ATREUS


Build Log: Atreus Deck Mark IV

previously

2019-09-02

The strap issues with the Mark III are proving to be troublesome; no matter how the strap is set, it always tips forward or backward when worn. And when it's not worn, the hinges just flap open. In addition the separate battery board is very cumbersome. I think it's time to revisit the design.

The Mark IV will be a more conventional laptop-style build without a hinge. I'm going back to the Pine64 (but not the Pine screen); for the time being I'll stick with the HDMI Elecrow screen as it's easier to work with, even though ideally I'd be able to avoid HDMI I don't want to add that challenge for a prototype.

first cut of the chassis in cardboard

first cut of the chassis in cardboard

My first attempts were simply cut in cardboard in order to spot problems quickly, which of course did occur. Placement for the protruding components on the Pine64 took several attempts to get right. The screen bracket works surprisingly well, although it takes a lot of force to get the friction-fit pieces together once cut in wood. Placing gaps so the screen-holding pieces can slide over the components on the screen took several tries.

rear view of the screen bracket

rear view of the screen bracket

2019-09-04

the keycaps in place in a wooden case

the keycaps in place in a wooden case

Got the main chassis cut and the keyboard wired up; I'm using the Atreus2 physical layout with 44 keys, which (since I don't have any Atreus2 PCBs on hand) entails cutting a classic Atreus PCB in half with a hacksaw and hand-wiring the middle 4 keys. It's a bit tedious but it gets the job done. It's certainly a big improvement over hand-wiring the whole thing. This build uses Kailh speed copper switches. I'm using a labeled keycap set because I don't have any other Cherry-compatible caps on hand right now.

underneath with bottom plate removed

underneath with bottom plate removed

The sides between the top and bottom plate are open with just a few wooden washers holding it open. The only thing missing at this point is the display cable; there isn't enough room in the case for a typical HDMI cable, so I ordered a flat ribbon-like one that is on its way.

2019-09-14

from the front with a stylish faceplate

from the front with a stylish faceplate

The display cable arrived, and I also cut a faceplate to make the screen look less barebones.

rear shot showing cables and power

rear shot showing cables and power

The Elecrow screen has a USB micro port for power input, and it has GPIO pins on the back that are designed to let a Pi plug directly into it. This means that some of those pins are 5V and GND, so I'm wiring those over to the GPIO power input pins on the Pine64.

At this point the device is operational, if limited in use due to having to be plugged into a power source.

2019-09-21

worn over the shoulder with one hand on it, in operation

worn over the shoulder with one hand on it, in operation

I attached a shoulder strap which allows it to be mobile along with my Anker 8000mAh powerbank. It puts out a steady 2 amps, which is enough to power the Deck for quite a while, though it's awkward to have to carry it separately, and the location of the power port isn't great.

I have several lipoly batteries I could use to run it without the power bank, but they have 2-pin connectors, and the Pine64 needs a 3-pin connector so it can determine the temperature of the battery and avoid overcharging it and starting a fire. So that's probably not a good thing to cheat on. I have several 3-pin batteries from old mobile phones lying around, but soldering onto those is also very dangerous, and I can't find the connector terminals for sale in smaller quantities.

The biggest annoyance using it right now is that you have to shut the whole thing down to switch between battery and AC power.

2019-09-29

sitting on a lap, used to write this document

sitting on a lap, used to write this document

I think at this point it might be time to call this prototype complete and start over on a Mark V build which takes the lessons learned and designs from the start with battery placement in mind. I found a slightly smaller HDMI display from Waveshare which should be much sharper than my current one. I decided against ordering another Pine64 display because it's too big, it's got a bad aspect ratio, and I don't have a lot of faith that if I order another one it will actually work. I should probably build a heat sink into my next one if it's going to be used for anything other than SSH.

Finally, it would probably be simpler to wire the keyboard directly into the copious GPIO pins, which will remove the need for the keyboard controller currently in use. I know drivers exist for direct matrix scans over GPIO, but I don't know if any of them support layouts with layering in them, so that will be an adventure to look into. That might need to happen for a Mark VI or later.

I've placed orders for the parts I need for a Mark V:

I've already got some of what I need on hand:

I would also like to add a control panel to the left of the screen which could hold several LEDs and a few toggle switches, but that should probably wait until the basics are ready.

To be continued...