2-Digit 7-Segment Counter Using Raspberry Pi Pico with Buttons and Buzzer

Ever wanted your project to go tik-tik as it counts? In this fun electronics project, we’ll build a 2-digit up/down auto counter using a Raspberry Pi Pico, two 7-segment displays, buttons for control, and even a buzzer that beeps with every count!

Perfect for school students, beginners, or hobbyists exploring MicroPython, displays, and sound.

🎯 What You’ll Learn

✅ Interface 7-segment displays
✅ Use buttons to control GPIO inputs
✅ Use a buzzer to generate tik-tik sounds
✅ Control timing and logic in MicroPython
✅ Understand multiplexing and PWM

A running auto-counter — meaning:

✅ Press Start-Up → it starts counting automatically every second
✅ Press Start-Down → it counts down every second
✅ Press Stop → it pauses
✅ Press Reset → goes back to 00

🧠 How It Works:

Feature	What It Does
`mode = "up"`	Starts incrementing counter automatically every second
`mode = "down"`	Starts decrementing every second
`mode = None`	Pauses (used in Stop or Reset)
`utime.ticks_diff()`	Waits 1000ms (1 sec) before next update
`display_digit(...)`	Uses multiplexing to show both digits smoothly

🧰 Components Needed

Component	Quantity
Raspberry Pi Pico	1
7-Segment Display (Common Cathode)	2
Push Buttons	4
Passive Buzzer	1
220Ω resistors (for segments/buzzer)	As needed
Jumper Wires + Breadboard	1 set

📌 Button Functions

Button	Action	GPIO
Start Up	Auto count upward	GP10
Start Down	Auto count downward	GP11
Reset	Set counter to 00	GP12
Stop	Pause counter	GP13

🔌 Buzzer Connection

Buzzer Pin	Connect To
+	GP15 (via 220Ω)
–	GND

We’re using a passive buzzer so we can control the frequency for different tones.

🔢 Segment to GPIO Pin Mapping

Connect segment a to dp of both 7-segment displays to:

a  → GP0  
b  → GP1  
c  → GP2  
d  → GP3  
e  → GP4  
f  → GP5  
g  → GP6  
dp → GP7

Common cathode pins of:

Left display → GP16
Right display → GP17

💻 Full MicroPython Code

from machine import Pin, PWM
import utime

# Segment pins a to dp (GPIO0 to GPIO7)
segment_pins = [0, 1, 2, 3, 4, 5, 6, 7]
segments = [Pin(pin, Pin.OUT) for pin in segment_pins]

# Digit control pins (common cathode control)
digit_pins = [Pin(16, Pin.OUT), Pin(17, Pin.OUT)]

# Buzzer using PWM (GPIO15)
buzzer = PWM(Pin(15))

# Buttons connected to GPIOs with internal pull-downs
btn_up = Pin(10, Pin.IN, Pin.PULL_DOWN)
btn_down = Pin(11, Pin.IN, Pin.PULL_DOWN)
btn_reset = Pin(12, Pin.IN, Pin.PULL_DOWN)
btn_stop = Pin(13, Pin.IN, Pin.PULL_DOWN)

# 7-segment digit patterns for 0-9 (common cathode)
digit_patterns = [
    (1,1,1,1,1,1,0,0),  # 0
    (0,1,1,0,0,0,0,0),  # 1
    (1,1,0,1,1,0,1,0),  # 2
    (1,1,1,1,0,0,1,0),  # 3
    (0,1,1,0,0,1,1,0),  # 4
    (1,0,1,1,0,1,1,0),  # 5
    (1,0,1,1,1,1,1,0),  # 6
    (1,1,1,0,0,0,0,0),  # 7
    (1,1,1,1,1,1,1,0),  # 8
    (1,1,1,1,0,1,1,0)   # 9
]

# Initialize counter and mode
counter = 0
mode = None  # 'up', 'down', or None (paused)
last_tick = utime.ticks_ms()

# -------- Buzzer Beep Functions -------- #
def beep_up():
    buzzer.freq(1000)
    buzzer.duty_u16(1000)
    utime.sleep(0.05)
    buzzer.duty_u16(0)

def beep_down():
    buzzer.freq(400)
    buzzer.duty_u16(1000)
    utime.sleep(0.1)
    buzzer.duty_u16(0)

# -------- Display Function -------- #
def display_digit(pos, digit):
    pattern = digit_patterns[digit]
    for seg, val in zip(segments, pattern):
        seg.value(val)

    # Activate only one digit at a time
    digit_pins[0].value(1)
    digit_pins[1].value(1)
    digit_pins[pos].value(0)
    utime.sleep_ms(5)
    digit_pins[pos].value(1)

# -------- Main Loop -------- #
while True:
    # ---- BUTTONS ---- #
    if btn_up.value():
        mode = "up"
        utime.sleep(0.3)

    if btn_down.value():
        mode = "down"
        utime.sleep(0.3)

    if btn_reset.value():
        counter = 0
        mode = None
        utime.sleep(0.3)

    if btn_stop.value():
        mode = None
        utime.sleep(0.3)

    # ---- COUNTING (every 1s) ---- #
    if mode and utime.ticks_diff(utime.ticks_ms(), last_tick) >= 1000:
        if mode == "up" and counter < 99:
            counter += 1
            beep_up()
        elif mode == "down" and counter > 0:
            counter -= 1
            beep_down()
        last_tick = utime.ticks_ms()

    # ---- SPLIT COUNTER INTO DIGITS ---- #
    tens = counter // 10
    ones = counter % 10

    # ---- DISPLAY BOTH DIGITS ---- #
    for _ in range(10):  # Repeat to reduce flickering
        display_digit(0, tens)
        display_digit(1, ones)

🔊 How the Sound Works

Action	Sound Type	Frequency
Count Up	Short beep	1000 Hz
Count Down	Lower tone	400 Hz
Reset/Stop	(You can add more if needed)

You can even add unique beep patterns if you like!

🧠 Why Use `_`?

Normally, in a loop like this:

for i in range(10):
    print(i)

The variable i holds values from 0 to 9.

But in your case, you’re not using that loop variable at all — you’re just repeating something 10 times.

So instead of writing:

for i in range(10):
    display_digit(0, tens)
    display_digit(1, ones)

…and having i sit there unused, we write:

for _ in range(10):
    display_digit(0, tens)
    display_digit(1, ones)

This tells readers (and Python) clearly:

“We’re just looping for repetition. We don’t need the counter.”

✅ Summary

Syntax	Meaning
`for i in range(10)`	Use `i` if you need the loop index
`for _ in range(10)`	Use `_` if you don’t care about the index

It’s a clean, readable, and recommended practice in Python when you don’t need the loop variable.

🔁 If `counter = 47`

We split it:

tens = 4
ones = 7

Now, this line runs:

for _ in range(10):
    display_digit(0, tens)   # Show 4 on first display
    display_digit(1, ones)   # Show 7 on second display

🧠 What Happens in `display_digit()`?

Let’s assume utime.sleep_ms(5) is used:

Loop iteration #1:

Display 1 ON: Show 4 for 5 milliseconds
Display 2 ON: Show 7 for 5 milliseconds

Loop iteration #2:

Repeat the same:
- 4 on digit 1 → 5ms
- 7 on digit 2 → 5ms

… and this is done 10 times total:

🧮 10 × (5ms + 5ms) = 100ms

So you’re refreshing the entire display 10 times in 100 milliseconds, which is fast enough that:

The human eye sees both digits as being constantly ON
No flicker is noticed
Both digits appear to light up simultaneously, even though only one is ON at a time

💡 Why This Works

Your eyes can’t notice flicker if the screen is refreshed faster than about 60 times per second (60Hz or ~16ms per frame).
This code is refreshing it much faster (~100Hz), so both digits look perfectly stable.

✅ Summary

Step	Duration
Show `4` on digit 1	5 ms
Show `7` on digit 2	5 ms
Repeat above steps 10×	Total ≈ 100 ms

🔁 And this cycle keeps running forever, so it looks like both digits are always glowing.

✅ Wiring Your Button with `Pin.PULL_DOWN`

Since your MicroPython code uses:

button_up = Pin(10, Pin.IN, Pin.PULL_DOWN)

That means:

The GPIO pin (GP10) will read 0 (LOW) when the button is not pressed.
When you press the button, you want it to connect to 3.3V, making it HIGH (1).

✅ So your button wiring should be:

Button Pin	Connects To
One side	3.3V (Pin 36 on Pico) ✅
Other side	GPIO10 (button input pin) ✅

📌 No external resistor is needed because you’re using the internal pull-down resistor.

🔁 What Happens:

Button not pressed:
GPIO10 is pulled LOW (0) by the internal pull-down.
Button pressed:
3.3V flows into GPIO10 → reads HIGH (1) → your code detects button press.

⚠️ Don’t do this:

❌ Don’t connect one side to GND and the other to GPIO10 when using Pin.PULL_DOWN, because that would never go HIGH.
❌ Don’t connect 3.3V directly to GPIO10 without a button — you must go through the button!

✅ Conclusion

Your setup:

One pin of button to 3.3V (Pin 36)
Other pin to GPIO10

✔️ Correct!

Main Program Loop

while True:

This loop keeps checking buttons and refreshing the display.

🧠 Code Explained in Simple Terms

🧱 1. Import necessary modules

pythonCopyEditfrom machine import Pin, PWM
import utime

machine: lets you control Pico’s hardware (GPIO, PWM, etc.).
Pin: controls GPIO pins.
PWM: controls the buzzer (to create tones).
utime: for delays, timers, etc.

💡 2. 7-Segment display setup

pythonCopyEditsegment_pins = [0, 1, 2, 3, 4, 5, 6, 7]
segments = [Pin(pin, Pin.OUT) for pin in segment_pins]

These GPIO pins are connected to segments a to dp of the 7-segment displays.
Each segment is set as an output pin.

pythonCopyEditdigit_pins = [Pin(16, Pin.OUT), Pin(17, Pin.OUT)]

These two pins control which digit to light up (common cathode).
One is for the tens digit, the other for the ones digit.

🔊 3. Buzzer setup

pythonCopyEditbuzzer = PWM(Pin(15))

Buzzer is connected to GPIO15 and controlled using PWM to make different sounds.

🎮 4. Button setup

pythonCopyEditbtn_up = Pin(10, Pin.IN, Pin.PULL_DOWN)
btn_down = Pin(11, Pin.IN, Pin.PULL_DOWN)
btn_reset = Pin(12, Pin.IN, Pin.PULL_DOWN)
btn_stop = Pin(13, Pin.IN, Pin.PULL_DOWN)

Four buttons:
- UP ➜ count up
- DOWN ➜ count down
- RESET ➜ set counter to 0 and stop
- STOP ➜ pause the counter
Each is connected with an internal pull-down resistor, so it reads 0 by default.

🔢 5. Digit patterns for displaying 0–9

pythonCopyEditdigit_patterns = [
    (1,1,1,1,1,1,0,0),  # 0
    (0,1,1,0,0,0,0,0),  # 1
    ...
    (1,1,1,1,0,1,1,0)   # 9
]

Each tuple controls the 8 segments (a to dp) of the display.
For example, 1 means ON (segment glows), 0 means OFF.

🔄 6. Counter setup

pythonCopyEditcounter = 0
mode = None
last_tick = utime.ticks_ms()

counter: stores the current number (0 to 99)
mode: "up", "down", or None (pause)
last_tick: stores the last time we counted 1 second

🎵 7. Beep sound functions

pythonCopyEditdef beep_up():
    buzzer.freq(1000)
    buzzer.duty_u16(1000)
    utime.sleep(0.05)
    buzzer.duty_u16(0)

Makes a high-pitch beep for UP counting.

pythonCopyEditdef beep_down():
    buzzer.freq(400)
    buzzer.duty_u16(1000)
    utime.sleep(0.1)
    buzzer.duty_u16(0)

Makes a lower-pitch beep for DOWN counting.

🔢 8. Display a single digit on a 7-segment

pythonCopyEditdef display_digit(pos, digit):
    pattern = digit_patterns[digit]
    for seg, val in zip(segments, pattern):
        seg.value(val)

    digit_pins[0].value(1)
    digit_pins[1].value(1)
    digit_pins[pos].value(0)
    utime.sleep_ms(5)
    digit_pins[pos].value(1)

pos: 0 = tens, 1 = ones.
Lights up segments for that digit using the pattern.
Activates the right display by pulling its pin LOW (common cathode).
Then waits 5 ms and turns it off again.
This is done repeatedly (many times per second) to create the illusion of both digits showing at once (called multiplexing).

🔁 9. Main loop

pythonCopyEditwhile True:

Runs forever.

🟢 Detect button presses

pythonCopyEditif btn_up.value():
    mode = "up"
    utime.sleep(0.3)

If UP button is pressed, set mode to "up", so counter starts increasing.

pythonCopyEditif btn_down.value():
    mode = "down"
    utime.sleep(0.3)

DOWN mode activated.

pythonCopyEditif btn_reset.value():
    counter = 0
    mode = None
    utime.sleep(0.3)

RESET ➜ counter goes back to 0 and stops.

pythonCopyEditif btn_stop.value():
    mode = None
    utime.sleep(0.3)

STOP ➜ pauses counting.

⏱ Update counter every 1 second

pythonCopyEditif mode and utime.ticks_diff(utime.ticks_ms(), last_tick) >= 1000:

Only update if a mode is active and 1 second has passed.

pythonCopyEditif mode == "up" and counter < 99:
    counter += 1
    beep_up()

Increase counter and beep, only up to 99

pythonCopyEditelif mode == "down" and counter > 0:
    counter -= 1
    beep_down()

Decrease counter and beep, only down to 0

pythonCopyEditlast_tick = utime.ticks_ms()

Reset the tick timer.

🔢 Split digits and display

pythonCopyEdittens = counter // 10
ones = counter % 10

for _ in range(10):
    display_digit(0, tens)
    display_digit(1, ones)

Break the counter into tens and ones digits.
Show each digit rapidly and repeatedly to make the display appear steady.

✅ Summary

This program turns your Raspberry Pi Pico into a 2-digit timer with:

Two 7-segment displays
Control using buttons (UP, DOWN, RESET, STOP)
Beep feedback for user interaction
Multiplexing for clean display

🧪 Try These Experiments

Add a buzzer beep when Reset is pressed.
Add auto stop at 99 or 0.
Use an OLED display instead of 7-segment.
Add LEDs for each button press.

Gilkut®️

🎯 What You’ll Learn

🧠 How It Works:

🧰 Components Needed

📌 Button Functions

🔌 Buzzer Connection

🔢 Segment to GPIO Pin Mapping

💻 Full MicroPython Code

🔊 How the Sound Works

🧠 Why Use _?

✅ Summary

🔁 If counter = 47

🧠 What Happens in display_digit()?

Loop iteration #1:

Loop iteration #2:

💡 Why This Works

✅ Summary

✅ Wiring Your Button with Pin.PULL_DOWN

✅ So your button wiring should be:

🔁 What Happens:

⚠️ Don’t do this:

✅ Conclusion

Main Program Loop

🧠 Code Explained in Simple Terms

🧱 1. Import necessary modules

💡 2. 7-Segment display setup

🔊 3. Buzzer setup

🎮 4. Button setup

🔢 5. Digit patterns for displaying 0–9

🔄 6. Counter setup

🎵 7. Beep sound functions

🔢 8. Display a single digit on a 7-segment

🔁 9. Main loop

🟢 Detect button presses

⏱ Update counter every 1 second

🔢 Split digits and display

✅ Summary

🧪 Try These Experiments

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🧠 Why Use `_`?

🔁 If `counter = 47`

🧠 What Happens in `display_digit()`?

✅ Wiring Your Button with `Pin.PULL_DOWN`