RF433 – Raspberry PI GPIO kernel driver for interrupt management

You may have read some of my post about RF433 and Raspberry PI. Basically with RPI 1, I was using wiringPi interrupt handler to manage the RF433 decoding. The problem is that with RPI2 and RPI B+ the delay to take an interrupt that was becomes unpredictable. And the timing constraints are not respected. As a consequence part of the messages are loss because for these delay.

One of the solution (the software one) is to be more efficient to proceed the interrupts and the way to do this is to compile a kernel driver for directly handling the interrupts. This is what this post is about. This comes to complete the RFRPI code and associated hardware. A complete source code and software for using it is on the rfrpi bitbucket repository.

Challenge of the coming days : write a kernel driver to manage interruption quicker on a raspberry pi 2. I’m happy to find a lot of example on Internet and in particular this one, that is really looking like what I’m trying to do. This post is describing all the step needed to do this.

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Let’s graph the Internet of Things

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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Extend TD1204 Standard firmware to simplify GPS

TD1204 / Sigfox & GPS

TD1204 / Sigfox & GPS

The TD1204 modem firmware is a easy to use solution for sending message to Sigfox network. It starts to be complex when you want to create your own message including the GPS position. The standard firmware returns the satellite NMEA frames in text mode and you have to process it.

To make it simple I built a modification of the standard modem firmware to add an extra command to enrich a message with a GPS coordinate automatically.

 

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Holapex – getting your first hologram at home

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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First step in LoRa land – microchip RN2483 test

Microchip RN2483 Lora

Microchip RN2483 Lora

After spending some time reading and writing about LoRa it was a good time to make some real test of this technology.

As actually there is no network for LoRa, as much as I know, in my town, I expected to start a simple LoRa test (point to point and not as part of a WAN). I just bought some RN2483 LoRa module from Microchip online and also get some from Avnet (thank you Guillaume)

 

The module is easy to solder on a prototype board and get its command over a serial port. I choose to make two modules :

  • The first one is connected to a FTDI cable and will stay at home as a basestation
  • The second one is connected to an Arduino and will be a mobile device for my test

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What is LoRa ?

Lora-300x171LoRa is a dedicated network for Internet Of Things and Machine2Machine communications. It is actually the main competitor against SigFox.

As LoRa is actually rising in France with different announce from 2 of the main cellular operators deploying the network, it is a good time to have a post on what it is, how it works and what differs compared with SigFox.

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Silabs EFM8 a low cost microcontroller based on 8051 core

EFM8 chip

EFM8 chip

If you my blog and the lesson section you may notice my interest for 80×51 micro-controller family. Silicon Labs has recently launch a new 8b family based on this core.

With price less than 1 euros, they are interesting candidates for low cost hacking and hardware design. Even the programming cable is not really expensive ( $35 + port + Tax ) and the development environment is free.

EFM8 provides a 50MHz core with all the usual I/O – Serial, I2C, SPI. Plus 12 bit ADC, voltage regulator, oscillator…

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Telecom Design SDK decode GPS frame

The Telecom Design SDK contains a function to encode GPS coordinates : TD_SENSOR_EncodePositionXY this function from the SDK allow to choose the size of the GPS encoded data and to reduce it. This post explains how this function works and gives a php implementation to decode it.

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