I am NOT an electronics hobbiest

People call me many things, some polite, some not, some to my face and I am sure, some behind my back. One thing I have been accused of being, and that I am most certainly not, is an electronics hobbyist.

Certainly I use electronics, and my extremely limited electronics knowledge in many of my projects, but I certainly am not interested in the electronics, for the sake of the electronics, in fact I cannot think of much of less interest to me, and whilst I can understand the point of building electronics to test and build something so you can increase your knowledge, this is simply not me. I learn what I need to know to complete a project.

This has come about as at one client they are utilising Arduino’s in an educational setting, and on numerous occasions I have been asked to help out due to my knowledge surrounding them, now this is fine whilst they are doing some basic functions, you know, hello world kind of things, but so far for example I have had no need to learn how to control or manage servo’s so when that comes up, I am of little use.

What I DO build with electronics, are things that I cannot purchase off the shelf, yes I know its lazy, but like so many others I am time poor, I only build things that I have to build to achieve an outcome that I have decided I need, often times this is with the goal of some kind of automation, or reporting on certain states to conserve time on often wasted tasks that I would have to otherwise do.

One example of this, is the Particle Phone and electronic scales I am working on for the measurement and ultimate reporting of weight of a container of hydrochloric acid that is attached to the pool. The automated systems we have in place around the pool control PH, Chlorine to Salt conversion (through the use of ORP) and temperature on the solar controller. What it does not do however is tell me and report on the weight of the remaining hydrochloric acid, meaning constant checking of this one component. This project is simply to use a particle photo (or perhaps ultimately a ESP8266) to simply read with weight from a scales and report it back, and then either generate a push message or e-mail when the weight drops to a certain percentage(s) of the original (minus the approx weight of the container obviously). This reduces my need to check the system.

What this does not make me, is an electronics hobbyist, it makes me a maker, or perhaps an assembler, cobbling bits of off the shelf hardware and code together to make a task work. A true electronics hobbyist, would design the circuits, test them and go for a far greater efficiency than I am trying to achieve, as the photon is most definitely overkill for the task at hand in this case, and perhaps an ESP8266 is as well, I do not know, I do not care, I am after a working “product” at the end that can achieve my rather simple goals.

As I said, I am not an electronics hobbyist.

Justin

The Hidden Cost of the Raspberry Pi (and other “cheap” SBC’s)

The Raspberry Pi and other small single board computers have really taken off in the past few years, especially with the burgeoning wave of development, both commercial, but mainly hobbyist of the Internet of Things (IoT) arena.

Now Raspberry Pi (I am focusing on RPi here because it kicked off the whole shebang in a big way, small SBC’s existed before then but they were not as widely available or used) was never intended to be a IoT board, it was originally intended to be used to teach programming to children. The success of this original project (with over 5 million, yes that is 5,000,000 sold) has not only spawned a myriad of projects but a whole bunch of clones and similar devices looking to capitalize on the success of the project.

With the hobbyist community getting a hold of these devices and putting them into various projects one has to question the cost of these devices. The devices for those who do not know cost US$25 or US$35 depending on the board revision however you also need to add a SD card (either standard or micro depending on revision), power supply, case (enclosure) and if needed a USB wireless dongle and you are looking at getting towards US$100, not as cheap as it sounds to be, and that’s in a basic headless configuration.

The other side to this is the environmental cost, with all these devices (remember there are 5 million RPi’s alone) floating around that will at some point in there lives end up being thrown out, and mostly into landfill it is not overly environmentally cost effective with all those electronics leaching chemicals and other materials over time. What causes this, upgrades to newer models or migrations to other platforms, or even loss of interest, the result is the same.

Now don’t get me wrong, I am not saying these systems are all wasted, or all an issue. Many interesting projects and products are developed from them, not to mention the education that people get from developing on and for these systems. What I am saying is that their use should be more specialized to where the processing power is actually required or used to aggregate the data (done through a technology such as MQTT), cache it and forward it to a more powerful management system (home server anyone).

Further to this, the idea here merges nicely with my move to containers (Docker) and my continuing work with Virtual Machines. If we take the services the RPi runs for each function and put them into a container, and that container syncing through either MQTT or directly through the applications services to a micro controller which then carries out the functions.

Why is this more efficient, because the micro controller only needs to be dumb, it needs to either read the data on the interface and report it to the server, or turn an interface on or off (or perhaps “write” a PWM value) to perform a function. This micro controller does not need to be replaced or changed when changing or upgrading the server, and can even be re-tasked to do something else without reprogramming the controller and only changing the functions and code on the mother controller node.

Much more efficient and effective. It does however have the downfall of an extra failure point so some simple smarts on the micro controller would be a good idea to allow it to function without the mother controller in the event of a failure but the MQTT controls are agnostic so we can work with that, at least for monitoring.

Opinions?

Justin

Smarter Sprinkler System

Irrigation (sprinkler) systems have come a long way since their inception, and even further since the advent of modern electronics, and with the modern Internet and the beginings of the Internet of Things (IoT) revolution they are getting smarter and are able to do more. One example of this is that where a “modern” controller can tell if it is raining, or has rained in the past period through the use of a rain guage, IoT devices such as the OpenSprinkler can now use forcast weather from the internet to make a decision about the watering. Linking this with things such as moisture sensor data can make these systems even smarter. This is however one thing that seems to be missing, the “smart” solenoid.

I am not a gardener by choice per-sey but more by nececcity, wanting to take more control of the food I and my family eat requires growing our own, which whilst easy in some respects, does chew up a lot of time.

Solonoids themselves are quite simple devices they use a magnetic coil to retract a metal (normally iron) core against a spring (which opposes the coil so the solonoid goes back to “rest” when the electrical current is no longer applied) to open or close a gate, if the gate is closed, water does not pass, open the gate, and the water flows through. Nice and simple.

What is not so simple however is the current requirement to run an entire cable pair, yes there are ways of theoretically doing n+1 (n being the number of solonoids) but in general its one solonoid its one cable (pair).

Now with cheaper, smarter, more capable electronics what is to stop us moving the “smarts” that for so long have been intergrated with the controller, on to the solonoid itself, you could then program it over the cloud, a RTC would allow it to turn on/off on a schedule, a hard link to a moisture sensor could allow it to turn on if the soil gets to dry, and cloud computing, or a local weather station could stop it watering if it has rained or is predicted to rain within the next allocated period, say 6 hours.

That gives you more smarts than are most old control boards are capable of, almost as much as modern ones are capable of.

But what if, now we have this connected to the cloud, and we can group them, in one or more groups to control when things are watered. Got tomatos that need watering twice a day but are at opposite ends of the garden, not a problem just create a group of two or more solonoids to control, put in the times and off you go, what about 3 areas, just at another solonoid, 4 areas so on and so forth.

But we are talking the cloud here…. it’s all seeing, all knowing. You could in theory not only control based upon groups, but what about plant types, if you could TELL the system that you were growing tomato’s and you could tell it how much water you want to give them, and when. If you wanted to you could even attach a flow meter to measure the amount of water delivered rather than base it on the arbitary value of time where the pressure and therefore amount of water could vary, with a flow meter you KNOW how much as been delivered.

What I am thinking is a bit light your LifX bulbs, but for solonoids. What about data, well that is easy you can do it through standard 802.11 Wireless, or how about XBEE back to a controller station, or even use a three cable wire to tap in to, using an addressing system such as I2C. In the end it does not matter so much about the how it works technically, so long as I can walk up, plug in the power (or power & data) and connect to the water piping, program it how I want and boom, it works.

Ah well we can all dream

Project: HomeMadeMonitor

Yes, yes I know I should finish other projects first, but I have yet another electronics project I want to start playing with, and this post is more for a reminder of what it was I was aiming to achieve more than anything else.

As I have been falling more and more down the self sufficient/home made produce rabbit hole, I have noticed that I need more and more data for certain things, so that I can then act upon it, or even better yet, have an automated system to act apon it for me.

The two things I am thinking of, are specifically the (dry) curing of meats such as salami’s and the aging of cheese. Both these are reliant on maintaining the right temperature and humidity within a certain range for a prolonged period of time, ranging from weeks to years depending on what your wanting to achieve. Now in the past this has been what I have been designing SafeDuino to do, and whilst that does other things in addition to monitoring temperature and humidity, some of those more advanced are not needed by the monitoring and control software.

Whilst it may be more benficial to “recycle” code from the SafeDuino project. I am finding myself drawn more and more to the Particle Photon system for these basic requirements as not only as it generally cheaper than the Arduino’s (Freetronics EtherTen and EtherMega) I have been using, but it does come with built in WiFi. Conversly I then have to supply power to the device, either through a paraciticle connection to something else, a dedicated connection to it, or a Solar/Wind & Battery solution, where as the EtherTen and EtherMega boards (with the use of a PoE module) can pull power from the PoE switching equipment I have in the house. A wired connection is always going to be more reliable and faster anyway, although the speed is irrelevent when your doing so little data transfer. Using wireless also means I need to ensure that I have wireless access at each point on the property where I want a monitor, which is easier said that done when we have a large property, much larger than any one or two wireless points can handle, although this is due mainly to the construction materials of the buildings on the property and the distances involved.

This leaves me wondering how to achieve this. Given the design of what I want to achieve, being able to control one or more chambers, through one or more devices I am thinking I need to build it as to make extensive use of 1 wire and I2C technologies, ideally linking back to a Paricle Photon (it has considerably more processing power than an Arduino) and then back to a server. Simular to what they have done with BrewPi, but this means as I said above power supply issues to due no PoE connector, and connectivity issues…

Anyway I will think on it further, but I will most likely end up using the Particle Photon.

What I need to achieve however is rather simple, as I said above monitoring one or multiple “cambers” from a single root node (the Particle Photon) and reporting the data back to a server, where it can be further processed and acted upon if need be. These “chambers” can be joined, or independent, and may or may not have one or more common components (think combo fridge/freezer where the compressor is common to both).

Each “chamber” must be capable of having unique settings (within reason, you cannot expect it to keep one chamber at 30 degrees Celcius and the other at 10, its just not going to happen if you have common components) and be able to work out how to handle this.

I guess it is time to start designing (and finishing off other projects)

Have Fun

Justin

Creating a USB to DC socket power cable (for an Iridium 9555)

**NOTE IF YOU FOLLOW THE METHODS/INSTRUCTIONS HERE YOU DO SO AT YOUR OWN RISK. I TAKE NO RESPONSIBILITY FOR DAMAGE TO PEOPLE OR PROPERTY THAT EVENTUATES FROM THIS ARTICLE**

As part of my travel kit I generally take a Satellite phone for emergency communication either out, or more commonly in from work colleagues. With my old one having died, I replaced it with an Iridium Model 9555, and whilst the phone is new, and is a current model it works along the same lines of phones from the early to mid-2000’s. Along the same lines of these phones, the phone uses a wall transformer wired into a standard DC power plug (3mm barrel diameter in this case). This leads to a plethora of adapters to keep the thing charged around the world, and adds to the things that I need to carry with me, and as you may have seen with my other posts I am trying to travel with less, not more.

2015-01-12 - DC Cable - 01 - PhoneThe Phone in Question

2015-01-12 - DC Cable - ChargersStandard Chargers & Adapters for Iridum 9555

Having a look at the chargers in an effort to see if I can eliminate them and use a charger that I already carry to charge the phone. Through looking at the details on the chargers a little measurement and testing of the chargers output 6V DC at 850mA output in a tip positive/barrel negative configuration. I found this rather interesting that it is using 6VDC, as it is very close the the USB voltage of 5V.

USB chargers these days are rather ubiquitous around the place, and with most chargers putting out 5VDC at around 1 amp and going up to 2.1 amps for tablet devices. Given this a USB charger should be able to power and charge the phone, however depending on the tolerances in the chargers output, and the phones required input it may accept a straight input from the USB charger, or it may need to be boosted through a boost converter to achieve this. Either way it means I can do away with all the adapters and simply use the USB chargers I already have to carry.

Looking at the boost converters such as the LM2577 and XL6009 based converters from eBay are capable of this, but first I want to see if I can charge the phone without the converters. Either way I need to make the same cable, with the converter if I need to add it later I can simply cut the cable and insert it in the middle.

Now to start, to complete this project only basic tools are needed; wire strippers, cutting tools, soldering iron (with solder). I used several different cutting tools but you can use whatever you want.

2015-01-12 - DC Cable - 03 - ToolsTools (Soldering Iron, Solder, Wire Strippers, Scissors & Scalple)

I also use a liquid to help the soldering process, this is called Bakers Soldering Fluid, I cannot recommend this stuff highly enough it is simply fantastic, and you do not need much of it, as such a bottle lasts for ages.

2015-01-12 - DC Cable - 04 - BakersBakers Soldering Fluid

As for the parts I used these are shown below, these include; USB Cable with a width of 3.3mm on the cable insulation which is less than the inner diameter of the hole for the DC power plug shroud which is 4mm. It is important to note that the “donor” cable is a USB to Micro cable, as all the full size cables (i.e. not mini or micro connectors on one end) were too wide to go into the plugs shroud. The DC power socket itself has a 3mm barrel on it, beyond that any plug should work. Also two pieces of heatshrink are used, one 4mm and the other 4.5mm. With this you can then create a USB to DC adapter.

2015-01-12 - DC Cable - 05 - PartsUSB Cable, Heat Shrink & DC Power Plug

The first step is to remove the desired head of the USB cable, in my case this is the Micro-USB head

2015-01-12 - DC Cable - 06 - Head RemovalCutting the head off the Cable 2015-01-12 - DC Cable - 07 - Head RemovedCable without Micro-USB Connector

After cutting the connector off the cable, the next thing to do is stripping the out insulation off the cable, thereby exposing the contents inside

2015-01-12 - DC Cable - 08 - Stripping the CableStripping the Cable

This exposes the two types of shielding that protect the inner conductors protecting the lines from EMI that can induce data errors. This shielding causes problems I will go into a below, it is however messy and causes some extra work, it is also not necessary for our purposes.

2015-01-12 - DC Cable - 09 - Cable ShieldingThe shielding on the USB cable

This shielding as per the USB specification is meant to be grounded to the chassis ground, which is no the same as the signal ground that is on the conductor inside the shielding. Whilst this shielding serves no purpose as DC jacks only have the two connections and no shield ground as there is in other connectors. In the creation of the cable can create an issue with causing a grounding loop if it is put directly against the bare metal of the barrel connection to which the inner ground (negative) conductor is to be connected to as these cables are commonly supported by the extension of this barrel connector, as such it needs to be removed as much as possible to do this we first strip it back and expose the insulated inner conductors

2015-01-12 - DC Cable - 10 - Stripped SheildingOuter wire shield pulled back, exposing the inner foil shield (Note how many wires are on the paper under the shield, this can be messy)

2015-01-12 - DC Cable - 11 - Both SheildsBoth Shields pulled back exposing the inner conductors

To make this easier I take the shields and twist them together, much like twisting the bare conductors together before tinning them to make it a cleaner job.

2015-01-12 - DC Cable - 12 - Wrapping SheildsTwisted up foil & wire shielding

Once it is twisted up, cut it off. For this I use some sharp scissors, although this could be achieved with most cutting devices, I like these scissors

2015-01-12 - DC Cable - 13 - Cutting ShieldsRemoving the shielding

Once this is done, I slip the shroud from the DC plug over the cable, and although this could have been done earlier or later in the process I find this is the best time to do it as the mess from the shielding has gone, and the heatshrink has not yet gone on, thereby expanding the cable diameter and making it harder to get the shroud on.

2015-01-12 - DC Cable - 14 - Place ShroudShroud placed on the cable

Sliding the shroud down the cable and out of the way for now I cut heat shrink just big enough to cover the end of the cable and ensure the last of the shielding that is hard to remove will not short against the barrel plug.

2015-01-12 - DC Cable - 15 - Heatshrink SizeCut heat shrink showing the size and the exposed remnants of the shielding

Once the cable is done, thread it over the cable so it covers the remnants of the shielding and shrink it into place

2015-01-12 - DC Cable - 16 - Heatshrink PlacementHeatshrink in place over the cabling protecting the remnants of the shielding

2015-01-12 - DC Cable - 17 - Shrinking HeatshrinkShrinking the heat shrink in place over the shielding remnants

Now that we have dealt with the shielding remnants, we need to get rid of the two data cables. USB cables for those prior to USB 3, use four conductors, two for power (the red and black), and two for data (green and white). Now whilst I could simply remove the cables by cutting them off I am too paranoid about shorting out the conductors and damaging the cable itself or worse one of the devices connected to the cable ends. To deal with this I trimmed the cables back short (about 4mm in length) and then folded them back over the heatshrink.

2015-01-12 - DC Cable - 18 - Conductor ColoursShowing the four USB conductors

2015-01-12 - DC Cable - 19 - Snipping Data CablesTrimming Data Cables

2015-01-12 - DC Cable - 20 - Folding Data CablesFolding the data conductors back over the heatshrink

Now I have the issue of holding them there, given my desire to do my utmost to prevent possible shorting and possible damage to devices I am going to heat shrink them down in place

2015-01-12 - DC Cable - 21 - Heatshrink SizeHeat Shrink cut to cover the Data Connectors 2015-01-12 - DC Cable - 22 - Heatshrink PlacementHeat shrink Over Conductors

Once this is in place and heat shrinked down the next step is to bare the other two conductors, and it is at this point I twist the strands of the conductor together and tin the conductors. Given how small the conductors are on my cable, I simply used my fingernails to strip the wires

2015-01-12 - DC Cable - 23 - Tinned WiresStripped and tinned connectors

It is then simply a matter of putting the conductors through the holes on the inner section of the DC plug, with the positive going to the tip and the negative going to the barrel, once they are soldered in place securely, trim the conductors as close as possible to the soldered joints, this is to minimise the interference when sliding and screwing the shroud into position.

2015-01-12 - DC Cable - 24 - Installed and Soldered ConductorsPositive and Negative conductors soldered in place

2015-01-12 - DC Cable - 25 - Trimmed ConductorsTrimmed Conductors

Once this is done, slide the shroud over the cable and you are done

2015-01-12 - DC Cable - 26 - CompleteCompleted cable

I have tested this cable on my Iridium 9555 and an Apple USB charger and it works fine, the charger gets warm as one would expect but no more warm than when charging any other phone. I have also tried in on other USB chargers and so far they have all worked fine.

Enjoy and as always do this at your own risk

**NOTE IF YOU FOLLOW THE METHODS/INSTRUCTIONS HERE YOU DO SO AT YOUR OWN RISK. I TAKE NO RESPONSIBILITY FOR DAMAGE TO PEOPLE OR PROPERTY THAT EVENTUATES FROM THIS ARTICLE**

Slimming Down (of my power adapters)

Recently I have been trying to reduce what I carry, and where I cannot eliminate it I am trying to reduce the size and weight of the items. To this end I have been fascinated by the new FINsix DART, power charger. Now there is plenty of material available out there on the web about this device, but the run down of the device is it was first shown at CES this year and its a small, yet powerful 65 Watt laptop charger. This is possible by the use of VHF (Very High Frequency) switching, thereby delivering smaller packets per switch (on/off) and thereby saving energy, and allowing the components to be smaller as they do have to use deal with as much energy at one time, but this means very little to most people.

What this essentially boils down to is a much smaller, sleeker and less bulky charger, supplying the same amount of power to your laptop (or other device).


Coin

 

Looking at this device, the size and weight reduction it offers are most certainly a good thing, and provide what I am looking for, that is not to say however there are not issues with this device.

First and foremost is the devices 65 Watts of power (which as most laptops charge at between 16V and 19V would indicate the amperage throughput is someone in the neighbourhood of 3.25 to 4.0 amps), this is however not enough for either my current laptop, which uses 165 Watts, but I am not too concerned about that as I am replacing it early next year, but it is not powerful enough to power the replacement even, which by comparison to my current power hungry beast uses only 85 Watts. This power gap I am sure will be narrowed with time, and I will undoubtedly be able to get one to power my laptop soon enough.

What is a little harder to deal with is the power plug pins. Yes I know it seems minor, and prehaps it is to others, but the bags I use for work are nice leather bags from Saddleback Leather, Pad and Quill or Kent (depends on how and what I am doing as to which I grab) all of these bags apart from being more expensive than most have leather on the interior, which the pins can scratch up and damage.

Many US adapters, including the one from Apple have a solution to this problem, retractable pins, and whilst this works for the “straight” American style pins, I have yet to see one for Australian style pins, check out the pictures below to see what I mean

 

 

PlugDifferences

 

To this end, FINsix could at least for the US make the plugs retract, but this may not be possible due to the design.

So what the fix I hear you ask, simple a cap, same as that pen that’s in your bag now, a simple cap over the pins, in the same colour as your device, that you can place over the pins when its not in use. I do have another idea, but I am unable to draw it as such currently, I will give it a shot on paper at some point in the near future and do another post about it

 

Have Fun

 

Justin

 

 

 

Travel Tips

I have been traveling much more in the past 24 months or so, both for business and leisure, so I thought I would share a few items and tips I have discovered along the way.

Firstly, travel with a power board from your own country, and then use a travel adapter to power the power board. Now with this it is important to remember several things, and make several decisions, firstly is whether make it a simple power board with no internal electronics (this means no USB chargers or alike) or a power board that does include these things and is rated for 110V-240V and 50Hz/60Hz input, most I have seen are not.

You also still need to remember that travel adapter DOES NOT change the voltage/frequency of the power supply, and neither does a power board, so you still need to check that your device is rated to accept the correct input voltage/frequency, which most common electrical transformers for portable devices (laptops, phones, cameras, etc) are these days.

To further reduce the amount I am carrying I am purchased a battery charger that can not only charge multiple batteries, but also multiple types of battery through the use of adapter plates, and do this simultaneously even if they are different voltages, and it has a USB charging port built in as an added bonus. This means I can reduce the four camera chargers (each charging one battery),  I have been carrying in the past down to one and whilst I may “loose” two battery spots, I find I rarely need to charge more than two or three batteries at any one time, and I can charge a battery, go for dinner, come back and charge the next batch, so no great loss apart from a little effort. If you need however, this device also has a 12VDC power input to charge from a standard power socket or cigarette lighter in a car. So what is this wonderful device? It is a Watson Duo LCD Charger (Available Here).

That solves at least some of the problem, so what about the rest? Well firstly it depends on what you have, in addition to the cameras I am normally carrying two phones (one local to overseas area for local calls and my work phone from home (which has my personal phone redirected to it), a tablet (USB charging), one or two battery packs (depending on time I am expecting to be away from a power source) and a laptop, and depending on the  reason for travel, again there could be another phone which is used to run some specialist software, and another one or two tablets. So how do I deal with this with only three remaining power points on your average power board, simple.

Most laptops are capable of charging one or two devices simultaneously, so I simply charge them overnight using my laptop. If I then need extra ports I can either add a PlugBug World (Twelve South PlugBug World) which adds yet another USB port, and can use many number of power input connectors. So two down, two to go. Enter the Skiva SmartQuad (Kickstarter Campaign) which gives me one left unused, bonus…

 

Justin

SafeDuino – Part 05: First Released Part Sketches

Further to my last post on the subject I have had a little time, or rather made a little time and created two boards for use in the movement of power and data from the EtherMega to where it’s needed. The first is a RJ12 connection so 4 data pins are possible, the second is a RJ45 connection so 6 possible data connections.

Both boards are double-sided, and have multiple power inputs/outputs and are designed in such a way as to be stackable either vertically, horizontally or both to allow a layer cake effect for these connections, there is a row of single header pins at the “back” for the board and you can mount either horizontal or vertical pins in it, or as I intend to do, pins at an approximately 45 degree angle, but we will see how that works.

As the boards use standard header pins for all instances it is possible to integrate them into your own circuits, however where possible I would recommend integrating the RJ12/RJ45 part directly just to eliminate un-neccicary connections and components.

Anyway eithout futher adu;

RJ12

RJ12

RJ45

RJ45

Fritzing Files

RJ12Connector

RJ45Connector

More Arduino Project Stuff

Just thought I would make a quick entry in a couple of spare minutes to state that I have decided to “split” the Arduino system, well rather the PCB’s as I was simply trying to do to much on one PCB so what I have done is split the power supply onto one board, and as I am splitting it I have taken the opportunity to add a second regulator to the design for 3.3volt along with its associated smoothing capacitors so I can integrate 3.3v electronics into the system in the future if I want, besides I can then intergrate the powerboard design into other projects making the extra PCB’s I will purchase usefull as most places have a minimum run of 4 or 5, which means that for the once of projects its not paticuarly useful, but if I design it right the first time I can use the board on other projects as well. On this board as well will be the two OPAMP’s and the linear optocoupler to allow for the monitoring of the power via a plug in lead to the board, meaning that in total there will be 2 leads to the board, the first one carrying power (12VDC, 5VDC, 3.3VDC and ground) and the second one being the voltage monitoring.

I will release the designs for it once I have built it and tested it

SafeDuino – Part 03: The goalposts change

Ok, I admit it… feature creep has officially set in on this project.

After doing the basic designs and working out I needed the EtherMega (from Freetronics) for the SafeDuino project, and consequently purchased some (I say some as I keep changing the design) of the components I decided that it was a “waste” of a mega to only use the small number of I/O’s I needed (but more than I could get from an ethernet connected UNO), and this is where the feature creep began.

So, now what I have is more of an environmental monitor not only for the cabinet it was to maintain originally, but also for the room/building it is housed in, this will allow me to do differential monitoring for parts of the building vs the areas I am going to monitor/control individually.

So far I have determined, that beyond the original cabinet it was going to monitor, the following are going to be monitored;

  • The building itself, this is to allow for differential comparisons and fluctuations in temperature and humidity to see if the things I am putting in place to control humidity are in fact working
  • Two other cabinets, including one humidor, just because I can 😀
    • Turn on/off humidification/dehumidification equipment and fans to allow for circulation in the closed environments based upon readings
  • Possibility of wine/beer fridges
  • External temperature/humidity
  • Solar Radiation (for estimating solar panel power generation)
  • Background radiation, this is more of another because I can thing, being able to monitor radiation (Alpha, Beta, Gamma) in the background of the environment long-term will be useful in the future just to see the changes over time, I will be connecting it to one of the sensor networks that have popped up after the Fukushima accident
  • Internal and External light sensors, again to see how it affects temperature/humidity in the closed environments/building
  • Same goes for door/window openings

I am sure there is more to come, in fact I know there is, I have 40 odd pins to fill up :D.

In addition to these added features, I have decided to add some protection to the arduino itself through the use of optocouplers/optoisolators to isolate the external electronics from the device itself, where possible anyway, this will also take some of the current loading of the arduino board. So far I have confirmed that the 4N25 optocouplers work, and I have tested those which I have purchased to ensure they operate correctly.

I am still to get a few linear optocouplers for use the with the voltage divider to allow me to monitor the voltage in the battery system.

Considering ultimately that the EtherMega will be powered via POE (supplied by the switch, so a proper 801.11af regulator, which is being done to ensure monitoring will continue even if the batteries for the lights etc fail) there will be no load on the batteries apart from a few mA for sensors and alike for the most part, but I will be configuring the reed switches for example to be Normally Open (NO) so that there is no power going through them when they are not activated (apart from what is used by the resistors to keep a proper ground) I should be able to maintain this for a long period with just the batteries, and with a solar charger, I should be able to maintain this use of the system indefinitely.