Power constraints are becoming a critical design issue in the field of port
able microprocessor systems. The impact of software on overall system power
is becoming increasingly important as more and more digital applications a
re implemented as embedded systems, part of which are hardware (ASICs) and
part software in which a specific application is executed on a processor. I
n this paper, a data-dependent instruction-level power analysis model is pr
esented. It is compared with the average cost model proposed by Tiwari et a
l. [1] in both estimation accuracy and characterisation time, The data-depe
ndent model can be generalised to be applied to generic RISC processor. App
lication of the data-dependent model we propose sensibly reduces errors in
estimating software power consumption per clock cycle which is lower than 1
0%, in the case of the ST20-C2P core.