A second video : this time about “life coding”. They are technics based on reverse engineering to understand how life and DNA is working to create robots ; even if all of this is more biology than computers I was really touched by the Xavier Duportet talk about these technics and what he is doing.
For these reasons, it is the topic of my second youtube video (as the first on it is in French).
Enjoy !
To tell you the full story, I was working on a 3d object I want to reproduce. The initial model is a 10cm object. I’ve got a 3D scan of this object and now I want to make a mold to reproduce it with a smaller size (3cm). All should be simple as even my printer software have a resize option.
The problem started when once resized the height of the object has became too small and the precision of the printer does not allow to have a good result. For my need it was not really important to preserve proportion on the Z axis. So I was looking for a tool able to resize an object with a different setting factor for each of the axis.
This tool exists and more over it is really useful for any STL manipulation (at least you need to be a coder) : its name is OpenSCAD. This tool is a programming language for 3D object allowing different object transformation and creation.
For my need to scale X & Y with a 0.4 factor and Z with a 0.6 factor, the following code was the solution :
scale([0.4, 0.4, 0.6]) import("Moule.stl", convexity=3);
You then just have to export as STL by clicking on STL icon and you have the result. Sounds nice, isn’t it ?!?
A new try for this website : my first video post !!
The topic is blockchain and to avoid you to have to support my terrible french accent the talk is in French.
This is a try, so please comment the video to see if it make sense for me to continue that way on this support with such topics.
I make a post on measuring temperature with different sensors and an objective : watch the impact of designing a correct box for you IoT you want to put in a Car.
When sun is lighting your windshield it is not a surprise to get high temperature, but did you expect to get up to 90°C when the outside temperature is about 35°C ?
The packaging have a big impact on temperature as this post will detail it.
After making LoRaWan test in a city environment, I make some test in a rural environment with the objective of evaluating the capability for being used in connected farming environment.
The result is really like what we have got in a city, eventually better in a way as the antenna position was on altitude. The following map makes with 6kbps communication shows the coverage. You can see that the coverage is really limited on the Eastern direction. This is due to higher mountains this way. Mountain are the main limiting elements and as you can see, even on short distance communication they are blocking any signal.
Read more to access the map.
For a certain IoT design I had to understand how my box design impacts the temperature of the circuit and of my battery. To understand how it works in the real environment, I made a small circuit based on an Arduino Nano to get temperature with 6 different sensors and store it in a flash memory for later use.
This post describes the way to do this multi-temperature sensor platform. Code is under GPL.
NiMh batteries
After writing a post about my experience with LiPo Batteries I’m now proposing a post about NiMh. LiPos are good batteries : not expensive with a good energy density, really easy to manage for charging. For these reason they are used in many electronic designs.
But in some applications they are not enough stable, this is as an example the case for an automotive use where the internal temperature of a car can reach higher temperature than 65°C. This is the limit for LiPos. In my experiences I had some having been destroyed due to warm temperature.
NiMh is not an optimal solution but you can find some batteries capable to support 85°C and resist to +130°C before being destroyed and have a fire risk. Varta V500HT is a good example of battery for a such use.
NiMh is less easy to use than LiPos, this post is detailing my experience.
Last week, Objenious (a bouygues Telecom company) has announced the availability of its LoRaWAN network in France. With already 32 cities covered, about 50% of people can access to the low power network. More over they have announced the deployment of 4000 antennas by end of the year to cover the whole country.
I had the opportunity to test the network and as far as now, I can say it works well, the backend is nice even if it sounds a bit not intuitive yet but for sure they will fix it soon. The good news was a communication about price, with a range of 12€ to 1€ depending on volume, the pricing is really near Sigfox one in a first look. The volume scale will be really important to see the difference as the technical offer (message limit, bandwidth, downlink limit if we have some or not).
In my point of view, Orange is the one loosing most with this announce as they are supposed to start soon with 11 cities in France and they did not yet communicate on the scaling. So now, we are waiting for Orange response and offer in this competition.
The surprising thing in the Objenious announced was the roaming capability with USA as the LoRa frequencies are not compatible between Europe and USA. As most of the device are not yet dual band and the question of detecting the location before emitting still an issue for such use-case, I do not really see how it can have a short term positive impact on project. By-the-way, I was also not aware the LoRaWAN specification for roaming was published. Is it ?
So welcome to Objenious in LPWAN french market, competition is always a good think, and what you announced sounds good and useful for object maker like me.