not very user friendly! Well worth looking at blanking off the area around the card slot in future versions. Ideally I'll make it so I can't 'lose' the card inside the case at all.

Making use of the 'downtime' the 3D printer has while I'm tinkering with the software side of things, I'm adding a second extruder to it. This will allow me to print dissolvable supports and multi-material parts, should give me a lot more freedom in part design for future versions of the HPC.

Taking inspiration from the Noodle Pi (thanks again Stingraze) I am also looking into reducing the number of fasteners used and simplifying assembly where I can. Lots of techniques to be borrowed from 'real' electronic devices, though I would hope to avoid where possible adding frustrating and fragile plastic tabs and clips. Another design challenge...

Very cool. The things you can do with a 3D printer. We're using 3D printing and raspberries in lots of different instrumentation these days. Inexpensive and versatile. Keep up the fantastic work.

Edited by H2OGuru 2019-02-01 5:32 AM

Speaking of Noodle Pi, my Noodle Pi's damaged LCD miraculously recovered (it was damaged and was black in several portions of screen). Strange....
Anyhow, I look forward to your updates!



Edited by stingraze 2019-02-01 7:01 AM

Computed Axial Lithography (CAL) might be the 'Holy Grail' of 3D printing: https://www.youtube.com/watch?v=rS2P0n3_DBo&feature=youtu.be&platfor...

'Lawrence Livermore National Laboratory
Published on Jan 31, 2019
It looks like something you might find aboard the Starship Enterprise. A projector beams a three-dimensional video into a container of photosensitive resin. The video plays while the container rotates for a few minutes — then the fluid drains, leaving behind a complete, fully formed 3D object.

Though it seems like science fiction, it’s not, thanks to scientists and engineers at Lawrence Livermore National Laboratory (LLNL) and the University of California, Berkeley (UC Berkeley), who have developed a new high-speed 3D printing method called Computed Axial Lithography (CAL). The method is described online in the Jan. 31 edition of the journal Science.

“This is a breakthrough in the space of possible methods to do additive manufacturing,” said LLNL engineer Maxim Shusteff, a co-author on the paper. “What this approach does is make it possible for interesting polymer parts to be made much more quickly, which is often a bottleneck, and we can now think about using materials that don’t work well with slower layer-by-layer methods.”'

That is an amazing technology.

I found another person printing and building a Handheld PC formfactor device by himself on YouTube.

It runs with Raspberry Pi Zero.

Raspberry Pi Zero UMPC Build - 03
https://www.youtube.com/watch?v=Duhkc55RuQQ

Also for those who want to take it easy:

How To Make Mini Laptop at Home
https://www.youtube.com/watch?v=pFho9bYt6Us




Edited by stingraze 2019-02-04 10:29 PM

As this extract says, I did think of the replicators on Star Trek as soon as I saw this. Would certainly put my (FDM) 3D printer to shame - it took me about 10 hours the print the base for my HPC.

Almost no progress since last time I'm sorry to report, I've discovered after spending many hours trying to get it to work (and blaming myself) that the new Micro SD card I'd bought was a counterfeit one. So annoyed! In the meantime I'd repurposed the card out of the HPC so it's been out of action for most of that time. New (genuine) cards arrived yesterday though, so I can finally get back to playing with it!

Just a quick update - my project is still alive!

I've not done anything significant on it in quite some time as we were redecorating and the 3D printer got put safely out of the way for several months. It is now back, however, and in its own enclosure so it need not be disturbed. Also upgraded my CAD setup (ancient laptop -> desktop with 24" monitor) so I should be able to get my design work done a little more easily.

I have been slowly working on slimming the casing down and simplifying the design. However my work has been so slow that the new Raspberry Pi (4B) has been released in the meantime. The 2GB and 4GB RAM variants especially would make for quite a versatile machine, especially as it now has 2 HDMI outputs so I could allow for an external display. However its increased power requirements could pose a problem as the battery board I'm using is already borderline with the Raspberry Pi 3 B+. Looks like another round of buying and testing boards is in order.

Some notes / criticisms from playing with the machine in its current form:

+ Raspbian and its included software work nicely on the 7" screen. Resolution (1024 x 600) is just about enough.

+ Booting and loading software (from a decently fast MicroSD card) is pleasantly quick. 30s or so to desktop from power on, a few seconds for browser / office apps.

+ Footprint of the machine is noticeably smaller than a 10" netbook, so it feel like it 'has a point' if this makes any sense.

+ 'Instant on' (as implemented very inexpertly by me) is pleasing and quite HPC-like. I know laptops and smartphones more or less do this from standby, but there's usually just enough inertia to make it slightly frustrating for me.

- Raspbian (and any of the other Linux distros I got to run on it) is not at all touch-optimised. Chromium browser works as Chrome would on a tablet (swipes etc), otherwise it's single touch and you're using your finger like a big clumsy stylus.

- 40mm is just too thick. It makes it feel like the prototype it is.

- I left some of the edges where I thought there would not be much contact with the hands as I liked the visual effect. There is contact with the hands. It is not pleasant.

- The support layer under the keyboard flexes too much and makes typing difficult.

- It feels a bit too heavy for its size.

- A bit too much flex in parts of the case.

On the basis of the above I've decided the following for the second prototype (subject to change and open to suggestions):

1. It's definitely getting thinner, by at least 10mm overall.

2. Either I go to a resistive touchscreen and include a stylus, integrate a pointing device, or move to a different OS or GUI. Reluctant to move away from Rapsbian if using a Pi as the 'brains'.

3. I need to hold together the case parts at more points to reduce flex, but I want to reduce the number of fasteners (especially visible ones). Probably going to have to incorporate tabs and slots, at least in places.

4. Moving from 18650 cells to a prismatic LiPo battery will reduce weight and increase space efficiency. Got to think about protecting it from impact though.

5. I wanted to use a Raspberry Pi for the level of support and user community around it. However there are other SBCs that have built-in battery charging and proper (hardware) standby. If I'm now contemplating OS options other than Raspbian I wonder if the lengths I'm going to in order to use a Pi are truly worth it.

Sorry this is so long - it was just meant to be a quick update!