Evaluations

We have created an estimate of power consumption. The following graph compares percentage duty cycle, frequency of performing a data, and battery life. It is based on a single coin cell battery as the power supply and the power ratings given in the data sheets for the processors.

The power rating for the ATSAMR21 is 3.37 mA when active and 4.06uA when in standby. An additional 11.8 mA is added to this when transmitting or receiving with the radio.

The power ratings for the STM32F4 is 1.9 mA when active and 1.8uA when in standby.

Timing for the calculation of power consumption during classification was based on the classification of a window of 32 reading from 9 axes of sensor data. Timing for the calculation of power consumption during transmission was based on the data sheet’s values for transmission speed and initialization time.

The sensors were not considered in this chart because they can be run at many different power levels. For instance when only using the accelerometer and the magnetometer, the MPU 9150 draws from 10 uA to 3.9 mA depending on the configuration, and can be turned on and off for power saving.





The next chart shows a comparison of battery life for constant transmission of sensor data during sensor data collection time. This is assuming the given duty cycle on the X axis for time spent collecting values.