Week 10 – Output Devices

Week 10 assignment is to measure the power consumption of an output device.

We calculated power consumption of 3 Neopixels which were connected on a development board that we designed in Electronic production week.

We chose white light and 50/255 (20%) brightness level and measured the consumption using digital multimeter. We set the multimeter in current measurement mode, changed the prob position from voltage to current and then connected the meter in series to the power supply to measure the consumption current.

Arduino Code:

Click for Arduino Code

#include <Adafruit_NeoPixel.h>

#define PIN        D9
#define NUMPIXELS  1

Adafruit_NeoPixel pixels(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  pixels.begin();
  pixels.setBrightness(50); // 0-255, keeping it moderate
}

void loop() {
  // Turn on all 3 NeoPixels in white
  for (int i = 0; i < NUMPIXELS; i++) {
    pixels.setPixelColor(i, pixels.Color(255, 255, 255));
  }
  pixels.show();
}

Setup and Equipment Used¶

• Three Neopixels WS2818B
• Power Supply
• Digital Multimeter

Checking the power consumption

Test Setup¶

1. The PCB was connected to the Bench Power supply after uploading the program.
2. We set the voltage at 5V, max current is set at 0.5A
3. We press On/Off to power the PCB and observe the readings.

We connected power supply output to microcontroller board 5V input pin and ground.

The Microcontroller board with 3 Neopixels was consuming 0.0337 A at 5 V input supply.

Then we tried stepper motor we connected it to power supply through motor controller board.

The motor was consuming 0.011A current when supplied through 5V input.

Neopixel Power Consumption = Current x Voltage = 0.0337A x 5.0V = 0.16W

Motor Power Consumption = Current x Voltage = 0.011A x 5.0V = 0.05W

This means that if we want to run 20 Neopixels for 3 hours then we will need 3.2Whr or about 640 mAh 5V battery.

Conclusion¶

This week we learnt to calculate power consumption of electronic devices using a bench power supply.