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1  Using Arduino / Networking, Protocols, and Devices / Xbee sequential sensor network: finding nearest neighbor on: December 21, 2013, 11:41:15 am
Hi all

For a project I need to build a sequential wireless sensor network. With sequential I mean that all sensor nodes are placed one after another on a straight line, with around 50m (164ft) of clear LOS between nodes. Each node will contain a PIR sensor. When it detects something, it has to send a signal to its two nearest neighbors (the one on the left and the one on the right).

Each node will have an Arduino for sensor interfacing and logging the amount and time of sensor trips. Every few hours a central node will poll all nodes for the number of sensor trips.

The sensor network also needs to be expandable quite flexible: new sensor nodes must be able to be added at the end of the existing sequential network without having to reconfigure the existing network or the Arduino in each node.

I would appreciate any tips or suggestions on how to implement this. Right now, I'm looking into the Xbee Series 2 modules. In mesh networking mode, they should be able to build and maintain the wireless network and support addition of new nodes with zero configuration (granted the Xbee radio is properly configurated). It should also allow easy polling of each node: when every Xbee module is configured as router they can relay the polling messages from the coordinator through the network.

To find the nearest neighbors, I would make Arduino keep a log of each radio address that sends packets to the node and the RSSI of each of these radios. The two radios with the strongest RSSI should be the two nearest nodes.

Of course this is theoretical speculation because I have yet to implement it. Would the above be possible and/or practical? Or are there better ways of implementing this project?

I also read that Xbee series 2 don't have the possibility of communicating the RSSI of each packet when in API mode. Is this correct?
2  Products / Arduino Due / Re: Arduino Due Mini/Nano on: October 30, 2012, 09:12:20 am
I've looked at other memebers of the same family with a smaller package that wouldn't require a huge amount of porting.
it would be possible to make a Uno sized board with one of those.
Hello Massimo

A question: why did you choose the SAM3X8E and not the lower pin count 3X8C? Wouldn't the latter be easier for smaller boards since it has 44 pins less while still retaining most of its features?

3  Products / Arduino Due / Re: Arduino Due Mini/Nano on: October 29, 2012, 03:59:24 pm
I for one would like to see a Due the size of a Uno. I don't really care that I won't be able to use all the pins. Heck, most of my advanced projects don't even use all the pins of a standard Arduino. I however do need the extra processing power, speed and memory of the SAM3x chip.

If more IO is needed, I can always buy or build expander shields based on SPI, I²C or plain old shift registers. smiley
4  Products / Arduino Due / Re: Missing RAM Pins on: October 28, 2012, 06:38:19 am
Use SMD pin headers on the side of the shield facing the Arduino board and use SMD DB9 sockets on the other side. E.g. Harting makes SMD DB9 headers.
5  Products / Arduino Due / Re: Arduino Due Mini/Nano on: October 24, 2012, 06:24:24 am
If the vanilla SAM3XE chip like you can order it from Farnell works with own-built boards, I might develop a smaller version of the Due. I developed a variant (actually: a shield) for the 8bit Arduino for use in industrial environments (think ruggedcircuits but better :p ), but boards with the dimensions of the Due or the Mega don't fit in our DIN-rail enclosures.

Perhaps it is possible to minimize the dimensions to something in the range of a Uno by omitting some pinheaders. Then you would have the same number of input/outputs of a regular Arduino, but with the processing power of the Due.
6  Products / Arduino Due / Re: Arduino Due Mini/Nano on: October 23, 2012, 04:12:26 pm
I wonder if the 'vanilla version' of the SAM3X8E can be used to make own Arduino-compatible boards, since the Due page says:
The bootloader is preburned in factory from Atmel and is stored in a dedicated ROM memory.

Would this mean Atmel ships a custom Arduino bootloader with these chips, or does the Due use a standard Atmel bootloader? If the former, will be able to burn a bootloader ourselves?  smiley-confuse
7  Products / Arduino Due / Re: No ethernet wiring on: October 23, 2012, 04:24:16 am
I could perhaps make a variant of this board with the EMAC pins wired to a PHY and a Magjack (or to a header, with the networking components on another shield), but then someone would have to port the 32bit ethernet library to Arduino smiley-sweat .
8  Products / Arduino Due / No ethernet wiring on: October 22, 2012, 02:28:39 pm
One of the reasons i was looking forward to the Due with its SAM3X8E mcu was the integrated Ethernet MAC. Because of this EMAC the only component an ethernet shield would need to have was a simple PHY and a RJ45 jack with magnetics, alleviating the need for the relatively expensive and power hungry Wiznet chip on which the current ethernet shields are based.

Unfortunately it seems the Due designers didn't bother wiring the EMAC pins of the SAM3X8E to a pin header. In the schematic there is an ETH header that serves as a breakout for the EMAC pins, but in the board file this header is left out and the EMAC pins are terminated.

Quite a missed opportunity imo, or are the designers planning on releasing another board with this ETH header populated sometime in the future?
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