Week 09 — Input Devices: probing analog and digital signals

During the input devices week, the group explored how to read and measure analog and digital electrical signals using three different tools: a digital multimeter, a portable oscilloscope, and the Arduino IDE Serial Monitor.

Multimeter measurements on a button circuit

We built a simple circuit on a breadboard with a tactile button, a green LED, and a 2kΩ resistor, powered at 5V/2A. We identified four measurement points — A, B, C, D — and measured the voltage between each one with a CHY A830L digital multimeter.

Breadboard annotated with measurement points Notebook with voltage measurements

Segment	Voltage
A	5.40 V
A → B	2.96 V
B → C	2.38 V
C → D	3.36 V

Oscilloscope on the button (digital signal)

We connected a portable oscilloscope to the button to visualize the digital signal. When the button is released the trace is flat at the bottom; when pressed it rises sharply. The transition is clean and clearly visible at the 2mS scale.

Oscilloscope — button not pressed, flat signal Oscilloscope — button pressed, signal at 2280mV

Potentiometer with multimeter and Barduino

Following the instructions projected in class, we connected a blue potentiometer to the Barduino (ESP32-S3): one pin to 3.3V, one to GND, and the center pin to an analog pin. The DT321B multimeter confirmed the supply voltage at 3.31–3.32V.

Class instructions on screen Circuit diagram on screen — I=V/R Barduino with potentiometer on breadboard Multimeter reading 3.31V Multimeter reading 3.32V Multimeter reading 3.32V — second angle Oscilloscope connected to potentiometer

Serial Monitor — analogRead in real time

With the potentiometer connected to pin A1 of the ESP32-S3, we uploaded a minimal sketch that reads the analog value every 200ms and prints it to the Serial Monitor. Rotating the potentiometer changes the value in real time between 0 and 4095 (12-bit ADC). The video shows the value at 3405.

int potPin = A1;
int potValue = 0;

void setup() {
  Serial.begin(115200);
}

void loop() {
  potValue = analogRead(potPin);
  Serial.println(potValue);
  delay(200);
}