[Tinyos-help] Crossbow PowerManagement and Energy Consumption Approximation

[scem geyik]

Hi everyone,

I wanted to model the energy consumption of a mote (micaz or mica2) in the 
code (by having an initial value and decreasing it for any action) rather 
than on hardware side (looking at the values like voltage etc. whatever) as 
I thought it would be simpler. I saw this document PowerManagement.xls on 
Crossbow's page and I have been examining it. I have questions in my mind :

1- For radio communications ,  a value is given for transmit as 12 ma and 
then according to the duty cycle a value is computed but I did not 
understand this duty cycle for transmitting a packet. I have always thought 
that duty cycle of radio was for listening for incoming data. When we put a 
duty cycle on radio, is transmission also affected by that? Even so, what if 
I never send any packets or send lots of packets. In this document energy 
consumption does not seem to change. I would really appreciate if somebody 
could explain what the document wants to tell when it gives a value for the 
xmit energy consumption. It currently does not make any sense to me. I would 
really like to have some value that I can remove from my initial energy 
value for each transmission of a packet.

2- By default, what is the duty cycle of radio and cpu? Is it %100 or some 
other value?

3- Is it healthy (not very into electrics as you can see :-) ) to give the 
energy consumption of a mote by time_in_hours * (energyconsumption rate in 
ma-hr). Therefore the energy left in a 2250 ma-hr battery is  " 2250 - 
time*energyconsumption rate" . Please keep in mind that I just want an 
approximate value if these numbers look too simple for you. I also assume 
that at the beginning , all batteries are full and in the same condition.

These are my questions for now , thanks in advance

Sahin Cem Geyik
Bogazici University - Istanbul
Computer Engineering

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