Input Devices

In this group assignment, we joined a group of colleagues from the academy to use an oscilloscope to demonstrate the signals generated by some electronic devices, observing and comparing the analog and digital signals generated by the sensors. This allowed us to discuss adjustments, optimize our implementations, and identify similarities and differences in the results. The instructors, Ulises and Roberto, showed us the function of electronics by testing input devices. The class was very clear and dynamic. I'm sharing the link so you can access this training. This class helps you understand the basic concepts of electronics and the tests that can be performed.

This week's topic is measuring input devices. For this, we attended a class taught by instructors Ulises and Roberto. This class was quite dynamic, as several measuring instruments, such as a multimeter, were used. Performing these measurements will help us understand several key concepts useful for the task.

• In this exercise we learned how to use code in MicroPython, using the Wokwi online simulator to blink an LED.

This is the code I used:

from machine import Pin
from time import sleep
				
print("Hello, Fab Academy 2025!")
				
pinLed = Pin(3, Pin.OUT)
				
while True:
	#pinled.toggle()
	pinLed.value(0)
	print("Apagado")
	sleep(1.0)
	pinLed.value(1)
	print("Encendido")
	sleep(1.0)												

For this exercise, we add a push button to the circuit shown in exercise 1, which controls the LED turning on and off.

This is the code I used:

											
from machine import Pin
from time import sleep

print("Hello, Fab Academy 2025!")

pinLed = Pin(3, Pin.OUT)
pinBut = Pin(26, Pin.IN)

while True:
    print(pinBut.value())
   	pinLed.value(pinBut.value())
    sleep(0.5)

For this exercise, we worked with the XIAO ESP32-C3 microcontroller and the MPU6050, a sensor that combines a 3-axis accelerometer and gyroscope in a single chip. It is used to measure acceleration, angular velocity, and 6-degree-of-freedom motion. The MPU6050 communicates via the I2C interface.

#include 
#include 
													
MPU6050 mpu;
													
// Variables para inclinación
float anguloX, anguloY;
unsigned long tiempoPrev;
float dt;
													
void setup() {
  Serial.begin(115200);
  Wire.begin();
  mpu.initialize();
													  
  if (mpu.testConnection()) {
  Serial.println("MPU6050 conectado correctamente");
  } else {
  Serial.println("Error al conectar MPU6050");
  while (1);
  }
													  
  // Calibración inicial (dejar el sensor quieto 3 segundos)
  Serial.println("Calibrando... No muevas el sensor");
  delay(3000);
  tiempoPrev = millis();
  }
													
void loop() {
  // Leer datos del giroscopio y acelerómetro
  int16_t ax, ay, az, gx, gy, gz;
  mpu.getMotion6(&ax, &ay, &az, &gx, &gy, &gz);
													  
  // Calcular intervalos de tiempo
  dt = (millis() - tiempoPrev) / 1000.0;
  tiempoPrev = millis();
													  
  // Convertir a valores útiles
  float aceleracionX = ax / 16384.0; // Escala ±2g
  float aceleracionY = ay / 16384.0;
  float giroX = gx / 131.0;         // Escala ±250°/s
  float giroY = gy / 131.0;
													  
  // Calcular ángulos de inclinación (filtro complementario)
  anguloX = 0.98 * (anguloX + giroX * dt) + 0.02 * atan2(aceleracionY, sqrt(aceleracionX * aceleracionX + az / 16384.0 * az / 16384.0)) * 180 / PI;
  anguloY = 0.98 * (anguloY + giroY * dt) + 0.02 * atan2(aceleracionX, sqrt(aceleracionY * aceleracionY + az / 16384.0 * az / 16384.0)) * 180 / PI;
													  
  // Mostrar resultados en Serial
  Serial.print("Inclinación X: "); Serial.print(anguloX); Serial.print("° | ");
  Serial.print("Y: "); Serial.print(anguloY); Serial.println("°");
													  
  Serial.print("Giro X: "); Serial.print(giroX); Serial.print("°/s | ");
  Serial.print("Y: "); Serial.print(giroY); Serial.println("°/s");
													  
  Serial.println("---------------------");
  delay(200); // Ajusta este delay para mayor/menor frecuencia de lectura
}
												

The DHT11 sensor combines temperature and humidity in a compact design. It measures temperatures from 0°C to 50°C with an accuracy of ±2°C and relative humidities from 20% to 90% with an accuracy of ±5%. Thanks to its low sampling rate, the sensor only provides new readings every two seconds, making it ideal for long-term measurements. The DHT11 is easy to integrate into microcontroller platforms such as Arduino and Raspberry Pi and requires no additional calibration thanks to its factory calibration. Its robust design and reliability make it the ideal choice for continuous monitoring projects such as greenhouses, HVAC systems, and warehouse monitoring.

This is the code I used:

const int DHpin = 2;  // Usa GPIO2 (ajústalo según tu conexión)
byte dat[5];          // Almacena datos [hum_ent, hum_dec, temp_ent, temp_dec, checksum]

void setup() {
  Serial.begin(115200);
  pinMode(DHpin, OUTPUT);
  digitalWrite(DHpin, HIGH);  // Inicia el bus en alto
}

byte read_data() {
  byte result = 0;
  for (int i = 0; i < 8; i++) {
    while (digitalRead(DHpin) == LOW);  // Espera hasta que el pin esté alto
    delayMicroseconds(30);              // Duración crítica para distinguir 0/1
    
    if (digitalRead(DHpin) == HIGH)     // Si sigue alto después de 30us, es un 1
      result |= (1 << (7 - i));         // Almacena el bit (MSB first)
    
    while (digitalRead(DHpin) == HIGH); // Espera a que termine el bit
  }
  return result;
}

void start_test() {
  // 1. Envía señal de inicio
  digitalWrite(DHpin, LOW);
  delay(20);                      // >18ms para DHT11 (no 30ms para evitar timeouts)
  digitalWrite(DHpin, HIGH);
  delayMicroseconds(40);          // Espera respuesta
  
  // 2. Configura el pin como entrada y espera respuesta
  pinMode(DHpin, INPUT);
  while (digitalRead(DHpin) == HIGH);  // Espera a que DHT11 ponga LOW
  delayMicroseconds(80);               // LOW durante 80us (respuesta)
  
  // 3. Lee los 40 bits de datos (5 bytes)
  for (int i = 0; i < 5; i++) 
    dat[i] = read_data();
  
  // 4. Finaliza la comunicación
  pinMode(DHpin, OUTPUT);
  digitalWrite(DHpin, HIGH);
}

void loop() {
  start_test();
  
  // Verifica checksum
  byte checksum = dat[0] + dat[1] + dat[2] + dat[3];
  if (dat[4] != checksum) {
    Serial.println("Error de checksum!");
    return;
  }
  
  // Imprime datos
  Serial.print("Humedad: ");
  Serial.print(dat[0]);  // Parte entera humedad
  Serial.print(".");
  Serial.print(dat[1]);  // Parte decimal humedad
  Serial.println("%");
  
  Serial.print("Temperatura: ");
  Serial.print(dat[2]);  // Parte entera temperatura
  Serial.print(".");
  Serial.print(dat[3]);  // Parte decimal temperatura
  Serial.println("°C");
  
  delay(2000);  // Espera 2 segundos entre lecturas
}
											

The KY-031 module is better known as the Impact Sensor. This sensor is capable of detecting impacts that it or a surface attached to it may receive.

It operates as a normally open contact, sending a logic "1" through its signal terminal the instant it receives physical contact.

This is the code I used:

const int Shock = 2;  // KY-031 en GPIO2

int val;              // Variable para leer el sensor

void setup() {
  pinMode(Shock, INPUT);
  Serial.begin(115200);
}

void loop() {
  val = digitalRead(Shock);
  
  if(val == HIGH) {
    Serial.println("GOLPE REAL");  
    delay(100); 
  }
  else {
    Serial.println("sin golpe");  
    delay(100); 
  }
}
											

in In this video you can see that the sensor emits a digital signal: HIGH when it does not detect an impact and LOW when it detects a blow