💡 Level 1 – Fundamentals

Project 1.7: "Digital Sensors"

🚀 Project 1.7 – Digital Sensors

🎯 What You’ll Learn

✅ Goal 1: Read button states.
✅ Goal 2: Control LEDs and motors with button input.
✅ Goal 3: Handle bouncing and create counters.

Key Ideas

Digital input: Detect HIGH/LOW from a button.
Digital output: Control LEDs or motors.
Logic: Use button state to trigger actions.

🧱 Blocks Glossary (used in this project)

pinX = machine.Pin(X, machine.Pin.IN) → Button input.
pinX = machine.Pin(X, machine.Pin.IN, machine.Pin.PULL_UP) → Button input with pull‑up.
pinX = machine.Pin(X, machine.Pin.OUT) → LED or motor output.
pinX.value() → Read pin state.
pinX.value(1) → Set pin HIGH (ON).
pinX.value(0) → Set pin LOW (OFF).
while True: → Infinite loop.
time.sleep() → Delay.

🧰 What You Need

Part	How many?	Pin connection
D1 R32	1	USB cable
Push Button	2	Pin 2, Pin 4
LED	1	Pin 5

🔌 Wiring tip: Connect button one to pin 2, button two to pin 4, LED to pin 5.
📍 Pin map snapshot: Pin 2/4 = buttons, Pin 5 = LED.

✅ Before You Start

USB cable connected
Buttons wired correctly
Test print shows:

print("Ready!")  # Confirm serial is working

🎮 Microprojects (5 Mini Missions)

🎮 Microproject 1.7.1 – Reading button status

Blocks used: Digital input, Serial print
Block sequence:

Setup button pin as input
Read value
Print state

MicroPython Code:

import machine, time                          # Import modules

pin2 = machine.Pin(2, machine.Pin.IN)         # Pin 2 as input for button

while True:                                   # Infinite loop
    state = pin2.value()                      # Read button state (0 or 1)
    print("Button state:", state)             # Serial log of button state
    time.sleep(0.5)                           # Delay for readability

Reflection: Button state is read continuously.
Challenge: Try changing the pin to 4 for the second button.

🎮 Microproject 1.7.2 – Button‑controlled LED

Blocks used: Digital input, Digital output
Block sequence:

Setup button pin as input
Setup LED pin as output
If button pressed → LED ON

MicroPython Code:

import machine, time                          # Import modules

pin2 = machine.Pin(2, machine.Pin.IN)         # Pin 2 as input for button
pin5 = machine.Pin(5, machine.Pin.OUT)        # Pin 5 as output for LED

while True:                                   # Infinite loop
    if pin2.value() == 1:                     # If button pressed
        pin5.value(1)                         # Turn LED ON
        print("LED ON")                       # Serial log
    else:                                     # If button not pressed
        pin5.value(0)                         # Turn LED OFF
        print("LED OFF")                      # Serial log
    time.sleep(0.2)                           # Delay for stability

Reflection: LED responds to button press.
Challenge: Add a second button to control LED OFF.

🎮 Microproject 1.7.3 – Heart rate counter

Blocks used: Digital input, Counter, Serial print
Block sequence:

Setup button pin as input
Count presses
Print count

MicroPython Code:

import machine, time                          # Import modules

pin2 = machine.Pin(2, machine.Pin.IN)         # Pin 2 as input for button
count = 0                                     # Initialize counter

while True:                                   # Infinite loop
    if pin2.value() == 1:                     # If button pressed
        count += 1                            # Increase counter
        print("Heart rate count:", count)     # Serial log of count
        time.sleep(0.5)                       # Delay to avoid double count

Reflection: Button press increments counter.
Challenge: Try counting for 10 seconds and calculate beats per minute.

🎮 Microproject 1.7.4 – Anti‑bounce software

Blocks used: Digital input, Delay
Block sequence:

Setup button pin as input
Add delay after press
Prevent multiple counts

MicroPython Code:

import machine, time                          # Import modules

pin2 = machine.Pin(2, machine.Pin.IN)         # Pin 2 as input for button
count = 0                                     # Initialize counter

while True:                                   # Infinite loop
    if pin2.value() == 1:                     # If button pressed
        count += 1                            # Increase counter
        print("Count:", count)                # Serial log
        time.sleep(0.3)                       # Delay prevents bouncing

Reflection: Delay reduces false counts.
Challenge: Try adjusting delay to 0.1s or 0.5s.

🎮 Microproject 1.7.5 – Motor control with button

Blocks used: Digital input, Digital output, PWM
Block sequence:

Setup button pin as input
Setup motor pins as output + PWM
If button pressed → Motor ON

MicroPython Code:

import machine, time                          # Import modules

pin2 = machine.Pin(2, machine.Pin.IN)         # Pin 2 as input for button
pin12 = machine.Pin(12, machine.Pin.OUT)      # Motor IN3 output
pin13 = machine.Pin(13, machine.Pin.OUT)      # Motor IN4 output
pwm14 = machine.PWM(machine.Pin(14))          # Motor ENB PWM

pwm14.freq(2000)                              # Set PWM frequency
pwm14.duty(0)                                 # Start with motor OFF

while True:                                   # Infinite loop
    if pin2.value() == 1:                     # If button pressed
        pin12.value(1)                        # Motor forward IN3 HIGH
        pin13.value(0)                        # Motor forward IN4 LOW
        pwm14.duty(512)                       # Motor speed 50%
        print("Motor ON")                     # Serial log
    else:                                     # If button not pressed
        pwm14.duty(0)                         # Motor OFF
        print("Motor OFF")                    # Serial log
    time.sleep(0.2)                           # Delay for stability

Reflection: Button press controls motor.
Challenge: Add second button to reverse motor direction.

✨ Main Project – Digital Sensors

🔧 Blocks Steps (with glossary)

Digital input: Read button state.
Digital output: Control LED or motor.
Logic: Use button state for actions.

Block sequence:

Setup pins for buttons and outputs.
Read button state.
Control LED or motor.
Add counter and anti‑bounce.

MicroPython Code (mirroring blocks):

# Project 1.7 – Digital Sensors

import machine, time                          # Import required modules

pin2 = machine.Pin(2, machine.Pin.IN)         # Pin 2 input for button
pin5 = machine.Pin(5, machine.Pin.OUT)        # Pin 5 output for LED

count = 0                                     # Initialize counter

while True:                                   # Infinite loop
    if pin2.value() == 1:                     # If button pressed
        pin5.value(1)                         # LED ON
        count += 1                            # Increase counter
        print("LED ON, Count:", count)        # Serial log
        time.sleep(0.3)                       # Anti‑bounce delay
    else:                                     # If button not pressed
        pin5.value(0)                         # LED OFF
        print("LED OFF")                      # Serial log
        time.sleep(0.1)                       # Short delay

📖 External Explanation

This project shows how to use buttons as digital sensors.

Inputs detect button presses.
Outputs respond with LEDs or motors.
Counters and delays handle bouncing and measure events.
By combining these, students learn how sensors trigger actions in robotics.

✨ Story Time

Imagine your robot as a game controller 🎮. Each button press lights up an LED, starts a motor, or counts a heartbeat. With anti‑bounce, the robot avoids mistakes and responds smoothly, just like a professional device.

🕵️ Debugging (2 Common Problems)

🐞 Debugging 1.7.A – Inverted button state

Problem: Button reads pressed when it is not pressed.
Clues: Pull‑up or pull‑down resistor not set correctly.
Broken code:

pin2 = machine.Pin(2, machine.Pin.IN)         # Input without pull-up/down

Fixed code:

pin2 = machine.Pin(2, machine.Pin.IN, machine.Pin.PULL_UP)  # Correct pull-up

Why it works: Adding a pull‑up ensures the button reads HIGH only when pressed.
Avoid next time: Always check if your button wiring requires pull‑up or pull‑down.

🐞 Debugging 1.7.B – Uncontrolled rebounds

Problem: Button press counts multiple times.
Clues: Mechanical bounce causes repeated signals.
Broken code:

if pin2.value() == 1:
    count += 1
    print("Count:", count)

Fixed code:

if pin2.value() == 1:
    count += 1
    print("Count:", count)
    time.sleep(0.3)   # Anti-bounce delay

Why it works: Adding a short delay filters out bounce signals.
Avoid next time: Always include anti‑bounce logic when counting button presses.

✅ Final Checklist

Button state read correctly.
LED controlled by button.
Counter increments with presses.
Anti‑bounce implemented.
Motor controlled by button.

📚 Extras

🧠 Student tip: Try combining two buttons—one for ON and one for OFF.
🧑‍🏫 Instructor tip: Demonstrate bounce by showing rapid counts without delay.
📖 Glossary: Digital input, pull‑up, bounce, counter.
💡 Mini tip: Always test button state with print() before connecting to outputs.