12. Output devices

Group Assignment

In Group Work, my team tested the NeoPixel Ring with different amounts of pixels and measured the power that it consumed.

Group Work Page

Individual Assignment

This week I added a 20x4 LCD to my microcontroller board and program it to print different things to test if it consumes different power.

Setup

At the beginning, I met a problem that I connected the LCD with 3V source. Thus, it didn’t get enough power to turn on. It took me a while to check that if my code was wrong and what is the problem. After I tried to look again my voltage source, I recognized that 3V is not enough power.

First, I need to connect the LCD through I2C with VCC, GND, SCL, and SDL pins. I also use a measurement USB to connect between my laptop and my microcontroller board.

Before I connect the LCD, I check how much power my board consumes. P = 5V * 0.07A = 0.35W. Around 0.35W

After that: P = 5V * 0.15A = 0.75W

Code

First code, I tried some simple print on the LCD.

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 20, 4);

void setup()
{
  lcd.init(); // initialize the lcd
  lcd.backlight();
  lcd.clear();
  lcd.setCursor(7, 0);
  lcd.print("Hello");
  lcd.setCursor(6, 1);
  lcd.print("I'm Khai");
}

void loop() {
}

The LCD still consumes the same power.

Special

Each character in the LCD is composed of 40 pixels (8 rows and 5 columns). Thus, I tried some custom characters on the LCD.

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 20, 4); 

byte customChar0[8] = {
  0b00000,
  0b01010,
  0b11111,
  0b11111,
  0b01110,
  0b00100,
  0b00000,
  0b00000
};

byte customChar1[8] = {
  0b00100,
  0b01110,
  0b11111,
  0b00100,
  0b00100,
  0b00100,
  0b00100,
  0b00100
};

byte customChar2[8] = {
  0b00100,
  0b00100,
  0b00100,
  0b00100,
  0b00100,
  0b11111,
  0b01110,
  0b00100
};

void setup()
{
  lcd.init(); 
  lcd.backlight();

  lcd.createChar(0, customChar0); 
  lcd.createChar(1, customChar1); 
  lcd.createChar(2, customChar2); 
  lcd.setCursor(2, 0);
  lcd.write((byte)0); 

  lcd.setCursor(4, 0);
  lcd.write((byte)1);

  lcd.setCursor(6, 0);
  lcd.write((byte)2);
}

void loop()
{
}

Here is the result: