Interactive web site of Télécom ParisTech's ELECINF344/ELECINF381 Robotics and Embedded Systems classes (a.k.a. ROSE, 2012 session).


[MAESTROSE] Codec, RSSI and first tests on the board

Friday Alexis soldered our first PCB, that you can admire below :

She is now waiting for her 12 little sisters :)

Thanks to that, Guillaume was able to port our existing code on the module, after the traditional blinking LED he was able to communicate in ZigBee with the module. Unfortunately all of a sudden openocd has been reporting some JTAG-DP STICKY errors and assumes that the flash memory is in protected mode. All our attempts to flash some new code with JTAG or to use the integrated bootloader have been unsucceful and Guillaume has spent the day working on it.

In the mean time Aurélien has been writting code to use the codec. It is now ready to be tested on the board but we have to fix the upper mentionned problem first.

For my part I was in charge of the evaluation of the use of RSSI based location that we will be able to do on the project. Unfortunately no big surprise we still encountered the same problems than before. Unlike what physics could let us expect, the RSSI in not always decreasing with the distance, it goes up and down with the distance and the value is almost the same at 12 and 7 meters for example while it is much higher for 10 meters. The following histogram show these disapointing results.

Nevertheless we have been able to make use of the RSSI on very short and fixed distances. We placed 5 F103 boards 30 centimeters apart in line. Each card used RSSI to locate its closest neighboor, and we were able to make them number themselves from one extremity to the other from 0 to 4.

At the moment we plane on using RSSI in this way only, it’s quite restrictive, but we have an idea of a nice use that we can make of it :)

Bertrand Mermet

Possibly related posts:

  1. MAESTROSE – Distance evaluation
  2. First life signs of our board
  3. SaMoRA : chips and first tests
  4. MAESTROSE – No more nRF24L01P
  5. Some tests on Zigbee

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