Input Devices

Reading data from an input device and documenting the full workflow in Fab Academy style: device selection, datasheet review, wiring, code, testing, and results.

Assignment

Input Devices

Board

ESP32-C3 SuperMini

Sensor

Sparkfun OLE i2c Screen & Others

Output

Measured input data

Goal: Connect and read an input device, then verify that the board can receive and process real input data.

What I have used is i2c Sparkfun OLE Transparent screen with Tempreature (BMP280) and Ultrasonic (HC-SR04) to connect them to ESP32-C3 and read various data from each on of them then display them on the ic2 screen.

🧠 Learning Objectives

Understand how an input device communicates with a microcontroller.
Read and interpret sensor or switch data correctly.
Document wiring, code, and validation results clearly.

📌 FabLab Documentation Requirements (Checklist)

Show the full workflow

Sensor choice, datasheet notes, wiring, code, and testing.
Document technical details

Operating voltage, communication protocol, pin usage, and measured readings.
Include evidence

Photos/screenshots of wiring, serial monitor, graph, or sensor response.
Provide source files

Code, notes, and any diagrams or design files used.

🛠️ Tools & Materials

Microcontroller Board: ESP32-C3 SuperMini Board
Input Device: Temperature sensor (BMP280), ultrasonic sensor (HC-SR04), Sparkfun Transparent OLE
Software: Arduino IDE
Testing Tools: Serial Monitor, multimeter
Other Materials: breadboard, jumper wires, resistors, USB cable

Selection note: I chose this input device because it is relevant to my final project / it allowed me to understand analog or digital input behavior.

🎛️ Chosen Input Device

For this assignment, I used a Ultrasonic (HC-SR04). This device is used to measure distance and shows it on the OLE.

Type: Digital / Analog / I2C
Main function: the Ultrasonic measures how far an object on my blind-spot and then display arrow on the OLE to warn me of an object behind me!
Why I chose it: Its required when wearing a helmet as I can't see blind-spots behind me!

Input device photo — Photo of the selected input device.

Close-up of sensor pins — Close-up showing pins and labels on the sensor module.

📄 Datasheet Review

Before connecting the device, I reviewed the datasheet to understand the most important technical parameters.

Operating Voltage	3.5v to 5v	Ensures safe connection to the board
Output Type	Digital Pulse Width (TTL)	Determines how the board reads the signal
Current Consumption	~15 mA	Helps verify power requirements
Pin Description	VCC: 3.5v to 5v	Trig: Input pin. Set high for 10μs to trigger the ultrasonic pulse	Echo: Output pin. Outputs a high-level signal proportional to the time taken for the sound to return	GND: Ground connection (0V).	Needed for correct wiring

Focus: I mainly checked voltage, pinout, communication type, and any restrictions or calibration notes.

🔌 Wiring & Connections

I connected the input device to the board according to the datasheet and verified the signal path before programming.

VCC → board power pin 3.5v
GND → board ground pin GND
Trig/Data → selected GPIO pin 0
Echo pins → selected GPIO pin 1

Wiring overview of board and sensor — Full wiring setup between the board and the input device.

💻 Code

// Example: reading a digital input device
#include 
#include 
#include 
#include 

float vDistance = 0;

//Used a library to read the Ultrasonic
AfstandsSensor afstandssensor(0, 1); //Pin 0=Trig & Pin 1=Echo

void getDistance() {
  Serial.println(afstandssensor.afstandCM());
  vDistance = afstandssensor.afstandCM();
}

void loop() {
  getDistance();
  Serial.println ("Distance = " + vDistance);
}

The code continuously reads the device value and sends it to the serial monitor so I can validate how the input changes over time.

🧪 Testing Process

Uploaded the code to the board.
Opened the Serial Monitor to observe live input values.
Interacted with the device physically or changed its environment.
Compared the observed readings with the expected behavior.

Validation method: I checked whether the sensor values changed correctly when the input condition changed.

✅ Results

Serial monitor showing input readings — Serial Monitor output showing live input readings.

Testing the sensor or input device — Testing the input device during operation.

Test Condition	Expected Result	Observed Result
Condition 1	Value changes to X	Success / Replace with actual result
Condition 2	Value changes to Y	Success / Replace with actual result
Stability check	Consistent readings	Replace with actual result

⚠️ Issues & Fixes

No readings: checked wiring, power, and correct GPIO pin.
Unstable values: reviewed grounding, pull-up/pull-down configuration, or filtering.
Wrong communication: verified baud rate / protocol / library usage.
Unexpected values: revisited the datasheet and confirmed calibration or scaling formula.

📦 Links & Files

Code File Wiring Diagram Datasheet Link

Reflection — What I Learned

Reading datasheets first makes wiring and coding much easier.
Understanding whether a device is analog or digital affects how it should be programmed.
Live testing with the Serial Monitor is essential for verifying behavior.
Documenting readings and conditions helps compare expected vs actual results clearly.

Lab Assignment

Todays assignment was to read an input device and measure the data with Osciliscope. Since I we don't have Osciliscope within the lab at home, I used online Osciliscope from site (Falstad.com). I added input source of 5V, Resistor of value 10k and LED.

We noticed that when increasing the Resistor value from 1K to 10K the LED light dims as the current flowing from the 5V source has been dropped low to what the LED requires to light-up!!