I recently created a printed circuit board for a raspberry PI design i’m working on. By the past, when I did such things, the cost to make it was not accessible for a home made design. In 10 years things have change a lot and now, you can do it for less than 100€ for a 10×10 two layer board. 4 layer is also something accessible.
I want to share with you this experience, because, I had a good and an bad experience to share.
You can imagine a lot of use cases for a such thing : a pen able to create electrical conductivity over ink. The one I found really interesting this morning is to make electronic a fun activity for my daughter. That’s the reason why I backed on this product.
This is a kickstarter project accessible for a couple of euros. I let you have a look to the project itself here .
Galileo is an Intel platform compatible with arduino ; more of that it is an embedded Pentium class platform. With 400MHz and 800mA and 55€ with Ethernet but no video out, I’m not totally sure this platform provides a real new thing in the embedded world.
By the way, it have some interesting advantages :
I let you have your own advice, to take a look to the detailed description here and buy it here (actually 9w delay)
After mixing different source of information, I was able to decode some Oregon Scientific sensors to get Temperature and Humidity indication, over the air, on 433.92MHz, with a Raspberry PI system. This article gives some details of this adventure …
You follow this implementation at your own risk…
If you are interrested in this article, you could also take a look here where you can find a RF433 shield and the associated code
After having test some receiver, naturally, I’ve tested some transmitters, the objective is the same : get the best coverage in the same condition : I would say poor conditions. Lots of wires going every where and an antenna make with a simple 17.3cm wire. As expected, results vary regarding the emitter used. Reed more to get details.
I’ve just done some test on different RF433 receivers, from the classical really low cost system to some more expensive systems. The test environment was always the same : a dirty test board with lots of wire connections everywhere and an antenna made with a 17.3 cm wire. The conditions are poor but identical.
Then I move around my house and activate my alarm detector one after one and check if the system received it. Some detector are same floor, 1 floor or 2 floors distance, some are behind walls, distance vary from 5 to 20 meters in house.
The following results are the number of message received by the different receivers in this context. More you see, better it is.
I some may mentioned, I was at Oracle OpenWorld conference last week. The main points I retained regarding my point of interest are listed in the following prezi :
http://prezi.com/c1vlmudi2dh2/?utm_campaign=share&utm_medium=copy
I start using mosquitto in a C++ program and I think documentation could be a little bit improved by some examples. To use mosquitto, there is a mosquittopp class acting as a wrapper on top of the mosquitto lib. Basically to create your own program you have to herit from that one and it is easy then.
Mosquitto lib can be managed as a thread or directly by calling the different sub function. In my point of view the thread approach is the better as otherwize you have to manage connection / disconnection manually. Mosquitto lib is then event managed, so you can subscribe to the callback event by surcharging the existing function.
Here is an exemple for a program just needing to publish messages to a broker.