SpringBoot is a really efficient framework for creating webservices and much more. For this reason I’m using it to design my backend applications.
This framework is also well referenced on Internet and many people are downloading it and using it. All of this sounds really good and you will see you can make a webservice in less than 5 minutes following the many examples existing on Internet. As usually in this kind of technology once you have made the classical HelloWorld and university classical practices you have a lot of difficulties to make your first real program coupling different simple use-cases. So As I spent a couple of hours searching solution on Internet, this post will give you a full example of a project getting data from a MongoDB instance to provide a simple webservice.
Sigfox is a LPWA network using the free radio frequency to communicate. There radio frequencies are changing in the different zone (Europe, America, Asia…) When you are developing a device you need to test it but you are not authorized to use all these frequency from the country you are.
The Sigfox emulator is a solution for this : it allows to directly connect your device and analyze the transmission whatever the frequency you are using is. The Sigfox emulator kit is an SDR dongle with a Sigfox software for understanding, decoding the sigfox signals.
You can wire your transmitter to this receiver to not emit the signal over-the-air and legally use a non authorized frequency in your country. When you are using an authorized frequency you can simply communicate over the air.
Here is the situation : you have a function in an archive but you do not have the source code. And you would like to change the behavior of this function or intercept the call to this function.
This is possible with gcc and the -Wl,-wrap linker options. Thanks to this option you can create a new function starting by __wrap_ followed by the function name. This function will be called instead of the original one. In the function you can decide to call the original function by using its name starting by __real_
LPWA networks needs antennas and gateway to receive the device communication and transfer them to a network kernel. You can take a look to my post on the LPWA network architecture for more details.
In the LoRaWan ecosystem we call the first part of this network architecture a gateway. There are different kind of gateway : The network operator gateway with a big and efficient antenna, capable to support external weather like the Kerlink IoT Station and some low costs solution you can deploy at home or within a building (indoor) to cover a local device fleet.
The Kerlink Wirenet iFemtoCell device is a such type of gateway. this post will review how to get start with it and what we can expect in term of coverage.
IoT design a usually a matter of antenna as already seen in different previous blog post. Antenna performance is the assurance of your capacity to deploy your object in larger zone and a way to save energy by reducing transmission power.
As we will see, if you get a hardware component and simply put it in a box its radio behavior will be totally different as the box is impacting the transmission.
This post will practically show you the impact of a box on a device radio quality.
I’ve got my miniVNA Tiny+ this summer and start making test with it. A VNA is a Vector Network Analyzer. Behind this dark name, this is a tool able to analyze the radio response of your circuit and ensure your circuit is tuned to the right frequency. From the data measured by this tool you can find the right adaptation circuit to match your central frequency.
For more information about RF circuit matching, you can read this other post.
The miniVNA Tiny+ is a low cost VNA solution less than 300€ covering frequencies from 1MHz to 3Ghz. These frequencies are good for most of IoT need : LPWAN around 868MHz and Bluetooth at 2,4GHz. The steps are 10Hz for a large precision. With two ports you can measure S11 – power transmitted and received over the same port – and S21 – power transmitted from port 1 and received over port 2.
The miniVNA Tiny+ is an usb solution working with a computer connected to and a software running on the computer. The software is based on Java and may support different Operating Systems.
Posted in Hardware
Tagged RF, rf868, tools
Ordered from Kickstarter and received quickly, this solder paste dispenser really changed my life !! Now since about 3-4 month I’m using it regularly and it still mking me really happy.
It has start from a Kickstarter project I back on but failed the first time. This was disappointing as the classical tool I’m using for dispensing solder paste are really noisy. So when they did a second KS and make it I was really happy. More over they are neighbor of me (about 200km on the Est) and seeing a such good idea made from France is as a good news as a surprise.
Posted in Hardware
Tagged SMD, tools
Sometime when you want to place a SMD component on a PCB you can use a handy vacuum pump. I’ve tried different low cost model from AliExpress this summer and this post will tell you what is looking best to me for my use.
First of all, I’m not using this tool for components like small resistor, I prefer tweezers for such components. I’m using a handy vacuum pump for larger components like QPF, TSSOP, SOP, QFN…
I’ve tried 3 different tools from AliExpress from 1$ to 9$
Posted in Hardware
Tagged SMD, tools