222 lines
7.4 KiB
Markdown
222 lines
7.4 KiB
Markdown
Contiki client for sensd
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========================
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Sensd README describes the concept. sensd code is on github.
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sensd - A WSN Internet GW, hub, agent, proxy & cloud
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====================================================
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Authors
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--------
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Robert Olsson <robert@radio-sensors.com>
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Jens Laas <jens.laas@uadm.uu.se>
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Contributors
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------------
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Abstract
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--------
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We've outlined, designed and implemented and very simple concept for WSN
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data sharing, including data collection, storage and retrieval using
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standard text tools. The concept restricts Internet access to WSN
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motes and acts agent not to expose motes directly for robustness and
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security reasons. Low level, physical or link WSN protocol can be used.
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including 6lowpan, RIME etc and any type of Radio Duty Cycling (RDC).
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sensd works on the application layer. A TCP connection initiates an
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implicit "subscribe". The M2P model is currently supported.
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Key concepts
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------------
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* Agent. sensd works as an agent and does not allow direct Internet
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access to motes. Recall motes are constrained in most aspects and
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can not support many connections, has weak security etc.
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* Hub. Share the data from the root or sink node over TCP. In effect sensor
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data can be sent over Internet to be shared over among TCP active listeners.
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The TCP connection initiates an implicit "subscribe".
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* Proxy. The support proxy functions over ipv4 and well as ipv6. Sensd can
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forward to a proxy on a public IP. The typical case is when GW is behind
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a NAT.
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* WSN RP "rendez-vous point". A concepts where data from various WSN nets
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are merged. This models a "cloud service" functionality for WSN networks.
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sensd can be used both to forward data to RP. It can also work as the RP.
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RP receiving WSN data and allowing multiple TCP listeners.
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* All programs are written C, script in Java and bash. Designed for small
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footprint and with minimal dependencies. sensd runs on Raspberry Pi and
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Openwrt.
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* This work introduces a simple tag format for sensor data. The overall
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idea is that data tagging is an "agreement" between producers and consumer.
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Tags are simple are description of the data. Example T=25.2. where T=
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is the tag 25.2 the value. Most likely this a temperature. But we
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can't be sure since we don't know since this is an agreement between
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the producer and the consumer. Tags are also used for identification.
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Example tags, E64= Where globally unique ID can used. Another more
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relaxed example is TXT= a user description. See docs.
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* Geotagging and timestamping is supported via tags.
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* Ecosystem support. There are telphone apps to for data monitoring and
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and plotting. Android app can act as WSN-agent and forward to proxy/RP.
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* The concept also includes a mapping to URI (Unified Resource Identifier)
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to form a WSN caching server similar to CoAP using http-proxy.
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* Copyright. Open-Source via GPL. Projecet used github.com
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Introduction
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------------
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This is collection of software to implement data monitoring and data collection
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from WSN Wireless Sensor Networks. The goal is to have a very simple,
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straight-forward and robust framework.
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The scenario: One or several motes is connected to USB or serial port to gather
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received information from connected WSN motes. Data can be visualized in
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several ways.
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* Sensor data report can be transmitted and propagated throughout the
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Internet. sensd acts as server and sends incoming report to active
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listeners.
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* Data is kept in ASCII with tagging and ID information. Data is conveniently
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handled, copied and viewed with standard text utilities of your OS.
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* Last mote report is cached into the file system suitable for URI use. The
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Format is SID/TAG. Typical tags are EUI64 and unique serial numbers. The
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different TAGS are left for mote user to define. Although the TAGS used in
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our example setup are included in this draft for example purposes.
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Both formats can easily be stored or linked directly in web tree to form a
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URI to format WSN logging/datafile or caching service.
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A daemon that reads WSN mote reports from USB/serial and stores data in a ASCII
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data file. Default is located at _/var/log/sensors.dat_
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Addtional components
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--------------------
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* seltag [More info] (https://github.com/herjulf/sensd/blob/master/seltag/README.md)
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* js A set of Java-scripts can plot, print and visualize sensor data from
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sensd directly in your web-browser.
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* documentation and sample files. [More info] (https://github.com/herjulf/sensd/blob/master/seltag/README.md)
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* Read Sensors Android app. [Source Code] (https://github.com/herjulf/Read-Sensors)
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Datafile logging
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----------------
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Below is and example of the anatomy of a sensors.dat file we are currently using in our WSN
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data collection networks.
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2012-05-22 14:07:46 UT=1337688466 ID=283c0cdd030000d7 PS=0 T=30.56 T_MCU=34.6 V_MCU=3.08 UP=2C15C V_IN=4.66
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2012-05-22 14:11:41 UT=1337688701 ID=28a9d5dc030000af PS=0 T=36.00 V_MCU=2.92 UP=12C8A0 RH=42.0 V_IN=4.13 V_A1=3.43 [ADDR=0.175 SEQ=33 RSSI=21 LQI=255 DRP=1.00]
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Each line is a mote report. They start with date and time and are followed by a set of
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tags. The tags is different for different motes. In other words they can
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send different data. Essential is the ID which should be unique for each mote.
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The information with brackets is information generated by the receiving mote
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and is not a part the motes data. Typically RSSI (Receiver Signal Strength
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Indicator) and LQI (Link Quality Indicator)
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Internet sensor data
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--------------------
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Start sensd with the `-report` option. This enables reports to be transmitted
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over IP to remote listeners. Default TCP port 1234.
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Server side example:
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sensd -report -p 1234 -D /dev/ttyUSB0
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Client side. Example using netcat:
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nc server-ip 1234
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URI format
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----------
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URI (Unified Resource Identifier) displays the node ID and the tags in a file tree.
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It is easy to export this into a web tree to form a URI similar to a CoAP gateway.
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Example: In our case we have a unique sensor ID followed by the different data
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fields represented by "tags".
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/tmp/WSN1-GW1/281a98d20200004a:
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DRP ID LQI PS RH RSSI SEQ T V_IN V_MCU ADDR
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/tmp/WSN1-GW1/28be51ce02000031:
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DRP ID LQI PS RH RSSI SEQ T UP V_IN V_MCU ADDR
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Read Temp from a sensor:
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cat /tmp/WSN1-GW1/281a98d20200004a/T
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19.44
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And it's very easy to link this tree into a web-server.
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GPS support
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-----------
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Positioning support has been added via GPS device connected to serial
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or USB port. Tags added when enabled GWGPS_LON & GWGPS_LAT.
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GPS code from. https://github.com/herjulf/gps_simple
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Getting the source and building
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-------------------------------
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Code is stored in github. Typically procedure below is the very straight-
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forward unix way:
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git clone http://github.com/herjulf/sensd
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cd sensd
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make
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Put your binaries after your preference:
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Pre-built binary versions
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--------------------------
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For x86:
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Sensd and friends are available in Bifrost/Linux packages. Those packages are
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statically linked and can be used on most x86 Linuxes. 32-bit compiled.
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http://ftp.sunet.se/pub/Linux/distributions/bifrost/download/opt/opt-sensd-2.3-1.tar.gz
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Use
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---
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The WSN data logging and caching concept is in actual use with Contiki, RIME
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broadcast application.
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Tips
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----
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One can use netcat to listen to reports:
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Example:
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nc radio-sensors.com 1235
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To save in file use nohup:
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nohup nc radio-sensors.com 1235 > /var/log/sensors.dat
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As sensd used TCP and ASCII encoding. tetlnet and web-browsers can be used
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as well.
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