image.png

Reference Standard:

  1. The design must not consume, transfer, discharge, or otherwise expend more than 30W of power at any point in time and within any component of the design during its operation.
Component/Group Energy Values
STM32 Wattage = 0.29 W
Microphone Omnidirectional Resistance = 1.5kΩ
AD8232 Heart Rate Monitor Resistance = 1kΩ
Output Wire for Skin Conductivity Resistance = 10Ω (shared with Input Wire)
Input Wire for Skin Conductivity Resistance = 10Ω (shared with Output Wire)
Big RGB LED Resistance = 1kΩ (shared with IR Emitting LED)
IR Emitting LED Resistance = 1kΩ (shared with Big RGB LED)
LCD Screen Resistance = 2kΩ
I2S Audio Breakout Resistance = 2kΩ
Speaker Resistance = 3Ω
HW-203 SD Card Reader Resistance = 1kΩ
IR Receiver Resistance = 1kΩ

To calculate the total resistance of the design, we will add up the various circuits connected to the STM32

Audio input = 1.5kΩ

Heart Rate Monitor = 1kΩ

Skin Conductance Test = 10Ω

LED & IR LED = 1kΩ

LCD Screen = 2kΩ

I2S Audio Output = 2kΩ + 3Ω = 2.003kΩ

SD Card Reader = 1kΩ

IR Receiver = 1kΩ

Adding up the resistance, we get a total resistance of:

(1.5 + 1 + 10 + 1 + 2 x 2 + 2.003 + 1 + 1)kΩ = 21.503kΩ

Note: the design has 2 LCD screens

Given this total resistance, we can calculate for the wattage of the system by calculating with the system voltage, 5V.

I = V / R

I = 5V / 21.503kΩ