Output Devices¶

Group assignment

Measure the power consumption of an output device.
Document your work on the group work page and reflect on your individual page what you learned.

Individual assignment

Add an output device to a microcontroller board you’ve designed and program it to do something.

Learning outcomes

Demonstrate workflows used in controlling an output device(s) with MCU board you have designed.

Have you answered these questions?

Linked to the group assignment page.
Documented how you determined power consumption of an output device with your group.
Documented what you learned from interfacing output device(s) to microcontroller and controlling the device(s).
Linked to the board you made in a previous assignment or documented your design and fabrication process if you made a new board.
Explained the programming process/es you used.
Explained any problems you encountered and how you fixed them.
Included original source code and any new design files.
Included a ‘hero shot’ of your board.

Time Management¶

You can access my timetable here.

Group assignment¶

You can access the link to my group assignment here.

It’s week 10 😱!! For this week’s group assignment, it required us to measure the power consumption of an output device.

Power consumption¶

Power consumption is the rate at which energy is consumed by a device and is commonly measured in watts (W) or milliwatts (mW). It is a very crucial part of determining the energy efficiency and performance of electrical or electronic devices.

To measure the power consumption of an output device, we will be using a multimeter. With the use of a multimeter, we will be able to find out its voltage and current, from which we will be able to derive its power from the formula below.

Power (in watts, W) = Voltage (V) × Current (A)

Power Consumption of an LED¶

For the week’s group assignment, we will be measuring the power consumption of an LED.

Components required¶

Multimeter with an Ammeter function
Power source (such as a battery or power supply)
LED setup (LEDs, resistors, and connecting wires)

Lets set up the componets now!

Voltage consumption¶

To measure the voltage, the multimeter probes must be connected parallel to the circuit. Make sure to turn the multimeter dial to DC Voltage (⎓ V or just V with straight and dotted line). Connect the negative(black) probe to the Red probe ground and the positive(red) probe to the positive side of the device.

Here are the results, which is 5.03 Volts.

You can also measure the volatge consumption between the resistor and the LED individually as well, which should add to give a sum of the overall voltage of the circuit which is 5.03 volts.

To measure the voltage of the resistor, just place the multimeter probes between the 2 points of the resistor. It gives a result of 3.14 volts.

Do the same with the LED. It is giving 1.89 volts.

1.89 + 3.14 = 5.03

From here, we can confirm that the results we got for the overall voltage of the circuit is true.

Current consumption¶

To measure the current consumption, we must connect the multimeter probes in serial connection, meaning the multimeter must be a part of the circuit.

The result we got is 12.42 mA (or 0.01242 A).

Result¶

Now we work just put the values in the formula and calculate!

Voltage (V) × Current (A) = Power

5.3V × 0.01242A = ~0.0658 W (or ~66 mW)

Reflection¶

We were able to learn a lot through this assignment. We faced a lot of difficulties in measuring the voltage and current in the beginning due to some issues with out multimeter so we had to switch it up. By learning how to measure the power consumption of our output devices, it will help us while working with our final project components as well.

Individual assignment¶

This week’s assignment required us to program an output device to the board we designed during the earlier weeks and make it do something. For this, I am using the board I designed in Week 8. To learn more about it, you can go through this link.

This is the PCB layout of my board.

I chose to program a servo motor and our Fab Guru, Mr. Rico helped a LOT. I am very grateful to him!

Suggestions¶

We had a zoom call with Mr. Rico, and there was a lot of suggestions he had provided me with, regarding my board. Here are some of them:

He suggested that I don’t leave the pins unconnected, especially the TX, RX, SDA, and SCL pins. He mentioned that it will come in handy in the future.
He also suggested that I connect an LED to each and every board I make in the future, to make sure that I can properly test if it is working or not.

Blink code¶

None of my codes were working with any of my Arduino IDE, so I decided to check it with the blink code.

First, we need to check if our LED is working or not. Keep your multimeter on the following setting. Make sure the symbol on the top of the display appears because it will not work otherwise. We had to learn that the hard way😔

Now you can connect wires to the legs of the LED and bring it to the multimeter probes. If it is glowing, it means that the LED is working.

Checking the resistance of the resistor

We can also use the multimeter to check the resistance of the resistor. To do so, keep the setting of the multimeter the same as before and connect the multimeter probes to each of the legs of the resistor without it touching itself.

Here, you can see that the resistance is almost 1kΩ, which is good.

After confirming that the LED is working perfectly fine, I uploaded the blink code to my board connected to my LED. This confirmed that my board is working just fine. Thank you Rico!

To learn how to upload the blink code from the very basics, you can go through my documentation for week 8.

Servo motor¶

Now, let’s connect a servo motor to my board. For reference, this is the pinout of a servo motor.

We need to donwload the library of it first.

Important learning!¶

After downloading a library for servo motors and uploading one of its in-built code, it gave me this error.

It was then that we learnt that for a servo motor to be programmed in an ESP32 microcontroller, a sepecific library is required. That is why we donwloaded this library, specifically built for an ESP32 MCU.

This is the code I used that Mr. Rico provided.

#include <ESP32Servo.h>

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

int pos = 0;    // variable to store the servo position

void setup() {
  tsheyang_servo.attach(2);  // attaches the servo on pin 9 to the Servo object
}

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

Code Explaination¶

The code starts off by importing the ESP32Servo library and creating the servo object named tsheyang_servo. In the setup function, it declares that the servo is connected to GPIO 2 of my board.

Inside the loop function, it moves the servo from 0° to 180° forward and from 180° to 0° backwartds. It uses the function myservo.write(pos); to set the the position to 0. delay(15); delays the movement by 15 milliseconds for smoother transition. Basically, the code allows the servo motor to sweep back and forth continuously.

Results¶

Heroshots¶

Files¶

Code for Servo Motor

Thank you!

The template for this website was provided by Mr. Anith Ghalley and used with his permission

Last update: April 6, 2025