Take a look at SigFox radio signals with airspy usb software defined radio

I recently bought an AirSpy mini SDR (Software defined radio) dongle. Understand, it is a radio scanner you connect on your computer able to analyze radio communications on a large frequency range from 24MHz to 1,7HGz. The main difference between this SDR and the low cost one based on RTL 2832 + R820T is the spectrum view up to 6Mhz, the TCXO working with 0,5ppm and globally the quality of the solution and the availability of libraries. What is presented here is also valid for RTL based dongle.

With this tool you can see what is happening on the radio frequencies in real time, compare power, listen radio … This post is presenting how to install it and use it on windows & Mac Os X.

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GPS antenna comparison

antennaI’m using different GPS antennas with different price, size and gain and I had never compared the result in a real live test. So now it is done and the result are good to share.

My test condition are quite bad and we can’t really consider this as a scientific bench but, experimentally it sounds like a real life test.

So the test is to connect an antenna to a TD1204 with a GPS code on it and test the time it makes to fix the position and get some note about signal level, satellites in view… I used in fact 2 TD1204 : one with a reference antenna to ensure we have equivalent condition from one test to the others. The tests are made indoor where the sensitivity is an important factor. This post detail the results.

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Have a good start with Telecom Design EFM32 starter kit

Telecom Design kitAfter making my kit on my own, I finally got the official Telecom Design TD1204 kit (thank you TD) There is no big issues to use it once you have the right entry point, but as I had some email exchange with support to be fully ready for using it, I’m prefer to share some words with you on what to do and how it works.

Basically, the TD kit is an EFM32 Tiny Gecko Starter kit (STK3300) with some little modifications.  The EFM kit have two interesting functions : in own a Jlink JTAG/SWD programming and debugging interface and its EFM32 MCU can be use to monitor power consumption with precision.

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Measure and store multiple temperature with Arduino

Arduino Temperature SensorFor 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.

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Let’s play with NiMh battery

NiMh batteries

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.

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Cheap TFT / LCD touch screen for RaspberryPi with Jessy

TFT screen on a raspberryPi

TFT screen on a raspberryPi

This week I had to play with some TFT screen for RapberryPi for making a prototype for a local company. You can find many TFT screen on Internet but most of them are not coming with a nice fresh documentation for being use and it is kickly a mess to get it start with them. I ordered different one having the same 3.2” size matching my need and got 2 of them for starting tests.

This post details how to use a such screen for displaying a picture on it from a console line.

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Measure waveform duration with EFM32 / TD1208

tim10Measuring a pulse duration in a pulse train was my last week headache with the TD1208 and the not so well documented EFM32. Basically, my objective was to activate a timer on a pulse train to measure the duration of the pulse. This duration was measured about 100uS and occurred at 1 Hz.

My choice was to rise an interrupt on each signal front (raising and falling) and measure the duration between the two first interrupt call. Some reset function ensure we are measuring the low state duration (100uS) not the high state duration (1s). This part will not be described here.  The purpose of this post is to describe the main hole I fallen in.

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RN2483 – LoRa – upgrade firmware

Microchip RN2483 Lora

Microchip RN2483 Lora

The microchip device is in most of the case delivered with a 0.9.5 a version 1 seems to be available even if not downloadable from microchip product webpage.

This link contains a version 1.0 and a java tool that helps to configure the chip with a graphical interface. It is really usefull.

Main problem I found with the tool: it is not possible on a MAC to open the firmware file to load. Other functions are accessible. On W7 it is possible to flash the device :

 

  • Connect the device with bootloader mode check activated
  • Select the firmware hex file
  • Select 19200 bps as for speed
  • Clic … sometime it is short (and not working) sometime it is longer and working
  • At end, execute a hard reset and search for the module it should appear.

Actually on May 1st 2016 the current firmware version is 1.0.1 you can get it following this link. This version is the one validated for network operators like Objenious.

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