Category Archives: Non classé

The Sigfox Network Emulator Kit

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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.

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Let’s graph the Internet of Things

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plot-IoTIoT is generating data and to quicky look at it during the prototype phase is sounds good to plot these data in a dashboard. There are many solution you can install on your server and configure to get pretty nice dashboard. But if you want to go faster it would be really nice to have a SaaS solution for doing this. I have tested some of the solution I have found and friends helped me to found (not easy to search on google …). This post details these experiments

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Holapex – getting your first hologram at home

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holapex hologram solution

holapex hologram solution

Did you dream about getting an hologram going out from your cell-phone, this is not sci-fi but a reality for less than 15$. Holapex has raised 3500$ on kickstarter to provide a kit for doing this and it has been delivered during the last days all over the world.

 

 

 

 

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Get start with the SigRPI Shield

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Raspberry PI Shiel Hat standard

Raspberry PI Shiel Hat standard

The SigRPI shield is a HAT standard board providing SigFox connectivity to your Raspberry PI. As it is not certified for this network it can’t be used in production for this usage, but you can use it as a long range RF that does not need certification. I will later details this with a project related to this function.

By-the-way, the purpose of this board is to let you play easily with sigfox. The raspberry-pi offering a really efficient way to code and to make prototypes.

The shield comes with TD1204 (including accelerometer & GPS) of TD1208 (sigfox modem). You can use it with the standard firmware or upload your own one.

The shield can be ordered in the shop section : here

This posts details how to setup it and use it.

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Allow nginx to access a remote DB on a Centos

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If you try to access a remote database with nginx or httpd server, you will have a connection problem with error code (13) even if mysql/mariadb client works well in command line. The reason for that is a security limitation set by default not allowing httpd servers sur connect a remote DB.

To disable this limitation and make all work, just type in the command line :

# setsebool -P httpd_can_network_connect 1

You can list all the existing flags for httpd by using getsebool

# getsebool -a | grep httpd

In case you expect SELinux to be the cause of your problem, you can enable / disable it with the following functions

# setenforce 1
# setenforce 0

If you need to check what is the permission missing for SELinux you can run the audit

# tail -100 /var/log/audit/audit.log | audit2allow

 

Configure internal Lan & OpenVPN on Azure

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If you want to create a company like infrastruture on Azure you could expect to create a VPN to have a secured access to it and have an internal lan to protect you servers against external access. Basically the system provides all that you need but, as usual in the closed world of MicroSoft. The VPN server based on SSTP protocol sound hard and not documented to be used with MacOsX or Linux.

I’ll describe in this post how I fixed this issue par using an OpenVpn gateway server.

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Restoring a grub2 bootloader broken

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After I had to change a hard drive for another my linux Opensuse 12.2 grub bootloader was broken, here are some of the learning of this debugging phase :

– Restore grub to the new disk

– Start kernel manually

– Fix hard drive references

At the end, the process to recreate the bootloader and particularly to recreate the initrd file was broken, and I assume bugged. To really make it works, I had to update the whole Linux and again at the end of the process the booloader based on grub2 was impossible to execute. The solution was to select Grub (version 1) and it worked. I assume it was possible before update the whole distribution to use yast2 booloader and choose grub instead of grub2.

When you get a message like waiting for device … to apear at boot, it may be because of the initrd does not contain the right modules to access the hard drive. It appears when the motherboard has been changed.

This article is mostly notes taken during this debugging phase … so do not consider it as an howto but as a list of command and possible way to debug this kind of issues…

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TP-Link MR3040, autonomy test

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As promise, I’m looking for MR-3040 information about autonomy. This device is really interesting as it provides an internal battery to power the device on. The question was, how many time can we use it, is the autonomy good enough to have a real mobile device you don’t have to care about autonomy when bring out to public !

The first thing is to reload the battery, from 0 to 100% it takes 3:10 using the given equipment.  The next thing is to empty the battery by just doing nothing else than switch it on, as a result, the MR-3040 ran during 7hours. This is a really good result as it means that we can bring it out most of one day (or night).

The last step is to empty the battery transferring file from & to to mr3040, in this scenario, the battery autonomy should be smaller but the result is an autonomy of 5 full hours with a transfer rate about 1.5MB/s. I was expecting a shorter time so it is a good news.

The main issue I can raised after this test is the coverage area of these kind of devices (MR3040 or MR3020) really limited to a some meters and really blocked by rock walls. This is limiting the share with the neighborhood capability. It makes it more recommended to have a share into a room.