While programming a micro controller for the home automation over IP project there’s a lot of trial and error involved. To make it possible to reboot the micro controller remotely by software I was experimenting with an infinite loop without resetting the watchdog timer.
Making Printed Circuit Boards - Toner Transfer
For the home automation over IP project I needed a fast and easy method for creating printed circuit boards (PCB). After some research the “toner transfer method” seemed a solution to give a try.
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)
Home automation over ethernet - update
It has been a while since I announced the home automation over ethernet project. It’s time to make some progress!
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.=;;
Cheap AVR programmer
For my Home automation over Ethernet project I’m using an AVR micro controller. Several companies offer in system programmers for these controllers. Since I don’t need in system debugging a simple programmer will be enough form me.
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.
Home automation over Ethernet
A lot of houses are equipped with a wired Ethernet LAN. So why install an extra network just to turn on and of a light bulb or dim a light? Wouldn’t it be possible to use an ordinary Ethernet connection to control our home appliances?
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…
Home made CNC router
Techible.net engraved with CNC router
Ever wanted to cut some wood with very, I mean VERY high precision? Or just want to do some cool engraving? I have what you need. A home made CNC (Computer Numeric Controlled) router.
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