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Home automation over ethernet
The home automation over IP controller

Software

Right now the micro controller board with the Atmega168 can read analog inputs, switch relays and dim LEDs using pulse width modulation. However no logical decisions are made by the micro controller.

To do the logics I made a client and server application with Java that’s able to run JavaScript files in a script engine. The Java application retrieves the values from the micro controllers, executes the JavaScript and sends the updated values back to the micro controllers. It acts like some kind of soft PLC, running on a simple language like JavaScript.

Because the JavaScript based soft PLC has no GUI I integrated an extra webserver in it. Now it’s possible to create fancy interfaces with Adobe Flash or any other development tool that’s able to get and send data over HTTP.

A complete cycle is as follows:

1. retrieve IO status from micro controllers
2. execute script
3. retrieve modified IO status from script engine and put it in the IO buffer
4. apply modifications received by the server in IO buffer
5. flush the buffer to the micro controllers
6. goto step 1…

To avoid to much load on the network a cycle is only ran once every 200ms. For industrial purposes this could be to slow but for switching on and of lights in your house this is fast enough. When pushing a button in a Flash movie the delay is barely noticed.

Hardware

Beside the point that the modules will not be build in to a housing that can be mounted on a DIN rail there are no changes on the hardware part.

Can I get the source and schematics from this project?

At the moment, no. It might get open source one day, it might be not.

Het Digicorder probleem

Veel digitale kijkers die gebruik maken van de Digicorder van Telenet ondervinden na enkele jaren problemen. Deze gaan van af en toe een melding dat de stekker uitgetrokken moet worden om alle functionaliteiten te herstellen tot het continu herstarten van de Digicorder. De garantietermijn van de Digicorder bedraagt 2 jaar en die garantietermijn blijkt net iets korter te zijn dan de levenstermijn ervan. Wat weinig mensen weten is dat je voor nog geen 3 euro de Digicorder zelf kan herstellen.

De oorzaak van de problemen

Hoewel je zou kunnen denken dat de oorzaak aan de software ligt is dit veelal niet het geval. De eerste firmware versies van de Digicorder waren niet de beste maar tegenwoordig is de software behoorlijk stabiel. Waar het dan wel fout loopt bij de Digicorder is de hardware.

Na het openschroeven van de Digicorder wordt het probleem meteen duidelijk. Zeven condensatoren die bol staan of zelfs uitgelopen zijn.

Overzicht digicorder

Bolle en lekkende elco

De oplossing

Gezien het probleem ligt de oplossing voor de hand. Vervang de zeven onder gedimensioneerde elco’s door nieuwe van een hogere spanning.

De defecte elco’s zijn allen van het type 470µF/16V. De nieuwe condensatoren zijn eveneens 470µF maar dan 25V.

Benodigdheden:

• Defecte Digicorder
• 7 elco’s 470µF/25V
• Kruis schroevendraaier
• Soldeerbout
• Soldeertin

Begin met het openen van de behuizing. Hiervoor moet je 8 schroeven losdraaien. Het deksel schuif je dan een beetje naar achteren zodat je het eenvoudig kan verwijderen.

De condensatoren die we gaan vervangen bevinden zich op de grootste printplaat in de Digicorder. Aan de voorkant, naast de harde schijf, zie je 7 identieke twart/gouden condensatoren van 470µF/16V. Als deze bol staan of als ze lekken aan de bovenkant zit je met het probleem waar deze tutorial een oplossing voor biedt. Verder lezen is de boodschap!

Om met de soldeerbout aan de condensatoren te geraken moet de printplaat uit de Digicorder verwijderd worden. Als eerste moet het kleine zwevende printplaatje dat de houder bevat voor de smartcard los gemaakt worden.

Zwevende printplaat smartcard

Om deze printplaat te verwijderen maak je de twee schroeven aan de zijkant los. Haal ook de smartcard uit het slot.

Zwevende printplaat weg

Om voldoende ruimte te hebben om de twee printplaten die op de onderkant van de Digicorder liggen uit elkaar te halen moeten ze beide losgeschroefd worden. De kleine printplaat zit vast met 3 schroeven, de grote (met de elco’s) met 5. Vergeet ook de schroef aan de achterkant niet. Deze zit in de audio connector.

Niet te vergeten schroef

Om nog wat extra bewegingsvrijheid te geven aan de printplaten maak je ook best één van de schroeven van de harde schrijf los. Ook de blauwe geluidsdemper (jaja, die zitten er wel degelijk in) mag eruit.

Plaats maken

Maak ook alle connectoren los. Ook de voeding van de harde schijf, deze vertrekt immers van de printplaat die we uit de Digicorder gaan halen.

Connectoren los

Nu zouden de printplaten voldoende moeten kunnen schuiven om de aansluitingen die zich aan de achterkant van de Digicorder bevinden naar binnen te schuiven. Waarna de twee printplaten ook uit elkaar geschoven kunnen worden. De twee printplaten zijn gescheiden door middel van een stuk rechtopstaand plastiek.

Aansluitingen naar binnen geschoven

Printplaat losmaken

Losgemaakte printplaat

Nu de printplaat uit de Digicorder is kunnen de condensatoren los gesoldeerd worden. Vermits de printplaat loodvrij gesoldeerd is moet je zeker zien dat je soldeerbout warm genoeg staat. Als je de benen van de condensator warm maakt en terwijl aan de andere kant aan de condensator trekt met een klein tangetje gaat het los solderen behoorlijk vlot.

Desolderen elco's

Vervang de condensatoren door de nieuwe, lettend op de polariteit.

Elco 's vervangen

Als de zeven condensatoren vervangen zijn kan je je Digicorder weer in elkaar schroeven. Sluit alle connectoren weer aan en plaats ook de smartcard terug in het slot. Nu alles weer in elkaar zit zoals het hoort sluit je de Digicorder aan op je TV en zet je hem onder spanning.

Nieuwe condensatoren in digicorder

Gemaakte digicorder

Om met een propere lei te starten kan je ook een factory reset met verlies van data doen. Huisje -> instellingen -> Digibox/Digicorder -> Systeem instellingen -> Instellingen resetten.  Je Digicorder zal nu herstarten. Geef je netwerk en regio code in (zie boekje Digicorder). Laat nu je Digicorder even met rust. De software zal geüpdatet worden en de tvgids wordt gedownload. Als dit allemaal achter de rug is trek je je stroomkabel nog eens uit en steek je hem weer in. Veel kans dat je nu weer even verder kan met je Digicorder.

Conclusie

Veel mensen denken onterecht dat hun Digicorder voor de vuilbak is als hij meer en meer irritante kuren krijgt. Dit is ook wat men aanraadt bij de Telenet helpdesk. Telenet heeft er immers voordeel bij als je overschakelt van je gekochte toestel op een huur Digicorder.

Hoewel er enige handigheid en tijd benodigd is om deze reparatie tot een goed einde te brengen is ze niet onoverkomelijk. En zeker niet duur. Voor minder dan 3 euro heb je weer een werkende Digicorder. Het proberen waard als de garantietermijn verstreken is!

Include the Atmega watchdog functions:

Enable the watchdog timer:

Super loop:

Restart the microcontroller:

This an easy and effective way to reset the controller.

Unfortunately the tcp/ip stack has some internal loops that keep the system busy when the network cable is disconnected. Because the watchdog timer is only reseted at the beginning of the super loop the watchdog flows over, again and again. When the micro controller boots the settings are read/written from and to the eeprom. With a maximum of 100.000 write cycles for eeprom leaving it powered for a whole day wasn’t a good move. Time to order a new micro controller, again some learning money spend

To make it possible to mount the controller in a common electric cabinet it will be housed in a DIN Rail mountable enclosure.

DIN Rail housing

To bring the micro controller outputs to the exterior I made a PCB using the toner transfer method.

PCB for connectors

After soldering the connectors on the PCB and wiring the micro controller board to the connector board everything is mounted in the enclosure. At the moment the PCB’s are not yet fixed in the enclosure.

Controller mounted on rail

Currently the firmware supports the change of some basic settings like IP, MAC and IO port direction. 12 IO ports are available on the connectors. Four of them can be used as analog input, they can all be configured as digital input or output. To make flashing the firmware possible while the micro controller is in it’s housing the ISP port is also available on the connectors.

The current version of the computer software can be used to set digital outputs and read analog inputs.

Computer software screenshot

Because using a mouse or keyboard isn’t fancy enough for home automation a 7″ touch screen will be connected to the computer.

The next step will be attaching a relay board so the controller can be used to switch lights or other appliances.

Not being sure about the quality of the final result I designed the PCB with wide paths. This way a lack of precision shouldn’t be a big problem.

PCB Design

What you we need:

• a PCB design (obvious)
• a blank board (without photosensitive layer)
• magazine paper
• a laser printer
• an iron, preferably without steaming capabilities
• personal protection against chemicals (gloves, safety glasses and eventually a lab coat)
• glass or plastic bowl (never use a metallic bowl as etchant container!)
• etchant: HCl, H₂0₂ and H₂0
• thinner (acetone)

Step 1: Printing the PCB design

To print the design you need a laser printer (a copier should do the job too). An inkjet printed will NOT work. Common printer paper will work but to make the process easier paper with a glossy layer is recommended. You can use expensive photo paper but magazine paper will work too. Since the magazines a printed using ink the content will not transfer. Still I discourage the use of pages with pictures, look for text on a white background.

Before printing make sure your not using an almost empty toner and change the printer settings to the darkest possible mode (avoid toner-saving-eco-modes).

Step 2: Transferring the design to the board

Cut the blank PCB to the required size. To ease the alignment cut the paper with the design on 3 of the 4 sides to the PCB size. Keep 1 side uncut to make it possible to hold the paper without having to put the hot iron on your hand.

Ironing can be done on a piece of wood. Set the iron as hot as possible.

Iron used for toner transfer

Align the paper on the board  (toner side on the copper side of the board) and put the iron on the paper. Don’t move the iron the first 10 seconds to avoid moving the paper. Next, keep on ironing until the paper becomes brown. Make sure to iron all spots. After the ironing the paper will stick to the PCB.

Ironed PCB board

Step 3: Removing the paper

Now it’s time to get rid of the paper. Put the board in a boil of ho water. After a while the paper can be removed from the board leaving the toner on the copper.

After the toner transfer

If some paper sticks to the toner that’s no problem but make sure the paper is removed on the places without toner. Especially take a look at the places where you’ll drill the holes later on. If you let the board dry for a while the spots with paper will become white and very visible.

Step 4: Etching

WARNING: THIS STEP INVOLVES DANGEROUS CHEMICALS. BE CAREFUL AND READ THE LABELS ON THE BOTTLES OF CHEMICALS BEFORE USING THEM. USE PERSONAL PROTECTION!

Use a plastic of glass boil for the etchant. For the mixture I use this proportions: 90/8/2  for respectively H₂0/HCl/H₂O₂.

Since the chemicals don’t come in 100% solutions some calculations need to be done before mixing. I have a 29% HCl solution and a 3% H₂O₂ solution.  For 150ml of etchant I used 9ml H₂O, 41ml HCl and 100ml H₂O₂. If you stored the etchant for a while the will be a lack of oxigen. You can revive the solution adding H₂O₂ or using a bubble machine for fishbowls.

First add the water, next the acid and finish with the peroxide. Mix it using a plastic or glass spoon.

Gently drop the PCB with the toner on it in the etchant. Move it around to fasten the etching. After a few minutes the copper will dissolve and the etchant will become green. If all the copper is gone take the board out of the etchant and clean it with a lot of water (not in a metal sink…).

Etching a PCB

Adding some oxigen

Step 5: Removing the toner

Use a thinner like acetone to remove the toner from the copper.

Removing the toner

Cleaned PCB

Step 6: Prepare the PCB for population

After removing the toner it’s time to drill the holes and eventually protect the copper. Using a drill stand making the holes goes pretty fast. Especially when you etched the copper away. Aligning the drill will be very easy.

Now the board is finished it’s time to populate it and solder the parts…

Final result - Heating the oven

After doing a lot of research (read googling) I had build my own brick oven in my head and it was time to build it in real bricks. Since I didn’t make detailed plans or calculations I’ll just provide you the pictures. If you’re going to build a brick oven make sure it’s unique, don’t stick to a plan, that makes it even more special! And now, the pictures…

Foundations

Oven mouth

The oven is build into the wall of a separate building (not the actual house). This makes sure pizza parties will not be disturbed by rain!

Surrounding wall

Surrounding building

After the foundations dried the actual building could start. The arcs are build next to each other, not the strongest solution but easier. To build the arcs I made a wooden arc. I remove it right after putting the bricks in place. If you would let the lime dry the arc would break while removing the piece of wood.

First arc of the oven build

The wooden arc

One arc to go

All arcs are in place

After the inner oven was ready the chimney could be build. The connection was build with bricks, for the chimney stainless steel piping was used.

To protect the oven I build a wall around it. The space between the oven and the outer wall was filled with insulation. A simple roof was made of ‘betonplex’ some kind of waterproof plywood.

Outer wall

Insulation

The roof

Chimney trough the roof

After the oven dried for some weeks it was time to use it. About 40 minutes of fire is enough to burn the oven clean. A gray ceiling means the bricks are hot enough to start baking. Leaving it burn another 20 minutes makes sure the floor contains enough heat to make a pizza.

Heating the oven

Making pizza

Ready after 3-5 minutes

I’ve been writing some basic software for the microcontroller making it possible to switch leds on and off and change the IP and MAC address of the modules. Also on the hardware part some decisions have been made. As mentioned in the previous post the modules will be mounted on a DIN rail. The microcontroller will have it’s own housing. Outputs and inputs will have a separate housing making it possible to create different configurations.

For the creation of the circuit boards the “Toner Transfer” method will be used. This is a cheap and accurate method to create prototypes. When I start creating the PCB’s I will explain this method in detail.

The software running on the server will not be written in VB.net but in Java since I want to leave the option for Linux as operating system open. Below you find a screenshot of the main screen. This is really an early development version, but it gives an idea.

The next step, something for tomorrow, will be ordering some electric components to create the prototype modules. To be continued.=;;

The programming cable is a printer port cable (parallel, LPT) with some resistors to protect the port. I don’t use optical isolation, it’s a direct connection. This brings some risks but is cheap, very cheap.

To make the programmer I used an printer old cable, and soldered resistors on the end as follows:

All resistors are 220R. This cheap AVR programmer works great. To send the programs to the AVR’s memory I use Ponyprog, a free tool compatible with the programming cable.

On my job I use ‘Industrial Ethernet’ everyday. It’s like your home LAN, but with more expensive switches and, in general, green wires and fancy connectors. The principles are the same, but for security reasons it’s separated from the office LAN. For home automation purposes it’s not necessary to separate the networks, actually it’s better to have only one network. That way I’ll be able to control the appliances from my computer.

My user requirements:

• Create a micro controller based module that ’speaks’ Ethernet.
• Make expansion modules to add relays, dimmers and inputs to the CPU.
• A user interface (VB.net and/or web based) to control the modules
• A computer service handling the logics (for time based switching etc.)
• …

To create the CPU module I’ll use a webserver board from http://tuxgraphics.org/, when the basics are programmed I’ll go on developping the hardware.

As enclosure for the modules I will use DIN-rail housings. This will not be the first concern, but size WILL matter while developping the printed circuit boards.

Things to do:

• Find the right programming and development tools
• Design PCB’s (probably with EAGLE)
• Make the PCB’s

The first two points on the short time to-do list are clear. The last one, the production of the circuit board, I’m not yet sure about. I never made a circuit board before. Will I use my CNC router do isolate the paths, make a UV box and use boards with a light sensitive layer or just find a company to produce the boards? I don’t know yet, suggestions are appreciated…