Week #6

Microcontroller power usage

The assignment for this week was to measure the power required to run a microcontroller as a first step towards the solar project. I got this neat usb stick that connects in between your computer and the Arduino and tells you how much power it draws. I started with measuring the Arduino while its idle and not doing or connected to anything (literally uploaded an empty code file to it).

The voltage is always going to be 5 volts because this is what we get from the usb outlet of the laptop. In this case the current is 0.021 amps, and the total amounts to 0.105 watts.

I moved on to measuring other things — one of them is just a simple time-of-flight distance sensor:

And then I set out to try measuring the current of something that has different modes. I opted for using a Neopixel ring because I know the brightness and the colors, as well as the amount of lit pixels could be interesting to inspect.

This is with brightness set to 50 (out of a 0 – 255 range)

Brightness set to 100

Brightness set to 150

Brightness set to 200

Brightness set to 255

Some more tests, like measuring how the current changes with the lights' animation cycle.

This is with just one light, brightness set to 50, and the color set to fully red. On and off makes a difference of just 0.01 amps.

This is the same, but with the color set to full blue. There's a difference of 0.05 amps between on and off.

A fully white light with the brightness set to 255 has a difference of 0.16 amps between on and off states.

And a fully lit, fully white, with full brightness gets us to a whopping 0.174 amps!

I think it's interesting to note that — obviously there is a correlation between brightness and the power needed to supply it — but while the brightness could be 5 times higher between different settings, the current it draws is only about double...

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Jasmine Nackash is a multidisciplinary designer and developer intereseted in creating unique and innovative experiences.