Week 9. Output devices

Group assignment

Tasks

Our group assignment page

• measure the power consumption of an output device

we tried three methods.

• with power supply
• with power supply and multimeter
• with Arduino + simulation

Individual assignment

For output devices I decided to use a water pump which will be useful for my final project. I’ve found some pumps and ultrasound fog maker.

After trying the fog maker with power supply I find out it works starting with 11V to 24V. I was given a 24 V power supply. And I wanted to modulate the power of this device with transistor.

! UNFINISHED

Transistor with LED

I tried to use a transistor. What I found is IRFZ44N mosfet transistor and I observed it’s datasheet.

I connect the gate with a digital pin on my Quentorres.

gate is powered by pin 1, which we can see is also turning on/off the LED on the board. And when it delays 5 seconds HIGH the transistor lets the LED on the breadboard to light.

ResultArduino code

And when I unplug the gate pin, LED gets powered from board and lights up. And when I plug the gate pin back, the transistor gets 3.3V and opens chain to provide power the LED.

code I took is simple pin toggle example

      #define pin 1

    void setup() {
      // put your setup code here, to run once:
      pinMode(pin, OUTPUT);

    }

    void loop() {
      // put your main code here, to run repeatedly:
      digitalWrite(pin, 1);
      delay(5000);
      digitalWrite(pin, 0);
      delay(5000);

    }

Servo motor

CS-939MG servo motor is what tried as an output device.

First, I tried to adjust rotation angle with Arduino code.

Servo motorArduino code

I opened example code for sweep on Arduino.

    #include <Servo.h>

    Servo myservo;  // create servo object to control a servo
    // twelve servo objects can be created on most boards


    void setup() {
      myservo.attach(1);  // attaches the servo on 1 pin to the servo object
    }

    void loop() {
      int pos;

      for (pos = 0; pos <= 180; pos += 1) { // goes from 0 degrees to 180 degrees
        // in steps of 1 degree
        myservo.write(pos);              // tell servo to go to position in variable 'pos'
        delay(15);                       // waits 15ms for the servo to reach the position
      }
      for (pos = 180; pos >= 0; pos -= 1) { // goes from 180 degrees to 0 degrees
        myservo.write(pos);              // tell servo to go to position in variable 'pos'
        delay(15);                       // waits 15ms for the servo to reach the position
      }
    }

---

Potentiometer

Then I tried to use with potentiometer

Servo motorArduino code

I used this scheme that I’ve found on Internet. It’s using Arduino board but I changed pins and used the RP2040 same way. I Connected the potentiometer to A0 analog pin and remaining pins same as in the scheme.

#include <Servo.h>

Servo servo1;  
int potin;    

void setup()
{
  servo1.attach(2); 
}

void loop() 
{ 
  potin = analogRead(A0);            
  potin = map(potin, 0, 1023, 0, 180);    
  servo1.write(potin);                  
  delay(15);   
}

Servo tester

Additionally I used servo tester device to check it’s angular limits. it varies from 800 to 2200 values, which are from 0 to maximum posible angle o this servo.

Store page for this Servo tester HJ speed controller Tester for brushless servos 2X3 1-4 Servos / ESC.

Conclusion

This week I used few outpud devices and tried to conntrol them with using PWM on my microcontroller and transistor.

I used

• Ultrasound fog maker
• LED and transistor
• Servo motor with and without potentiometer.