Author Archives: Paul

Make your IoT design on Sigfox or LoRa ?

LoravsSigfoxOnce you have found the great idea of the year and you want to start implementing your first prototype it is time to choose the right technology. Some would say you should not choose at this step and implement both at end but in my point of view it looks like and economical mistake to do this way. Prototype is to demonstrate and final product. It can request another technology, for sure. But in my point of view the best is to take the right one at the beginning. For most LoRa and Sigfox are both equivalent or for some others one is over the other one, best depends who you ask. In my point of view, if I consider my 2-3 years sigfox experience and my starting experience on LoRa with 1 year background research on it, there is no magic answer. Context of your idea is the keypoint then you have some technical elements to take into account to finalize your decision.

This post will try to illustrate where each of the technology is the best and give you some decision keypoints.

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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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Simple LoRa GPS tracker based on RN2483 and L80

LoRa GPS Tracker
LoRa GPS Tracker

Todays work was to make a simple GPS tracker communicating over LoRaWAN to check the coverage of my LoRaWan gateway in the city. Basically this tracker reports a position per minute to the network. If coverage is good, position will be recorded in the backend. That’s all !

This post details how to do it easily with the low cost and common components : Arduino for the master, Microchip RN2483 for LoRaWan communication and L80 for GPS positioning.

 

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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.

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Flash a TD1204 over J-Link

For flashing a TD1204 / TD1208 over J-link you need to use the following commands:

JLinkExe -device EFM32G210F128 -if swd -speed 1000
J-Link> loadbin xxxxx.bin,0
...
J-Link> r                          # reset
J-Link> g                          # go

Total programming time is about 5 seconds. The circuit between the segger connector and the TD is the following one. (do not forget to connect VDD circuit to Segger VTref.

td1204 / j-link cable
td1204 / j-link cable
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