Week 10

This is my 10th week at FabAcademy. This week was really intense, and as usual, I have learnt a lot. The hero shot of the week is without any doubt my new PCB design working with a servo and oled. I believe it is a great advance, because apart from the advancement of the week itself, I could greatly refine and achieve a PCB that it is quite close to the one I will need in the final project. Below I explain the details about that.

Heroshot: My new PCB design working and including my two outputs, servo and OLED

But, before, lets recall the assignment of the week 10, which consisted of:

group assignment: measure the power consumption of an output device individual assignment: add an output device to a microcontroller board you’ve designed, and program it to do something

Group assignment

Regarding the group assignment, we were measuring the power consumption of several devices that relate to our final projects, including a LED strip, the XIAOESP32C3 without peripherials and and microcontroller including peripherials such as an OLED screen, check out the details of the power consumption measurments here https://fabacademy.org/2025/labs/aindustriosa/week10.html.

Individual assignment

Regarding the individual assignment, I realized that my old PCB was experiencing some troubles and also that it was not well prepared for this second term of the FabAcademy, so I decided to hard-work on the idea of the PCB necessary for my final project and developed a completely new desing. In summary, for my final project I will need a series of input devices, including 2 temprerature + moisture sensors, one ambient light sensor, and one external solar power device. Regarding output devices, I will need an OLED screen and two servos. Therefore, considering all the existing material an future purchases, I designed a new board. Here you can see the schematic of the PCB:

And here you can see the PCB board after tracking, adding bridging resistances and personalizing the design:

And here, after some working, you can see the milling traces in VCarve prior to CNC-machining in our old but nice Roland machine

Here, you can see the final result of my newly designed and fabricated PCB:

As well as the sequence for preparing and soldering the components

Once, the board was ready, I started to think about outputs. In my case I will need two outputs: servos and OLED screen, therefore I decided to work with both during this week. First, I started working with the servos. I checked several tutorials in the internet, and this one was very good https://www.luisllamas.es/esp32-servo/ in there it is explained in detail diferent ways of controlling a servo in a ESP32 microcontroller. Based on that tutorial I worked on my first code, which was intended for just generating a simple oscilatory move of the servo, the code read as follows

#include <ESP32Servo.h> // library necessary for running the servo

Servo myServo; // create my servo

const int pinServo = D7; // number of pin for the servo

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

void loop() 
{
  myServo.write(0);    // Move servo to 0 degrees
  delay(1000);         // Wait 1 s
  myServo.write(90);   // Move servo to 90 degrees
  delay(1000);         // Wait 1 s
  myServo.write(180);  // Move servo to 180 degrees
  delay(1000);         // Wait 1 s
}

In order to run this code, it is necessary to install the ESP32Servo library in Arduino, here you can see the details of the version I installed

This worked fine, here you can see my PCB controlling the oscilatory movement of the servo, by the way, I used the servo we had in our inventory, which is a MG90S servo:

Once the servo was accomplished, I started working with the OLED screen. In this excercise, I decided to develop a program that, using as basis the simple oscilatory movement of the servo, the Screen and syncronically ploting the angle of servo rotation. Having in my case a 0,96" wide OLED screen, the code consisted of the following

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <ESP32Servo.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET    -1
#define SCREEN_ADDRESS 0x3C

#define SDA_PIN D4
#define SCL_PIN D5

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
Servo myServo;
const int pinServo = D7;
int angle = 0; // Variable for storing real-time angle

void setup() {
    Wire.begin(SDA_PIN, SCL_PIN);
    myServo.attach(pinServo);
    
    if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
        for (;;);
    }
    display.clearDisplay();
}

void loop() {
    int angles[] = {0, 90, 180};
    for (int i = 0; i < 3; i++) {
        angle = angles[i];
        myServo.write(angle);
        
        // Refresh OLED screen
        display.clearDisplay();
        display.setTextSize(2);
        display.setTextColor(SSD1306_WHITE);
        display.setCursor(10, 20);
        display.print("Angle: ");
        display.print(angle);
        display.print((char)247); // degree symbol
        
        display.display();
        delay(1000);
    }
}

In order to run that code in Arduino, apart from the aforementioned library for the servo, it is necessary to install the Adafruit_GFX and Adafruit_SSD1306 libraries, but in my case I already installed them in previous excercises. Here you can see the servo and OLED screen working sincornically and the two main outputs of my project idea:

Files for download and replication

Here you can download the PCB files including all Kicad files, svgs and VCarve file PDB_design, here you can download the code for the servo moving (first output excercise) servo_oscillation as well as the Arduino IDE file for the OLED+plus servo outputs OLED_Servo.

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