Skip to main content

How to use buttons

This guide shows you how to use the built-in buttons on the Codi:bit board to detect user input.

Prerequisites​

  • Basic understanding of Python
  • Codi:bit board
  • MicroPython environment set up

Button State Detection​

The Codi:bit button class provides three main methods for detecting different button states:

1. is_pressed() - Moment of Press Detection​

Detects the exact moment when a button is pressed (one-time event).

from codibit import *

while True:
    # Detect when Button A is pressed
    if button_a.is_pressed():
        print("Button A pressed!")

    # Detect when Button B is pressed
    if button_b.is_pressed():
        print("Button B pressed!")

    # Small delay for optimal performance
    sleep(0.01)

2. is_holding() - Continuous Press Detection​

Detects when a button is continuously being held down.

from codibit import *

while True:
    # Check if Button A is being held
    if button_a.is_holding():
        print("Button A is being held...")

    # Check if Button B is being held
    if button_b.is_holding():
        print("Button B is being held...")

    sleep(0.01)

3. is_released() - Moment of Release Detection​

Detects the exact moment when a button is released (one-time event).

from codibit import *

while True:
    # Detect when Button A is released
    if button_a.is_released():
        print("Button A released!")

    # Detect when Button B is released
    if button_b.is_released():
        print("Button B released!")

    sleep(0.01)

Complete Button State Monitoring​

You can monitor all button states simultaneously:

from codibit import *

while True:
    # Press detection
    if button_a.is_pressed():
        print("🔴 Button A: Pressed!")

    # Continuous holding
    if button_a.is_holding():
        print("🟡 Button A: Holding...", end='\r')

    # Release detection
    if button_a.is_released():
        print("🟢 Button A: Released!")

    sleep(0.01)

Counting Button Presses​

The get_presses() method returns the total number of button presses and resets the counter.

from codibit import *

print("Press buttons multiple times, then wait 5 seconds for count...")

while True:
    # Wait 5 seconds
    sleep(5)

    # Get the number of times Button A was pressed
    a_presses = button_a.get_presses()

    # Get the number of times Button B was pressed
    b_presses = button_b.get_presses()

    # Display the counts
    if a_presses > 0:
        print(f"Button A was pressed {a_presses} times")

    if b_presses > 0:
        print(f"Button B was pressed {b_presses} times")

Tracking Accumulated Button Presses​

The get_press_count() method returns the total accumulated number of button presses without resetting the counter.

from codibit import *

print("Press buttons to see real-time accumulated count...")

while True:
    # Get accumulated Button A press count
    total_a = button_a.get_press_count()

    # Get accumulated Button B press count
    total_b = button_b.get_press_count()

    # Real-time display
    print(f"\rTotal presses - A: {total_a}, B: {total_b}", end="")

    sleep(0.1)

get_presses() vs get_press_count() Comparison​

It's important to understand the difference between these two methods:

from codibit import *

print("Press buttons multiple times...")
sleep(3)

# First check
presses_a = button_a.get_presses()  # Counter is reset
count_a = button_a.get_press_count()  # Counter is not reset

print(f"get_presses(): {presses_a} (reset)")
print(f"get_press_count(): {count_a} (accumulated)")

sleep(2)

# Second check
presses_a2 = button_a.get_presses()  # 0 (already reset)
count_a2 = button_a.get_press_count()  # Still accumulated value

print(f"get_presses(): {presses_a2} (still 0)")
print(f"get_press_count(): {count_a2} (accumulated maintained)")

Advanced Button Patterns​

State-Based Button Handling​

Track button states for more complex interactions:

from codibit import *

button_a_pressed = False
counter = 0

print("Button A: increment, Button B: decrement")
print(f"Counter: {counter}")

while True:
    # Button A press detection
    if button_a.is_pressed():
        button_a_pressed = True
        counter += 1
        print(f"Counter: {counter}")

    # Button A release detection
    if button_a.is_released():
        button_a_pressed = False
        print("Button A released")

    # Button B press detection
    if button_b.is_pressed():
        counter -= 1
        print(f"Counter: {counter}")

    # Button B release detection
    if button_b.is_released():
        print("Button B released")

    sleep(0.01)

Simultaneous Button Detection​

Detect when multiple buttons are pressed at the same time:

from codibit import *

print("Press both buttons A and B together...")

while True:
    # Check if both buttons are being held simultaneously
    if button_a.is_holding() and button_b.is_holding():
        print("Both buttons are being held!")

    # Individual button press detection
    if button_a.is_pressed():
        print("Button A pressed")

    if button_b.is_pressed():
        print("Button B pressed")

    # Individual button release detection
    if button_a.is_released():
        print("Button A released")

    if button_b.is_released():
        print("Button B released")

    sleep(0.01)

Simple Menu System​

Create a basic menu system using buttons.

from codibit import *

menu_items = ["Start Game", "Settings", "Exit"]
current_item = 0

def show_menu():
    print(f"Menu: {menu_items[current_item]}")
    print("A: Select, B: Next")

# Show initial menu
show_menu()

while True:
    # Menu selection
    if button_a.is_pressed():
        print(f"Selected: {menu_items[current_item]}")
        sleep(1)
        show_menu()

    # Navigate menu
    if button_b.is_pressed():
        current_item = (current_item + 1) % len(menu_items)
        show_menu()

    sleep(0.01)

Tips and Best Practices​

1. Choose the Right Method​

  • is_pressed(): Detect the moment a button is pressed (one-time event)
  • is_holding(): Detect continuous button holding
  • is_released(): Detect the moment a button is released (one-time event)
  • get_presses(): Periodic counting with counter reset
  • get_press_count(): Real-time cumulative counting without reset

2. Performance Optimization​

Always include small delays in your loops:

sleep(0.01)  # 10ms - recommended for most cases
sleep(0.05)  # 50ms - for stability-focused applications

3. Button State Flow​

The typical button interaction flow:

  1. is_pressed() - Button is pressed
  2. is_holding() - Button is being held (continuous)
  3. is_released() - Button is released

4. Debouncing​

The buttons automatically handle debouncing with a 50ms delay. You can adjust this:

button_a = Button(BUTTON_A_PIN, debounce_ms=30)  # Faster response
button_b = Button(BUTTON_B_PIN, debounce_ms=100)  # More stable

5. Event Handling Best Practices​

# ✅ Good: Check all states in order
if button_a.is_pressed():
    print("Pressed!")

if button_a.is_holding():
    print("Holding...")

if button_a.is_released():
    print("Released!")

# ❌ Avoid: Missing state checks
if button_a.is_holding():  # Should check is_pressed() first
    print("Holding...")

6. Counter Management​

  • get_presses(): Resets counter, suitable for periodic counting
  • get_press_count(): Maintains counter, suitable for cumulative statistics

7. Memory Efficiency​

For MicroPython environments, use appropriate sleep intervals to balance responsiveness and CPU usage.