OctoPrint, Z-Wave, Bluetooth, and other assorted goodies…

Or, how to waste money on automation, and have fun doing so

Payday has come around again. I was broke two days before I got paid – funny that. I fixed up my accounts this morning, and bought a Tomtop powered USB hub, for my Kinect (which hasn’t been plugged into the OctoPrint print server yet), and a Z-Wave USB stick from smarthome.com.au. Next paydays assignment, should you choose to accept it – Cooking Hacks Bluetooth Extreme module.

Getting OctoPrint to run on my CubieBoard was a snap – essentially, Linaro (Lubuntu core, actually) and Raspbian are pretty similar. It would’ve been a headache if I was using a Fedora OS, I’m guessing, but because both Linaro and Raspbian are Debian type OSes, I guessed that my Cubie should be able to run OctoPrint.

And I guessed right.

I took a screengrab of it on my Macbook, since I have no clue how to do so with Win 8s touchscreen interface. No, I don’t want to know either, thats what the Print Screen key is for. Still waiting for my Dell keyboard. Even though I wasn’t able to feed anything into the OctoPrint server in terms of data, nor get the webcam working, for the reason I don’t want to mix a definite high speed device with a whole heap of low speed devices, I was able to access the webserver fine, and once I enabled Javascript in Chrome, everything just worked.

Of course, it was a struggle to get it going on Linaro, I didn’t even have GCC or Make. Oops. Once all the dependancies were fulfilled, it just came up. Wicked!

The print server is running off a 13.8VDC power supply at the moment (the “shack” supply, for when I was playing with radios more), through a whole heap of cigarette lighter plugs and sockets, then though a 5VDC USB car charger, with a 2.1Amp, and a 1Amp output. Its meant for powering both your tablet and your phone in your car. I just find it bloody useful! Two USB out, and one of them 2.1Amps – gold!

With the long term supply of the print server, no, I won’t be using that shack supply forever, although it’ll live in the rack as a backup. Very soon, I want to go over to a “true” UPS system, based on a Winston/ ThunderSky 12VDC 90Ahr battery, a 60Amp Pro Mariner float charger, and a 600Watt PowerTech inverter for the stuff that really does need 240VAC (which is the ToughSwitch PoE switches, and the HDMi TV monitor for the print server). The rest of the equipment in the rack runs at either 12VDC or 5VDC – Extremely Low Voltage.

Now, normally, you’d need no real special qualifications to use ELV, its considered “safe” in terms of voltage – however, short out that battery, and you’ll know the meaning of fire and brimstone…! I’ve seen car batteries with cranking currents of 300Amps shorted out with a spanner when taking the terminal leads off – lets just say the spanner was vapourised. So it pays to know what in the Hell can go wrong, before playing with stuff that can release combustible fumes. And no, I don’t mean when they’re charging, I mean when they’ve been abused – over or under charged, or shorted out.

I need a dry chemical fire extinguisher in here – not only for the battery, what if one of the printers decides it doesn’t like me? Plastics sure don’t like water as well as chemicals and oils.

So, to speak of my qualifications, well, I do have a cabling licence for a start, meaning I can play games with ELV legally. Then I have a single phase plug replacement licence. Then, way back in 2005, I did a module at engineering school entitled “Telecommunications Power Systems.” Yes, yes, it was 48VDC stuff, but apart from voltage, you know if you short it, something bad is going to happen. So 5VDC and 12VDC is pretty much the same.

Not many people would have these qualifications, but I do. Unusual, but the way my life has wound around, I guess. Its nice to put all that knowledge of exchange power systems to work at last. Of course, this is my exchange.

The next thing I’m going to get is a 12VDC power switch from the States. Yeah, its a bit, and good old Mr Customs will want to have a nice long chat to me about the money I owe him for it. But its exactly what I need. It allows network control of the switching of DC powered devices (up to 10Amp per channel, out of eight channels), and has a “ping watchdog” which’ll ping the device, if the device doesn’t answer back in a certain period, it’ll cycle the power, and allow the device to reboot. Almost like an external watchdog, totally needed for embedded devices that’ll run day in, and day out.

Realistically, I won’t be switching on and off the devices all the time, in fact, if I’m doing that, then I know I have problems, like theres been a power blackout for more than the two hour runtime of the battery backup. Its a last gasp measure to keep the absolutely essential VoIP server alive for as long as possible, along with the switch that’ll provide power to the wifi APs, and the VoIP desk phones. Literally, the printer/ power server will “sacrifice” itself to keep those VoIP systems going.

So, an unknowable future, but the trend is towards VoIP in an NBN age. Of course, as I’ve mentioned, your fancy VoIP server and phones all become fancy paperweights if there is a blackout, and you don’t have any backups at all. And for me, an APC “in-a-box” system doesn’t quite cut it. I need to be able to control all parameters of the operation of the UPS system, and know if theres going to be any issues, where those issues are, can they be isolated quickly, because this system is my family’s last link to civilisation, and I take its continued and uninterrupted operation very seriously.

And don’t tell me about mobile phones – unreliable, dodgy pieces of crap. I’ve had more phones go flat in an emergency situation, or drop out, than I care to remember. The panic when that link is gone is always unbearable. And I fastidiously charge my phones every night, even if they tell me they don’t need to be charged. I know smartphone battery consumption, and Murphy’s Law all too well.

My system is meant to get around Murphy’s Law.

This is all basic, academic, planning. Redundancy is a big thing in situations like this. Ok, I won’t have two VoIP servers, or two backup power systems, or anything like that, but who knows? One day I might replicate the system to have an active failover, an N+1 redundancy. It isn’t needed right this instant, plus I’ve run out of room in my rack! But that is a thought for the future.

You want to know the best thing about this system?

Theres only about four fans in the whole system, and they’re temperature controlled. If I plug in the 48VDC rectifier (ably acting as a shelf in the bottom of the rack at the moment), then I’ll have noise, but the rest of the low powered gear doesn’t have fans, or if it does, they cut in at high temperatures, not run all the time. That means my rack can live next to my room, and be powered on all the time, and I do get a good nights sleep…!

That makes me a happy man.


About rackingwoes

In a time and a place outside of what you consider reality...
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