Printing a handheld PC

I've just bought a Pi Zero W, tiny USB hub and a 5" touchscreen (resistive) with the intention of building a HPC format device. Thinking of one of those USB tablet keyboards that connect by USB to keep things simple, I think the keyboard will be about 20 x 10 cm so would make it more Mobilepro sized (albeit with an undersized screen). My idea with the case is to machine and assemble one out of Acetal or similar engineering plastic (thankfully I have access to a tiny milling machine).

Hard bits will be the hinges and passing HDMI and USB cables through them.

It's encouraging to know I'm not the only one contemplating something like this!

You can get FPCB runs for HDMI and USB that would pass through the hinge cavity without a problem

e.g. https://www.alibaba.com/product-detail/low-cost-flexible-pcb-board-C...

You just need to pinout and solder them together.

Oh cool Roberto! We need pics of that as you go...

are you thinking something like this?


Mike...

Edited by mikeschn 2017-03-05 1:01 PM

That's brilliant, I had no idea you could get parts like that made in small quantities! I'll have to look into it.

Mike, that is pretty impressive, is it laser cut wood? Mine would be similar to that except I imagine I'd screw the case parts together.

Still very early days, I'm just playing with the touchscreen so far. I'll post photos of any progress I make.

I could put an Ipaq HX4700 in the lid part with an USB keyboard below...CE6 handheld in 30 seconds!

Also, don't know how many of you have ever built a remote controlled airplane, but Monocote, Coverite, Skintex are all plastic based sheets of heat shrink material. I could cover that wooden form and using both a hair dryer and heat iron, it would adhere to the wood like it was glued on making it really coverful and shiney and smoooooooooth...as if it were molded out of plastic.

Rich Hawley,

Okay, let's see you do it! ;-)

Roberto,

No, it's just a picture I found on the web. It appears laser cut. I only have a cnc router, so I couldn't do those fancy corners!!! But maybe someday, if I come up with a design that's worth cncing,..

Mike...

Minor update:

I had second thoughts about the Pi Zero when I realised it had no audio onboard (except via HDMI) and also web browsing was quite painfully slow. I'm not sure yet what SBC (single board computer) to use in its place, I think a Raspberry Pi 3 with the RJ45 and USB ports removed would work but I am also considering the Lemaker Guitar https://www.amazon.co.uk/dp/B01C4JOJ8S/ref=cm_sw_r_sms_awdb_bYj6ybANEW8ZX - this has built in support for charging and running from a LiPo battery and a swappable module with the CPU and RAM on, making it upgradable.

I have successfully butchered one of those cheap tablet keyboard cases as I previously mentioned, this yielded a keyboard with a thin metal backplate and a small controller board with the USB cable attached. Dimensions of the keyboard are approx. 205mm x 82mm x 5mm (8.1" x 3.2" x 0.2". Key feel is not as nice as the Jornadas and certainly not a Mobilepro 900 but easily beats a touchscreen keyboard for me. Keys are scissor switches (like a laptop / HPC keyboard) so not too wobbly and with a nice soft 'click'. Pics to follow..

Progress is likely to be fairly slow as I have an upcoming summer project (building a new garden shed / workshop) but I am determined to get this done in some fashion.

Thanks again to all for your encouragement.

Thought I should provide an update on this:

I've made little progress, the more I worked on the case design the further away it seemed to get, I think my idea of 'fabricating' it using my micro-miller was a bit of a dead end. Eventually I got a little disheartened and repurposed the parts. I made a portable game console using a plastic enclosure I bought and a game controller I'd gutted. This worked surprisingly well and I got pretty decent battery life out of the two 6000mAh lithium-ion cells I put in it. What it certainly proved is that a portable device using the Raspberry Pi (3) is feasible. Internals are as follows:
- Raspberry Pi 3
- 'Waveshare' 5 inch HDMI LCD with resistive touchscreen (referred to in an earlier post)
- s.usv 'UPS' add-on for the Raspberry Pi (provides supply for the Pi from lithium-ion batteries and charges and reports charge level)
- USB gamepad, PCB cut up and re-wired to fit
- 5v stereo amplifier PCB (about 3W per channel as I recall, tiny thing)
- 20mm (0.8" diameter speakers
- Various connectors and bits of wiring to bring the connections to the outside of the case.

To be honest although perfectly functional the ergonomics leave something to be desired, so it hasn't seen a great deal of use since I built it. I'd semi-forgotten it until a few weeks ago when the 3D printer I'd ordered from China finally arrived. I've got some fairly decent prints out of it, with a little tinkering, and it's had me thinking again about the HPC idea. In keeping with the original topic of this thread I'm going to have a go at 3D printing a casing and finally getting the HPC built. I believe 3D printing will overcome a lot of the issues I previously had with the case design as well as allow me to quickly try out different ideas. As you can hopefully see from the list above, most of the parts I've acquired for my portable console project can be re-used, and I already have the keyboard.

I think the first design will be a 'chunky' casing designed around the parts as they are (no connectors cut off, use of current 18650 batteries etc.) The device will allow me to try out the concept, screen size, and how functional the Raspberry Pi and its various OS options are for this role. If this proves encouraging I'll go further.

I'll post photos here of anything worth photographing. First step is to dissassemble the current machine and work out the required internal dimensions.

Had same idea.

However I'd love to figure out how to connect smartbook keyboard to pi (maybe via a wee adapter that can be programmed by pressing keys to convert it to a usb keyboard. and then fit a standard pi 7" screen in case.

I think I may have a solution for this: http://uk.farnell.com/holtek/ht82k629a-40diplf/ic-usb-ps2-cont-win-2000-keyboard/dp/1420877
You wire the existing keyboard matrix to this chip (probably via its ribbon cable), and a suitable connector to the chip's output and it appears to the computer (Pi in this case) as a standard USB keyboard. I bought a few of them when I was considering an idea very similar to yours - I wanted to put a Pi inside a (dead) HP Jornada 690. I dropped it when I realised there was little chance of fitting all the required bits inside (at least for me). Looking at the Smartbook it appears a more substantial machine so hopefully gutting it would provide some decent space to play with.

I bought about 5 of these chips in total (anticipating mistakes / clumsiness on my part) and if you're interested I'd be happy to post you one or several of them for postage cost.

https://www.tindie.com/products/RasmusB/usb-keyboard-adapter-for-psi...

There is also a Arduino programable interface that you can program most kayboard matrixes to USB...

Here is the beastie and should allow most ribbon keyboard to be programmed to work as USB. Not sure how chip solution would work as how do you tell it what matrix your keyboard uses. I think the wee adapter here allows you to press a key and detect which pins it makes active to program a keyboard.

If i could find a bloomin screen that would almost exactly fit hole in 5mx (whole area where screen and silk screen buttons were) then I'd be building a Pi based psion 5mx

John

Maybe we could see what largest off shelf screen we can fit in 5mx lid is and have a new front/surround plastic made for it. Would much prefer a more letterbox shape to optimise space avail but hard to find so wonder what largest 16:9 HDMI powered screen is we could find.

Looking at the dimensions of the 5MX I would say one of these two is probably your answer (dimensions shown):

https://www.waveshare.com/product/mini-pc/raspberry-pi/displays/4inch-hdmi-lcd.htm

https://www.waveshare.com/product/mini-pc/raspberry-pi/displays/5inch-hdmi-lcd-h.htm

Also worth noting that the 'lugs' with the mounting holes in do not contain any traces so can be safely cut off the PCB to buy a little space (Source: I have one of their 5 inch displays). Resolution on both are pretty high so should mitigate the reduction in size somewhat (though items on screen may be a little small).

4" no good for keyboard typing.. 5" is just on edge of useable. Sig3 was a lovely device but really needed a larger screen 6" or wider would have been perfect. So no going out my way on a project like this unless can solve some of the problems. Smartbook probs does it as be easy to fit 7" screen bit its not pocketable. 5mx or sig 3 would be perfect if could find a screen that would take make better use of space available. Could even take battery connector off a dead sig3 motherboard and wire it to the batt circuit inside so could use original changeable cells ??

Again to make it a useable everyday device for me it needs a wider screen than 16:9 at minimum something that fits old screen and silk screened touch icons of original 5mx. They can be found but not in HDMI which kinds defeats purpose as most converter solutions take too much power.

hopefully at some point a suitable screen will turn up.


Edited by mr-mac 2018-03-22 5:32 PM

How's about this in a 5mx case...

http://www.craftdata.co.uk/colour-tft-lcd/6-5-800rgb-x-320-resoluti...