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See the Power Consumption of your Tmote Sky in Real Time (Updated 13 Nov 2007)
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Written by Adam Dunkels,
Tuesday, 06 November 2007 |
A pioneering recent addition to Contiki is its ability to estimate the total energy consumption of the system on which Contiki is running. Knowing the current power consumption is very important in wireless battery-powered systems.
We will demonstrate this mechanism at the SenSys 2007 conference in Sydney, Australia on the 7th of November, but you can now try it out yourselves. All you need is a few Tmote Sky boards, Java, and Cygwin! Read on for download and installation instructions.
Download (Updated 13 Nov 2007)
Download the binary here: contiki-energest-demo.zip
Updated on 13 Nov 2007: now includes the missing Python serial library,
(Source code: contiki-2.x-energest-demo.tar.gz - the code is in examples/energest-demo)
Installation Instructions for the binary
Cygwin and Java (JRE) needs to be installed. The demo has been tested on Microsoft Windows, but probably works under Linux too.
You need between two and eight Tmote Sky boards to run the demo: one sink and between one and seven nodes. The nodes are numbered from 42 to 48, and 41 is the sink node.
Step 1: Unpack the zip file
unzip contiki-energest-demo.zip
Step 2: Change directory to the demo directory
cd contiki-energest-demo
Step 3: Connect the sink node to the PC. Remove all other Tmote Sky nodes from the PC.
Step 4: Upload Contiki to the sink:
make upload-sink
Step 5: Remove the sink node from the PC.
Step 6: Connect one of the non-sink nodes to the PC
Step 7: Upload Contiki to the node:
make upload-node-42
This takes some time. The red LED should be lit when the uploading is finished. We have found that in some cases brand new Tmote Sky boards seem to cause a problem with Contiki and the red LED does not light up. If so, try to wait a few minutes (~10 minutes) with the Tmote Sky either inserted in the PC, or powered with batteries. If the red LED goes on after these minutes, repeat the "make upload-node-XX" to upload Contiki again.
Step 8: Remove the Tmote Sky from the PC.
Step 9: Insert batteries into the Tmote Sky. The red LED should light up.
Step 10: Repeat step 6 to step 9 for all non-sink nodes. Replace "make upload-node-42" with "make upload-node-43", "make upload-node-44", and so on.
Step 11: Insert the sink node to the PC again.
Step 12: Run the Java program:
make rundemo
NOTE: this uses the first Tmote Sky it finds as a sink. Therefore, make sure that only one Tmote Sky (the sink) is inserted.
Step 13: Push the "user" button on the Tmote Skys and watch their power consumption go up and down.
Demonstration Description
Contiki continuously estimates the energy consumption of the system. In this demonstration, seven Tmote Sky nodes, running Contiki, estimates their energy consumption and send their power to a sink node. The sink node is connected to the PC, and reports the nodes' power to a Java program. The Java program shows the nodes' power consumption for the last second.
When pushing the button on the nodes, they cycle through seven states as below. This is reflected by their power consumption, as shown in the Java program. The different states are:
* Red LED: sending one packet per second
* Green LED: radio listen 1% duty cycle
* Green, red LEDs: radio listen 10% duty cycle
* Blue LED: radio listen 100%
* Blue, red LEDs: radio listen 10%, CPU low-power mode disabled
* Blue, green LEDs: sending data 1.2 kilobytes/second
* Blue, green, red LEDs: sending data 12 kilobytes/second
When sending data, the radio is turned on for a while before the transmission to check if it is possible to send the packet. This is the reason why energy is spent on radio listening even when the nodes are only sending data.
Read More
Adam Dunkels, Fredrik Österlind, Nicolas Tsiftes, Zhitao He. Software-based on-line energy estimation for sensor nodes. In Proceedings of the Fourth Workshop on Embedded Networked Sensors (Emnets IV), Cork, Ireland, June 2007.
[ bib | .pdf ]
Adam Dunkels, Fredrik Österlind, Nicolas Tsiftes, and Zhitao He. Demo abstract: Software-based sensor node energy estimation. In Proceedings of the Fifth ACM Conference on Networked Embedded Sensor Systems (SenSys 2007), Sydney, Australia, November 2007.
[ bib | .pdf | Abstract ] |
