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--- proiecte:coap-sparrow [2017/01/23 22:48]
dan.dragan [Implementation and setup configuration]
+++ proiecte:coap-sparrow [2017/01/26 23:33] (current)
iulia.manda [Porting CoAP on Sparrow v4]
@@ Line 26: / Line 26: @@
 ===== Implementation and setup configuration =====
-The new approach required using Sparrow v4 for all three types of nodes
+The new approach required using Sparrow v4 for all three types of nodes. Porting the Device and Router applications was not very difficult because the previous model used the same microcontroller, so the only changes were for pin enablement (sensors and LEDs) and build configuration files.
+On the Coordinator side the effort was more consistent. The figure below shows the new model with a redesigned network. First of all, the build configuration files needed to be rewritten, because of the switch from ARM to AVR, not only for the CoAP application, but also for other dependencies, like ROM, 6LoWPAN subroutines and CoAP subsystem. Since the flash size was now, reduced to half, the Real Time OS required to be removed. The execution pattern was predictible, so the RTOS scheduler was easily replaced with bare metal support for the initialization tasks and callbacks.
 {{ :proiecte: coapbaremetal.png?600 | 6LoWPAN mesh network without RTOS support}}
-= 6LoWPAN mesh network on Sparrow =
+LoWPAN defines two categories of routing: mesh-under and route-over. Our project is based on the mesh-under routing method, which uses the layer-two data link layer addresses (IEEE 802.15.4 MAC and short address) to forward data packets. In a mesh-under system, routing of data happens transparently, hence mesh-under networks are considered to be one IP subnet. The only IP router in such a system is the edge router. A broadcast domain is established to ensure compatibility with higher layer IPv6 protocols such as duplicate address detection. These messages have to be sent to all devices in the network, resulting in high network load.
 In order to set up a new Sparrow wireless sensor network using COAP the following instructions should be used:
@@ Line 77: / Line 81: @@
 sudo ~/arduino-1.6.12/hardware/tools/avr/bin/avrdude -C~/arduino-1.6.12/hardware/tools/avr/etc/avrdude.conf -v -patmega128rfa1 -carduino -P/dev/ttyUSB2 -b57600 -D -Uflash:w:COAPEcho-Device.hex:i
 </file>
+The image below represents the output of a serial monitoring of the Coordinator when three other Sparrow nodes joined the network. The Coordinator assigns MAC addresses and short addresses to the routers and devices and registers them in a children table.
 {{ :proiecte: serialmonitor.png | Serial monitor for Coordinator}}
-= Serial monitor output for a Sparrow Coordinator =
+The below topology presents a coordinator, a router in the middle and two devices. The router may be used to route messages from one node destined to another. The hosts can also be sleepy devices, waking up periodically to check its parent for data, enabling very low power consumption.
 {{ :proiecte: topology.jpg?600 | Sparrow CoAP topology}}
-= Sparrow CoAP topology with a Coordinator, a Router and two Devices =
 ===== Resources =====
 * [1] https://gitlab.cs.pub.ro/dan.dragomir/dde-stack
+* [2] Jonas Olsson, 6LoWPAN demystified, Texas Instruments Incorporated
+* [3] https://tools.ietf.org/html/rfc7252

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