11. Output devices¶

Assignment¶

Group Assignment¶

• Measure the power consumption of an output device.

Individual Assignment¶

• Add an output device to a microcontroller board you've designed.
• Program it to do something.

Motor Types¶

Servo Motor¶

Pros: - Simple to control
- Good for automated seats with slow and smooth movement

Cons: - Limited weight capacity
- May struggle with very heavy seats
- Limited range

DC Gear Motor¶

Pros: - Stronger than a servo
- Smooth motion
- Can be used with limit switches for precise stopping

Cons: - Requires a motor driver circuit
- Powered and not spinning = stalling, which will destroy the motor

Stepper Motor¶

Pros: - Precise control
- Good for slow & controlled lifting

Cons: - Needs a driver (e.g., A4988)
- More complex than DC motors

NEMA 17 Stepper Motor¶

NEMA 17 is a standard-size stepper motor commonly used in 3D printers, CNC machines, and robotics. The number "17" refers to the 1.7 x 1.7 inch (43.2 x 43.2 mm) faceplate size.

Specifications¶

Compatible Stepper Drivers¶

• A4988
• DRV8825
• TMC2208 / TMC2209

Applications¶

• 3D printers (e.g., Creality Ender 3, Prusa i3)
• CNC machines
• Robotic arms
• Automated conveyor systems

Note: Always check your stepper driver's current limit and cooling requirements to avoid overheating.

In reality, it looks like this:

Code¶

#define STEP_PIN 9
#define DIR_PIN 8

void setup() {
  pinMode(STEP_PIN, OUTPUT);
  pinMode(DIR_PIN, OUTPUT);
  digitalWrite(DIR_PIN, HIGH); 
}

void loop() {
  digitalWrite(STEP_PIN, HIGH);
  delayMicroseconds(500);
  digitalWrite(STEP_PIN, LOW);
  delayMicroseconds(500);
} 

Servo motor¶

JX Servo PDI-6225MG-300 – Specifications¶

In reality, it looks like this:

Code¶

#include <Servo.h>

Servo myServo;

void setup() {
  myServo.attach(9);
}

void loop() {
  for (int angle = 0; angle <= 180; angle++) {
    myServo.write(angle);
    delay(15);
  }

  delay(500);

  for (int angle = 180; angle >= 0; angle--) {
    myServo.write(angle);
    delay(15);
  }

  delay(500);
}

Display¶

Types of Displays¶

• LCD (Liquid Crystal Display): Basic alphanumeric screen, low power, common in Arduino projects.
• OLED (Organic LED): High contrast, thin, and energy-efficient display with bright visuals.
• TFT (Thin Film Transistor): Full-color display with high resolution, ideal for images and GUI.
• 7-Segment Display: Simple numeric display used for counters, timers, etc.
• LED Matrix: Grid of LEDs for showing text, animations, or patterns.
• E-Ink Display: Looks like paper, ideal for low-power applications like e-readers.

What is I2C?¶

I2C (Inter-Integrated Circuit) is a communication protocol used to connect low-speed devices like sensors, displays, and microcontrollers.

• It uses only two wires:
• SCL (Clock Line)

• SDA (Data Line)

• One device acts as a master (usually the microcontroller), and others are slaves.

• Each device has a unique address, so multiple devices can share the same two wires.

• I2C is commonly used in Arduino and embedded systems because it reduces wiring and supports multiple devices.

In reality, it looks like this:

Code¶

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Устанавливаем адрес LCD (обычно 0x27 или 0x3F)
LiquidCrystal_I2C lcd(0x27, 16, 2);  // 16 символов, 2 строки

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

  lcd.setCursor(0, 0);     
  lcd.print("Hello, world!");

  delay(2000);             

  lcd.clear();             
  lcd.setCursor(0, 0);     
  lcd.print("Fab Academy 2025");
}

void loop() {

}

Speaker¶

Piezo Buzzer¶

A piezo buzzer is a small speaker-like component that makes sound using piezoelectric vibration.
It is commonly used for:

• Making beeps or alarms
• Indicating button presses
• Audio feedback in embedded systems (Arduino, etc.)

There are active and passive types: - Active buzzer: makes sound when powered (just needs voltage) - Passive buzzer: needs a signal (like PWM) to make sound

• Making beeps or alarms
• Indicating button presses
• Audio feedback in embedded systems (Arduino, etc.)

There are active and passive types: - Active buzzer: makes sound when powered (just needs voltage) - Passive buzzer: needs a signal (like PWM) to make sound

In reality, it looks like this:

const int SPEAKER=9;
int notes[] = {
1318, 1318, 1318, 1046, 1318, 1568, 784,
1046, 784, 659, 880, 987, 932, 880, 784,
1318, 1568, 1750, 1396, 1568, 1318, 1046, 1174, 987,
1046, 784, 659, 880, 987, 932, 880,
784, 1318, 1568, 1750, 1396, 1568, 1318, 1046, 1174, 987,
1568, 1480, 1396, 1244, 1318, 830, 880, 1046, 880, 1046, 1174,
0, 1568, 1480, 1396, 1244, 1318, 2093, 2093, 2093,
1568, 1480, 1396, 1244, 1318, 830, 880, 1046, 880, 1046, 1174, 1244, 1174, 1046,
};
int times[] = {
150, 300, 150, 150, 300, 600, 600,
450, 150, 300, 300, 150, 150, 300, 210,
210, 150, 300, 150, 150, 300, 150, 150, 450,
450, 150, 300, 300, 150, 150, 300,
210, 210, 150, 300, 150, 150, 300, 150, 150, 450,
150, 150, 150, 300, 150, 150, 150, 150, 150, 150, 150,
0, 150, 150, 150, 300, 150, 300, 150, 600,
150, 150, 150, 300, 150, 150, 150, 150, 150, 150, 150, 300, 450, 600,
};
int delays[] = {
150, 300, 300, 150, 300, 600, 600,
450, 450, 450, 300, 300, 150, 300, 210,
210, 150, 300, 150, 300, 300, 150, 150, 450,
450, 450, 450, 300, 300, 150, 300,
210, 210, 150, 300, 150, 300, 300, 150, 150, 600,
150, 150, 150, 300, 300, 150, 150, 300, 150, 150, 150,
300, 150, 150, 150, 300, 300, 300, 150, 600,
150, 150, 150, 300, 300, 150, 150, 300, 150, 150, 450, 450, 450, 1200,
};
void setup(){
for (int i = 0; i < 75; i++){
tone(SPEAKER, notes[i], times[i]);
delay(delays[i]);
}
noTone(SPEAKER);
}
void loop(){}