Do you know sigfox ?

SigFox is a French radio frequency technology allowing a really low cost data transfer from Machine to Machine. Compared to GSM, this solution have some great advantages : it costs only 10-16€ per year and the energy consumption is about 1000 time less. For sure there is some constraint and the main one is the quantity of information you can transmit. In fact you have a limit of 150 sent messages / days with a length of 12Bytes. It’s not big but is it enough for a lot of IoT and M2M applications.

This technology works as a modem you can connect to any platform like Arduino, RaspberryPi. The chips are provided by TelecomDesign from a cost about 15€. The starter kit is about 150€ here.

The great advantage of this technology, in a operator point of view is the low density of the architecture where you need only 1000 antennas to cover a territory like France. As a consequence, at this time, already 90% of the country is covered by this technology.

Create a controlled 12V output for Raspberry Pi

I had to add a 12V controlled output for my raspberry Pi to connect a radio frequency system to my Pi. This system just need 12V to start transmitting but it needs 12V ! The raspberry can offer 5V or 3.3V. The solution is to use a currant elevator system. The one I built is based on a Texas Instrument component TPS6734, able to deliver 120mA / 12V with a 3.3V input.

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Getting start with rfrpi card v1.0 – rf433 for raspberry pi

rfrpi_2RfRpi card is a RF433 emitter and receiver add-on of Raspberry Pi. This card is based on high quality receiver and transmitter I have selected after tests you can find here and here. This article describes how to get start with this shield.

To buy this shield the best way is to sent me a comment on this post, the price is 60€

The Shield is now working with Raspberry PI B+ and previous versions. The Shield is also working with Raspberry PI 2+. For these two last version you need to compile a kernel driver.

 

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Control a high power circuit with arduino

irf9540I had to control power on an external circuit using an Arduino. the objective was to delay the power-on of a device consuming about 3A. One of the solution is to use a relay but it is a quite expensive solution another one is to use a Mosfet. This is the solution I’ll describe here.

 

 

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making a 5V – 3/4 A power supply for car

car_alimFor one of my project, I needed to have a >3A power supply to put in my car, delivering stable 5V. For this I tried different power supply from ebay used for phone & tablets. One of them was not so bad if you connect it after engine start. The main issue with these power supply is the poor quality of the filtering and engine start spike cancellation. As my circuit is sensitive to this spike, I decided to build my own power supply.

Here is the summary of this experience … click next !

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AIX network debugging

Since a couple of day at work I had to investigate on some network issues for an application, it seems that we have a strange ARP configuration that may be the main issue… by the way, I discovered another strange thing where icmp packets sent in burst mode (like a flood) are lost at variable rates. Here is the note on my investigations

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Arduino AtMega328p low power consumption

For one of my projects, I want to have a really low power consumption device to be able to use a battery for many month. For this I implemented a low power solution as described here. I’ll try to simplify it a little bit and document it a little more …

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