Automatic Retracts For Your Drone

Introduction

Do you own a drone with a camera?  Have you ever taken footage with your camera that would look perfect, if only your landing gear were not in the frame.
Sample of landing gear in camera view

The solution; add retractable landing gear.  In this blog post I am going to show you how to set up a set of retractable landing gear.  Not only that, we are going to automate it's operation.

The Retracts

There are many different types of servoless retracts that you can buy.  You can buy the bare retract modules, the type with wheels for an RC plane or the type that I used with carbon fiber legs like this.
Drone retractable landing gearI bought this set off of ebay for the reasonable price of $32.29 US dollars.  The kit did come in pieces, so I did have to put them together once I got them, but it was pretty straight forward and easy.  once I got them assembled I had to find a way to attach them to my drone.  The drone I am attaching them to is a hexacopter with a 27.5 inch (707.39 mm) arm span from tip to tip of one of the long arms.  
Drone without retractsPart of my issue was that the side arms of the copter were swept slightly forward.  If I was just to mount the retracts perpendicular to the side arms, the gear, when in the downward position would be pigeon toed in toward the front.  Because of this, I wanted a mount that would keep the legs parallel when in the down position.  For this I used some creative 3D modeling and created this.
Retract mount CAD viewThis allowed me to keep the 15 or so degree sweep and have the legs parallel to each other.  Plus it fit around the square tubing used for the arm giving it a solid surface to mount to.  If there is interest in this retract mount I will post it on thingiverse.  Just send me an email and I will post it.  Here is a pic of the drone with the retracts mounted.
Drone with retracts mounted
You will notice that the base of the legs have foam on them.  I just used standard 1/2 inch pipe insulating foam that you can buy at your local hardware store.

The Automation

So now I have this set of retractable landing gear set up on the drone, how am I going to make them work?  I could do the old practice of setting them up to be controlled by a switch on my remote, but where is the fun in that.  Then I'd have to remember to flip the switch when I got in the air and flip it back when I wanted to land.  I found a video on youtube of a guy that built a cheap retract control using an arduino nano.  I thought that I would give it a go.  The only problem was that I didn't have a nano in my stockpile of parts, and the firmware that he had for it was specific to the nano and he didn't release the source code for me to compile it for a different module.  I had a couple pro micro boards in my parts bin, so I worked with that. 

The board is built using a BMP180 barometric pressure sensor which is used for measuring altitude.  Retract control board The board is then configured to retract the landing gear automatically when the drone reaches a set altitude, and then extends automatically when it is below that set altitude.  Being that the guy in the youtube video had not released the firmware source code for his unit, I took to the keyboard and wrote my own.  I have the source code posed on github for anyone interested.  The firmware can be configured with any terminal windo that can connect to a serial device such as the terminal in Mission Planner.  With the firmware loaded and in a terminal window just type "menu" to see a list of the options available.  When settings are changed, they are automatically saved and will be loaded on future restarts of the drone. 

The drone should be sitting on the ground or surface that you are going to launch from when powered on.  Once powered on, the firmware reads the current altitude and sets that as it's baseline measurement for determining when to retract and extend.  The default height for the firmware is 72 inches, or 6 feet.  Once the drone reaches the set height, the legs should automatically retract.  When the drone goes below the set height, the legs should extend down in preparation for landing.  The height that you set should take into account the normal rate of descent and the amount of time that it takes for your landing gear to fully extend.  A slower descent will allow you to set the retraction height lower.  One way to help prevent a hard landing when the legs aren't fully extended is to add a downward facing sonar module set up to slow the descent when close to the ground.

Conclusion

I hope you found this post interesting.  If you have any questions or comments, post them here or send me an email.  Happy flying.

Anti-Spam by CleanTalk review

Let me start by saying that this is my own personal opinion/review of this product.  I have to say that in the short trial period that I used the Anti-Spam by CleanTalk plugin for my WordPress website I have been very pleased.  I used to have to wade through 30 or more spam comments per day to decide if they were real or not and send them to my spam folder.  In the seven days that I have used it, it blocked 288 submissions from my website.  I did get a small handful (less than 5) in the seven days that I used it, but as I marked them as spam, the plugin added them to their list which as I understand it, increases the power for others.  

I fully recommend this product.  At $8 per year for one website for the service compared to the time that it saves is WELL worth the money.  That is less than a dollar a month.  If you run multiple websites, the price gets cheaper per site the more you have.  For me to give up one diet pepsi per month for this kind of protection, I can handle that.  

Visit https://cleantalk.org/help/cleantalk-spam-firewall for more details.  You can get a 7 day no obligation free trial to see for yourself.  You do not have to enter any credit card information to sign up for the trial, so what are you waiting for.

Heat bed connector tips

Introduction

If you own one of the popular Anet A8 3D printers, you have probably read about or experienced the dreaded burnt heat bed connector.  In this post I will talk about how and why this happens, and ways to fix or even prevent this before it becomes a problem.

Burnt heat bed connector

What is this and how does it happen

In the image seen above, the brown area on the side of the connector is heated burnt plastic.  This is caused from the metal connector inside the plastic housing getting hot.  Why does this get hot you ask?  The root cause of this problem is movement of the connector due to the wires not being secured.  As the printer is printing and moving forward and back, the wires are constantly moving from side to side.  This movement puts stress on the connectors inside the plastic housing as they are connected to the pin causing micro gaps between the connectors and the pins.  Because of these gaps the high current traveling through the connector arcs across these gaps.  Every time an arc happens, a small amount of oxidation builds up at the point where the arc happened.  As the connector continues to arc and the oxidation on the connector and pin builds up, this causes resistance.  With resistance and high current comes heat. The more the movement, the more arcing.  The more arcing the more oxidation buildup.  The more oxidation buildup the higher the resistance.  The higher the resistance, the more heat.  All this until the connector can't take it any more.  If it gets bad enough, this can start a fire.

3D printer fire

A fundamental cause of the problem

Heat bed connectorThe Anet A8 printer has a fundamental design flaw in the heat bed connector from the get go that can increase the chances of the connector heating up and burning out.  The connector used on the heat bed is a VHR-6N manufactured by JST.  The easiest is to buy a pre-made harness rather than the connector.  If you just buy the connector, then you have to have the proper crimper to attach the connectors.  There are not a lot of companies that sell a full harness that I have found.  They can be found on ebay though.  Just do a search for "JST VHR-6N harness".  You can usually get them in 1 or 2 foot lengths.  Next, if you look at the data sheet for this connector (http://www.jst-mfg.com/product/pdf/eng/eVH.pdf), it has a rating of 10 amps.  That is 10 amps per pin which is close to what the heat bed draws, actually a little less.  The heat bed has a resistance of around 1 ohm, and according to ohms law, current = voltage / resistance, so at 12 volts, the heat bed should draw approximately 12 amps. The connector has 6 pins, but the manufacturers of the Anet A8 decided to only use 4 of the 6 pins with their wiring.  The outer two pins are the power connections for the bed, and the middle two pins are for the heat bed thermistor.  Because of this, there is a potential 12 am draw on a pin rated for only 10 amps.  The ideal connection would be to use the outer TWO pins on each side, marked + + and - - on the image.  Using two wires for each spreads that 12 amps evenly over the 2 pins.  Therefore you get a current of 6 amps on each pin which is 4 amps less than what they are rated for which is MUCH safer.

How to fix the problem

I see SO MANY PEOPLE out there that say that the fix for this problem is to add a MOSFET to your power connections for your heat bed.  This is NOT the answer.  So you may ask, how do I fix this issue.  Fixing this issue requires addressing the two problems discussed here, motion of the wire causing arcing, and spreading the connection of the wires on the heat bed across both positive and both negative connector pins to even out the distribution of the current that the heat bed draws.

Heat bed strain reliefThe first one is easy to deal with, and that is with the use of strain relief on the wire preventing it from moving the connector.  This can be something as simple as using a binder clip to hold the wire to the bed, to a bit more complex using the Y axis cable chain mod.  Basically anything that can keep the wire from moving the connector around while printing should work.

The next is to modify or replace the heat bed connector.  One mod can be seen in the image above which uses spade connectors that will connect between the two positive and the two negative pins on the connector and using the stock wire.Replacement heat bed connector  Another option is to buy a replacement heat bed connector that has all four wires and connecting both positives and both negatives together at the heat bed connection point, be that at the main board or  mosfet if you have done such a mod.

Conclusion

I hope you found this information informative.  I wrote this in the hopes that it can help new Anet users prevent some of the issues that can arise, as well as helping users that have ran into these problems to figure out the best fix for their situation.  In any case, happy 3D printing and I hope you get years of use out of your Anet printer.

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Smart home vs an automated home

Smart v automated home

Introduction

In this article I’ll touch on the Internet Of Things (IOT) and what it is.  I will talk about, and show similarities and differences between a smart home versus an automated home.  I will talk about different home automation software packages and different ways to gear your IOT devices towards making your home more of a smart home.

Internet Of Things

You may have heard the terms IOT or IOE before and said, what the heck is that.  IOT stands for the Internet Of Things.  Similarily, IOE stands for the Internet Of Everything.  IOT and IOE,  in it’s broadest sense is the process of making the things that we use every day, in some way shape or form, connected to the internet.  These things have various sensors and control functions.  Being connected to the internet allows outside access to to the data and control that those sensors and controls provide.  IOT is a way of simplifying the world around you.  IDC, a market intelligence research firm, says that there are around 13 billion connected devices in use worldwide already.  Business Insider (BI) Intelligence projects 34 billion devices will be connected by 2020.

Home automation projects

X10 LogoOne aspect of IOT that is becoming more common is home automation.  Home automation is nothing new though.  My start into home automation began many years ago with X10.  I found it nice to be able to control devices remotely.  With their software called ActiveHome, I could also automate things with motion sensors and timers using a computer.  After using it for a bit, I found that there were things that I wanted to do that my X10 hardware could not.  Since then I have tried a number of different software packages, most of which fit in the realm of home automation platforms.Automation controllers  Some of these have included MisterHouse, Domoticz and most recently my VeraPlus controller.  I have another blog post talking about my home automation setup.  https://dan.bemowski.info/2017/06/11/my-home-automation-setup/

OSA smart homeOne project I was a part of that geared itself toward being more of a smart home system than an automated home system.  That project was called Open Source Automation, or OSA.  The features that drew me toward the system were it’s ability to integrate a number of different types of hardware into one system.  Another thing that drew me toward it was it’s focus towards being a smart home controller. When I was on the project, the smart home features were in their infancy, but moving forward.

Smart home vs automated home

So what is the difference between an automated house and a smart house.  The ability for you to turn devices on and off from your phone, and scheduling lights and other devices to turn on and off on different schedules, simply means that you have an automated home.  You may ask then, how is that different from a smart home.  A smart home adds other layers on to the automated home system giving it a new level of functionality.

The broadest aspect of a smart home is gathering lots of data.  Smart homes are made of many data gathering tools and sensors.  Gather more data and you can  make more intelligent decisions based on that data.  Another thing we’ll throw into the mix is objects.  These objects have many properties.  The properties of these objects, combined with data that your system has collected can now make smart decisions.  Now your system is gearing up to be a smart house.

One of the biggest pieces of data in all of this, and the most difficult to manage, is occupancy sensing.  A basic level of occupancy sensing is to put motion sensors in a room that will turn lights on and off.  However, the use of a motion sensor will only tell your system that one or more people occupy an area.  Now what if you could tell how many people were in that area.  To take that a step further, what if you could tell exactly who was in a particular area.  Now you can make smart decisions based on that added data.  

People objects

People iconPreviously we mentioned objects and their corresponding properties.  So lets say we defined a person as one of those objects.  We’ll define two “person” objects using myself (Dan) and my wife (Karen) as examples.  So let’s say Dan likes the temperature in a room to be 70° and he likes a lot of light in a room.  Two properties for Dan would then be “temp = 70°” and “lightLevel = 100%”.  Now Karen likes the temperature in a room to be 67° and have the lights a little dimmer, so her two properties would be “temp = 67°” and “lightLevel = 70%”.  Let’s combine this with motion sensing with person recognition.  You can now define your rule on your main controller to say:

If ( motion_sensed ) {
    if (furnace_mode == off ) {
        set furnace = on; //Turn the furnace on if someone is in the area
    }  
    set furnace_temp = temp; //Set the temperature to the users desired temp
    set lights = lightLevel ; //Set the lights to the users desired light level
    }
}

So with that, if I walk into the room and the furnace is off, it will set the temperature to 70° and turn the lights on to 100%.  If my wife walks in under the same scenario, The furnace will set itself to 67° and the lights will dim to 70%.

As you can see, the more data you can gather, the smarter, more informed decisions your automation controller can make based on that data.  Using this approach can save energy and improve the quality of life for the occupants.  You should now be able to tell the difference between a smart house and an automated house.

Conclusion

So to sum it up, an automated house gives you control of devices from an external source such as a smart phone and limited action from other sensors such as motion sensors.  A smart house makes it’s decisions using multiple factors and sensors.  Check out the ongoing discussion on this topic on the MySensors website https://forum.mysensors.org/topic/7814/a-smart-home-vs-an-automated-home/ .

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Temperature-humidity sensor

Temperature & Humidity

Description

This post will outline how I built some temperature-humidity sensors for my home automation setup to use in a couple rooms in my house.  I’ll explain some of the options I tried before coming to my final design.  I will also give you links to where you can purchase the parts and to download the 3D printer files for the enclosure.

Introduction

This originally started from an idea I had for my home automation setup to put a temperature and humidity sensor in my main bathroom.  The main reason for this was to help a small problem with occasional small mold spots on my ceiling.  This was most likely due to humidity in the bathroom.  When someone would take a shower, they would turn on the vent fan before showering, and then off shortly after.  The problem is that when the vent fan is shut off, there still may be excess humidity in the room that could eventually cause the mold.

The idea was that I could have a controller on the vent fan for the bathroom that would turn on when the humidity reached a certain level, and then would also turn off when below another level.  The two levels would factor in some hysteresis to the equation to prevent the fan from continually starting and stopping when the humidity is near a certain level.   By doing this, the humidity in the room would be dropped to a safe level before shutting off, thus preventing the mold problem.

The temperature-humidity sensor design ideas

So I needed to figure out everything I would need for the project.  My primary home automation setup revolves around MySensors nodes.  Those nodes talk to my Vera Plus automation controller.  I decided to make the temperature and humidity sensor a MySensors node.  The exhaust fan control, which I have yet to do, will be controlled by a converted Sonoff module.  For this article i’ll focus on the Temperature and humidity sensor. 

Below is a list of the things I needed to create the sensor.  The basic list was simple

  • A circuit board for the project.  
  • A micro-controller to control the sensor.
  • A temperature and humidity sensor.
  • Some kind of power source.
  • An enclosure to mount the sensor to the wall.

On to building the prototype

Easy/Newbie PCBFor the circuit board, I had a number of the MySensors Easy/Newbie circuit boards, so I thought that would be a good choice.  For that board I needed an Arduino Pro Mini, and an nRf24L01+ radio.  

Now I needed to choose a temperature-humidity sensor.  I had both some DHT11 and some DHT22 sensors.  The DHT22 is a higher resolution sensor, so I originally decided to try that one.  Through some testing with the DHT22 sensor I found that the power consumption was too high.  HDC1080 thumbnailI did some looking and found the HDC1080 sensor.  This sensor connects to the I2C bus and uses very low power.  It’s low power consumption made it ideal for use on a battery operated node.   By removing the regulator and power LED from the Pro Mini I was able to run this sensor for a week with no significant power drain on a set of 2 – AA batteries.

The last piece of the puzzle was an enclosure.  The enclosure had to be vented since I was measuring temperature and humidity.  It also needed to be able to hold a battery  or set of batteries.  I figured that I should find the battery box first, and then design the sensor enclosure around that and the PCB.  I settled on this one.

The enclosure design

I have dealt with temperature sensor enclosures before, so I had some ideas on what the enclosure should look like.  temperature-humidity wall boxI turned to OpenSCAD and came up with a basic design.  The box was vented, it had mounting tabs for the PCB and a place to hold the battery box.  temperature-humidity wall plateI decided to make it easy to remove from the wall if needed and made the wall plate with two tabs that the cover could lock on to. 

Since the creation of the first prototype wall box, I have done a couple revisions to the design.  This is what the final design looks like.temperature-humidity wall box V3
Version 3 of the wall box is highly configurable and can be adapted to other configurations if needed.  All versions of the wall box can be found on my thingiverse page https://www.thingiverse.com/thing:2186286

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RS485 communication techniques

RS485

Introduction

RS485 is a physical layer communication standard typically used in automation systems as a way for sensors and other devices to communicate to a central automation computer.  It is also used in computer system peripherals for data communication between devices.  A couple examples of this are the Small Computer Systems Interface, or SCSI-2 and SCSI-3 interfaces for hard disk drives.  Different systems use different protocols as their defined standards outlining the “language” they will use to communicate to each other.   In this short article I will discuss data communication using an RS485 serial bus and the best practices for an error free signal.

What is RS485?

RS485 has sometimes been referred to as a protocol, which it is not.   It is simply a communications interface wiring standard.  Unlike RS232 serial which is used for point to point serial communications, RS485 is a standard used for multi-point serial communications.  RS485 communication is typically done at half duplex using two wires  handling both transmit and receive.  Full duplex operation can be achieved using 4 wires depending on signal and speed needs.  Below is a diagram of an RS485 serial bus showing the master node and slave nodes.
RS485 Bus Diagram
As can be seen in the diagram, there is the two data lines, or differential pair, where the master and slaves connect, and at the end of the differential pair is a series of termination resistors.  Because the wires are a differential pair, the termination resistors are used to prevent reflections of the signal from back-feeding on to the line and causing collisions.  An RS485 network should only have termination resistors at the beginning and end of the transmission line.

The communication

Data transmitted on an RS485 bus can be heard by all nodes connected to that bus.  Because of this, a protocol is used to determine how that communication is managed.   The protocol must define a system for how data is transmitted, how a node knows that the data is meant for that node and how that node responds to the data it receives.  There have been a number of different protocol standards used in RS485 communication, with one of the most notable standards being the Modbus protocol.

RS485 interface types

RS485 USB Interface

There are many different types of RS485 interfaces on the market.  One is a USB type interface as seen on the left. This type will allow you to use a laptop or desktop PC as a master device, or a slave node on the network.  Another type such as the interfaces shown below are typically used to connect to a micro-controller such as an Arduino or a PICAXE, or small credit card size computers like the Raspberry PI or Beaglebone Black.  Interfaces such as the ones below typically come with the termination resistors integrated on to the board and may need to be removed if being used as slave nodes in the network.Microcontroller RS485 interfaces

RS485 bus setup

In an RS485 topology, the network is designed as one single line with multiple drops, or slave nodes.  As mentioned previously, termination resistors are put in place at both ends of the line to prevent signal reflection.  When termination resistors are not used, signal reflection can distort the signal on the line to the point of causing data loss or corruption.  These reflections are more noticeable on longer runs because the length of the pulse is long enough for the full pulse to make it to the far receiving end.  Once it reaches the end, it is then reflected back causing ghost signals that can differ in phase by the time it has ended.  On shorter cable runs, the the delay of the reflected signal is short enough that the distortion may not affect things because the phase difference will be negligible.
RS485 bus termination
Termination resistors should not be used at the slave nodes as this will cause unwanted signal attenuation.  With too much attenuation the signal may get lost completely.  Therefore, on node adapters where termination resistors are in place by default, such as the ones pictured above, you may need to remove them if they are not acting as the end node.

Conclusion

RS485 can be a good way of connecting automation devices where wired connection between devices is critical in preventing drops in signal.  Following these simple rules for connecting the bus, the signal transmission between devices should be quite reliable.

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Unseen door sensors

Door sensors

Unseen door sensors

NOTE: This is a post copied from my old website.  This content was posted back in 2012, but the idea is still a good relevant one.

I did some testing with a theory for a hidden door sensor.  I had a pile of magnetic reed switches and got to thinking.  Neodymium rare earth magnets are the strongest magnets you can get.  I had one that I pulled from an old hard drive that was very strong.  I connected my continuity tester to the switch and set it on top of my desk which is made of 3/4 inch press board.  I held the magnet under the desk top and was able to activate the reed switch with the magnet even 1/2 inch or more away from the bottom of the desk top.  This told me that it should be able to activate the switch through the frame of a door.  The distance from the hinged side of the door to where the magnet and reed switch are mounted will determine the sensitivity of the switch action.  The switch would be most sensitive at the furthest point from the hinged side.  Below is a diagram of the concept.

 

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The setup of my 1-Wire network

Introduction

DISCLAIMER:  This post was copied from my old web page and is a bit old.  Some information contained within this post may be out of date.
In my home automation setup, I wanted to be able to monitor temperature in various places around my house as well as outdoors.  I wanted a solution that was relatively cheap and easy to use.  My brother some time back had mentioned to me about something called 1-Wire.  He had used it up at his cabin to monitor temperature and electric usage through current sensing.  I did a bit of searching and found that it fit both of my needs, cheap and easy to set up.  So I figured I would document my setup here.

The 1-wire interface

1-wire adapterThe first thing I needed to run this was some type of 1-Wire computer interface.  After looking at options, I came across the DS9097U adapter on Ebay.  Unlike other 1-Wire adapters that had an RJ11 jack for connecting the sensors, this model had 2 – 3.5 mm headphone style jacks on it.  It did come with an adapter to connect the RJ11 style sensors if needed.  It looked like that adapter would fit the bill perfectly.  I ended up purchasing one for around $20.00 US from a china distributor on Ebay.

The sensors

The next thing I was going to need was some of the 1-Wire temperature sensors.  My brother had mentioned that he got all of his equipment from a company called Hobby Boards.  I checked their website and I could buy the bare temperature sensors for about $4.50, but they wanted $10.00 for shipping.  I decided to check Ebay.  I figured that if I could get the adapter cheap, I should be able to get the sensors cheap too.  I ended up finding another chinese distributor that sold the sensors in packs of 5 for around $7.00 shipped.  A pack of 5 of them from Hobby Boards would have been about $40.00 shipped, so I went for the Ebay deal (who wouldn’t at that price), so I bought a pack of 5 just to try things out.

The build

Now that I had all the parts, I needed to figure out how to wire things up.  Looking at the data sheet, I saw that there were 2 ways to wire these devices.  The first was using parasite power.  This is basically powering the device from power it grabs from the 1-wire network.

The other way was to use an external 5 volt power source.

So, if I was to use the external power source, how would I accomplish this.  I once again turned to Hobby Boards who had a how to section that outlined a wiring specification that used cat5 wire, and supplied a regulated 5 volts along with an unregulated 12-24 volts on the wire for use down the line for other devices.  The color scheme shown here is using the ISO T568A standard.  Most cat5 cables that you buy these days use the ISO T568B specification which is what I am using.  The only noticeable difference is that the orange and green wire pairs are reversed putting the color order at, white orange, orange, white green, etc… 

I figured using a documented wiring spec would be more reliable, mainly because it has been tested and used by others.  Not to mention if I wanted to add other devices from Hobby Boards, I can do it without having to re-wire things.

Now that I had a wiring specification planned out, I had to figure out the temperature sensor nodes.  Using the information from the DS18B20 data sheet, I devised a simple circuit that allowed me the option of using parasite power or external power.  Using a jumper on a 3 position header I was able to quickly switch between the 2 if needed.  In the schematic shown to the left, placing the header jumper across pins 2 and 3 will run the sensor on parasite power.  Conversely, by placing the jumper on pins 1 and 2, I could run it on the 5 volt external power.

Since the majority of the nodes were going to be in the house on walls, I wanted something that wasn’t going to look unsightly on the wall.  I ended up finding someone that was throwing out some old vented covered wall boxes.  I then put together a couple of these circuits on some perfboard.  I even made an etched board that although it turned out good took too much time.  The perfboard versions were much easier to do in the small quantity that I needed, and they worked just as well.  To the right is one of my perfboard sensors mounted on the wall plate ready to be installed.  I connected each one individually and used the software that came with the 1-Wire adapter to get the built in hardware address of each sensor and labeled each one.

The installation

Now that I had a few of these built, it was time to install them around my house.  To start, I installed one in the master bedroom, orne in the spare bedroom and one outside on the outer edge of my deck.  I wired these up with the cat5 wire just stripped and screwed to the terminal block using the blue pair and the solid orange wire.  Though  this works, my issue with it right now is that none of the connections pass the other wire pair signals down the line, like the 12-24 volt power.  For now, this is not an issue, but I do have a plan for fixing it which I still need to implement. The idea is to use an RJ45 splitter adapter similar to the one shown to the left.  By crimping modular plugs to the ends of each cable coming to the temp sensors and plugging them into the 2 jacks on the adapter, this will pass all signal and power lines through. I can then clip the wire that comes off of the adapter and use it to connect to the temp sensor or whatever other sensor I try to install.

The only other hurdle to attack in this project is to get things set up in my automation software.  This was insanely easy.  I installed the 1-Wire plugin for OSA and after plugging the sensors into the adapter, OSA sent a 1-wire search ROM signal which automatically detects any sensors attached to the 1-Wire bus.  OSA then automatically added these as objects to the system.  All I needed to do then is to add them to my floorplan view and make use of them in the system.

I started with the outdoor sensor.  Looking at my RCS thermostat a while back, I noticed that it had an option for displaying the outdoor temperature on the wall display keypad.  Since I wrote the OSA plugin for it, I simply added an option for taking the temperature value from any other OSA object and sending it to the thermostat.  Now if I want to know the temperature outside, I just look at my thermostat.

I wanted to do more than just use these to display the temperature on a wall display.  My next thing to tackle was to use the value from my master bedroom sensor to aid in controlling a booster fan that I have attached to my furnace.  The booster fan was originally set up to come on any time the furnace or central air turned on.  I thought that this was a waste of energy, so I set up a script to say if it is between 9:00 PM and 1:00 AM, and the temperature in the room is below 68° in the room when the furnace kicks in, then turn on the booster fan.  This is so that the room is warmed up a bit when we go to bed.  I will do something similar for the summer months and using the air conditioner.  Now I have some real world energy saving with the system.  Though not much, i’d suspect, it is something.

I have recently installed two of these in my bar/man cave area in my basement.  The room is very long with a fireplace at one end.  My plan is to monitor both temp sensors and when the one closest to the fireplace shows a temp that is 3 or more degrees higher than the one on the other end of the room, it would turn on a fan to circulate the air in the room.  The fan would then stay on until the temperature normalized throughout the basement.

One more thing that I plan on doing which I have not yet set up is to put a system in place for humidity control in my bathroom.  The idea is to install a 1-Wire temperature and humidity sensor in the bathroom.  I will then install a controller on my vent fan that I can turn on when the humidity gets too high.  The fan would then stay on long enough for the humidity to get to a safe level.  The idea behind this is to control mold and mildew buildup in the bathroom.

Conclusion

There are many other uses for 1-Wire in a home automation setup.  Implemented correctly, many of these can save you time money and cleanup costs.  I have not even scratched the surface of things I can do with this, and I plan to do a lot more over time.

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Fix an oozing or leaking heat block

 Fixing an oozing or leaking heat block

Oozing heat blockIf you have done 3D printing, you may have experienced the oozing or leaking heat block problem.  This is where you have filament oozing from the heat block on either the top side by the throat tube, the bottom side by the nozzle or both.  This plastic will start to melt and drip down on your prints, and over time will burn on to your heat block leaving a big mess.  In this section I will discuss why this happens and how you can fix it.

 Why does this happen?

Incorrect block assemblyYou are probably wondering how this happened in the first place.  The main reason is that the heat block assembly became loose at some point.  This may be from movement and vibration when printing, or maybe you had to work on the assembly at some point to clean it or something else.  In the illustration on the right you see that there is a gap between the throat tube and nozzle inside the heat block.  This gap is what allows the heated filament to ooze out.  The heated plastic will be forced through the threads of the throat tube and possibly the nozzle and start pooling up at the top and bottom of the block.  If left long enough, the plastic will run down the side of the heat block and drip onto your nice print.

Now you are wondering, how can there be a gap there?  You say to yourself, I tightened the nozzle in when I re-assembled it, there can’t be a gap.  There is something you need to understand about metal.  When it is heated, it expands.  When a metal ring is heated, that expansion will be outwards.  If the throat tube and nozzle are not tightened together enough, the expansion of the block can cause this gap.  

How can I fix this?

So now you are wondering, is this something I can fix, or do I need to buy a new heat block assembly. There is a good chance you can fix this. The main thing is to tighten things when the block is heated and the metal is expanded during reassembly. This will reduce the chance of that gap forming the next time it is heated.

Heat block partsSince your heat block was leaking, you should first disassemble it and clean it.  Clean parts  reduce the chance of leaking in the future.  Remove your heat block assembly from the extruder carriage and set your printer to preheat.  preheating for ABS is probably the best as it will get your heat block to around 240 C (464 F) making things easier to clean.  With pliers holding the heat block, use a wrench or another set of pliers to remove the nozzle.  Once that is removed, your throat tube should come out easily.  Be VERY careful as the parts are extremely hot.  Use a wire brush to clean away any plastic from the throat tube, heat block and nozzle.  You may need to re-heat the parts to clean them good.  Once cleaned, you can begin to put it all back together.

Correct heat block assemblyThese first steps are easier to do when the parts are cool and you can use your hands to fit them together.  The proper way to assemble the heat block is to first thread the nozzle into the heat block, and once it is in all the way, back it off 2 turns.  Next, thread the throat tube in until you feel it hit the end of the nozzle threads.  DO NOT use pliers on the throat tube.  With the throat tube in all the way, grab the heat block with a pair of pliers and use a wrench to tighten the nozzle in place.  Once that is all together, heat up the heat block to temperature while holding it with the pliers.  This can be done with the heater on the printer, or the burner on your stove.  Don’t use a torch or it may get too hot.  Once heated, tighten the nozzle a bit more.  This will ensure that the gap between the throat tube and the nozzle will be closed not letting the filament ooze out.  In the illustration above, you will notice that after assembly, the nozzle is still not tight against the heat block.  This will allow you to tighten it again if you need to.  One more thing to note.  Do not put a nut on the throat tube and tighten it to the heat block.  This can cause more issues.  

Now you can re-assemble the extruder assembly.  Correct nut assemblyUse the nut on the throat tube to tighten the extruder assembly to the carriage to prevent the heat block assembly from spinning when printing.  Incorrect nut assemblyBe careful not to over-tighten the nut as you can easily break the throat tube.

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Adding HVAC overlays to MisterHouse

Introduction

DISCLAIMER: This is an old topic that I migrated from my old website due to the traffic it used to get.  I no longer use MisterHouse for my automation, so I will not be able to answer any questions regarding this topic.  Some of this information may be out of date, but may still work.

indoor temperatures graph

For some time now I have been using the MisterHouse automation software with my Raspberry Pi as my main automation software.  One of the features that I use is the weather data from the internet_weather.pl common code module.  I also have an RCS-TR40 RS485 thermostat and 7 one-wire temperature sensors throughout the house that I use with this setup also.  The weather module has a graphing feature that allows me to graph the indoor temperatures from my one-wire sensors.  A sample of this is shown to the right.  Though this was a nice feature, there was somehting missing.  I wanted a visual representation of my HVAC operation overlayed on the graph.  I saw a perfect example of what I was looking for on Marc Merlin’s blog site marc.merlins.org/perso/homeha/2009-12.html.  About 1/4 of the way down the page you will see the 2 graphs.  Marc uses cacti with RRD to get his results, but I was using a module in MisterHouse that did not have this functionality.  This post shows the steps I took to modify the code in the weather module to be able to do this.

The Code Modification for HVAC Overlays

Before performing any of the steps described here, it is always a good idea to make backups of the files that you are modifying in the event that you need to revert back.  With that said, let’s proceed.

The main file that you will need to modify is the weather_rrd_update_graphs file located in the MisterHouse/bin folder of your installation.  When I made the modifications to my setup, I had to start a new RRD database file because of the way that I modified the file.  I am going to show you how to do this in a way that SHOULD NOT affect your current RRD database.

The first step is to locate the section of code that defines the default color codes for the graphs.  In my file, this started at line 44.  Depending on the number of HVAC zones and whether you want to show heating, cooling or both for these zones, this will determine the number of tempspares that you will want to sacrifice for this.  In my setup I only have single zone heating and cooling, so I would only need to hijack $tempspare9 and $tempspare10.  The default color codes used for 9 and 10 are “66FFFF” and “0000CC” respectively.  These will need to be changed.  I used “FF6F7D88” (9) for the heating color, and “6F87FF88” (10) for the cooling color.  One thing you will notice that is different with these 2 values is that they are longer than the original values with the added “88” at the end of each. This is very important as the last 2 hex values are the transparency values.  This is what allows the HVAC color bars to be overlayed over thetemperature line graphs and still have them visible.

The next part is a bit tricky.  You will need to remove the tempspare RRD DEFinitions for whatever $tempspares you are using for this.  In my setup I would remove tempspare9 and tempspare 10 DEFs.  For each tempspare, you will need to remove 6 lines of code.

1 .\”DEF:mintempspare9=$RRD:tempspare9:MIN\”,
2 .($weather_uom_temp eq C ? \”CDEF:fmintempspare9=mintempspare9,32,-,5,9,/,*\”, : \”CDEF:fmintempspare9=mintempspare9\”,)
3 .\”DEF:maxtempspare9=$RRD:tempspare9:MAX\”,
4 .($weather_uom_temp eq C ? \”CDEF:fmaxtempspare9=maxtempspare9,32,-,5,9,/,*\”, : \”CDEF:fmaxtempspare9=maxtempspare9\”,)
5 .\”DEF:tempspare9=$RRD:tempspare9:AVERAGE\”,
6 .($weather_uom_temp eq C ? \”CDEF:ftempspare9=tempspare9,32,-,5,9,/,*\”, : \”CDEF:ftempspare9=tempspare9\”,)

Now, where you deleted these lines of code, you will add 2 lines for each tempspare you are replacing.

1
.“\”DEF:tempspare9=$RRD:tempspare9:AVERAGE\”,”
2 .“\”CDEF:ftempspare9=tempspare9,1,EQ,INF,UNKN,IF\”,”

Next, you will need to change the LINE2 definitions for your tempspares to AREA plots.  Find the following lines:
. ($sensor_names{tempspare9} ? “\”LINE2:… :”)

Remove the “LINE2” and “GPRINT” lines from each and replace with this:

“\”AREA:ftempspare9#${colortempspare9}:” . sprintf(“%-${max}s”,$sensor_names{tempspare9}) . “\”,”

For the last code modification, you need to edit the weather_rrd_update.pl file in “misterhouse/code/common/”.  Look for this block of code:

if($config_parms{weather_uom_temp} eq ‘C’) {
grep { $_=convert_c2f($_) unless $_ eq ‘U’ } ($rrd_TempOutdoor, $rrd_TempIndoor,
$rrd_TempSpare1, $rrd_TempSpare2, $rrd_TempSpare3, $rrd_TempSpare4,
$rrd_TempSpare5, $rrd_TempSpare6, $rrd_TempSpare7, $rrd_TempSpare8,
$rrd_TempSpare9, $rrd_TempSpare10, $rrd_DewOutdoor, $rrd_DewIndoor,
$rrd_DewSpare1, $rrd_DewSpare2, $rrd_DewSpare3, $rrd_TempOutdoorApparent
);
}

You will need to remove all references to TempSpareXX that you are converting.  If not done, this could prevent the HVAC bars from showing up if you have your user configuration “weather_uom_temp” set to “C”elsius.

HVAC overlays user code additions

Now you need to define things in your user code.  This will vary for each setup as thermostats and/or ways of identifying that the furnace or AC is on are done differently in each setup.  This is basically how I have it set up in my user code:

# Define the weather hash’s initial starting HVAC values
if ($Startup or $Reload) {
    $Weather{TempSpare9}  = int(0);
    $Weather{TempSpare10} = int(0);
}

#### Now, if your furnace is on tempspare 9, the code will be something like this: ####
if ($RCS_current_state eq ‘heat’) {
# Tell the weather hash that the furnace is on
$Weather{TempSpare9} = int(1);
} else {
# Tell the weather hash that the furnace is off
$Weather{TempSpare9} = int(0);
}

Last, you can tweak your setup in your mh.private.ini file adding your own sensor names for each tempspare that you set up.  You can also tweak the colors of your displayed bars from here the same as your other sensors.  Remember though, if you change color values in your mh.private.ini file, you NEED to add the transparency value to each color.  I found 88 to be a good transparency value for me, but your situation may differ.

Below is a sample output of my setup with the furnace overlays in place.

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