Raspberry Pi Pico - 74HC595 4-Digit 7-Segment Display
The Raspberry Pi Pico is a low-cost, high-performance microcontroller board built on the RP2040 chip. Paired with MicroPython and the DIYables 4-Digit 7-Segment Display module (74HC595), you can easily show numbers, text, and sensor readings on a bright LED display.
This tutorial walks you through:
- Connecting the 74HC595-based 4-digit 7-segment display to a Raspberry Pi Pico — only 3 data pins needed.
- Displaying integers, floats, and text strings.
- Showing temperature with the degree symbol (°C / °F).
- Displaying time with a blinking dot separator.
- Blinking the display on and off.
- Using the auto-refresh feature — no manual refresh loop required.
Components Needed
Or you can buy the following kits:
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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Additionally, some of these links are for products from our own brand, DIYables .
Additionally, some of these links are for products from our own brand, DIYables .
The 4-Digit 7-Segment Display 74HC595 Module
The DIYables 4-Digit 7-Segment Display 74HC595 module is a compact LED display driven by two 74HC595 shift registers. It shows 4 digits and 4 decimal point dots. Because the shift registers handle all the segment and digit driving, the Raspberry Pi Pico only needs 3 GPIO pins (clock, latch, and data) instead of the 12+ pins a raw display would require.
The Pico communicates with the module by shifting out segment data and digit-select data serially. The library handles this automatically using a hardware Timer for multiplexing — each digit is refreshed in turn at high speed, so all 4 digits appear lit simultaneously.
Key features of the module:
- Only 3 wires for data (SCLK, RCLK, DIO) plus power.
- 4 decimal point dots — individually controllable.
- Common anode or common cathode variants available.
- 5V or 3.3V compatible.
Pin Description
| Pin | Purpose | Raspberry Pi Pico Connection |
|---|---|---|
| SCLK (SH_CP) | Serial clock input | Connect to GP2 |
| RCLK (ST_CP) | Register clock / latch | Connect to GP1 |
| DIO (DS) | Serial data input | Connect to GP0 |
| VCC | 3.3V to 5V power input | Connect to 3V3(OUT) |
| GND | Ground | Connect to GND |
Wiring
The Raspberry Pi Pico operates at 3.3V logic natively. The 74HC595 module works with both 3.3V and 5V, so you wire directly — no level shifting needed.
| 74HC595 Module | Raspberry Pi Pico | Notes |
|---|---|---|
| SCLK (SH_CP) | GP2 | Serial clock |
| RCLK (ST_CP) | GP1 | Latch / register clock |
| DIO (DS) | GP0 | Serial data |
| VCC | 3V3(OUT) | Power (3.3V output pin) |
| GND | GND | Ground |
This image is created using Fritzing. Click to enlarge image
Tip: You can use any available GPIO pins on the Pico. Just update the pin numbers in the code.
Detailed Instructions
Here's instructions on how to set up and run your MicroPython code on the Raspberry Pi Pico using Thonny IDE:
- Make sure Thonny IDE is installed on your computer.
- Confirm that MicroPython firmware is loaded on your Raspberry Pi Pico board.
- If this is your first time using a Raspberry Pi Pico with MicroPython, check out the Raspberry Pi Pico MicroPython Getting Started guide for step-by-step instructions.
- Connect the Raspberry Pi Pico board to the 4-digit 7-segment display module according to the provided diagram.
- Connect the Raspberry Pi Pico board to your computer with a USB cable.
- Open Thonny IDE on your computer.
- In Thonny IDE, go to Tools Options.
- Under the Interpreter tab, choose MicroPython (Raspberry Pi Pico) from the dropdown menu.
- Make sure the correct port is selected. Thonny IDE usually detects it automatically, but you might need to select it manually (like COM12 on Windows or /dev/ttyACM0 on Linux).
- Navigate to the Tools Manage packages on the Thonny IDE.
- Search "DIYables-MicroPython-4Digit7Segment-74HC595", then find the 4-Digit 7-Segment Display library created by DIYables.
- Click on DIYables-MicroPython-4Digit7Segment-74HC595, then click Install button to install the library.
- Copy the provided MicroPython code and paste it into Thonny's editor.
- Save the code to your Raspberry Pi Pico by:
- Clicking the Save button or pressing Ctrl+S.
- In the save dialog, choose MicroPython device.
- Name the file main.py.
- Click the green Run button (or press F5) to execute the script.
- Observe the display — you should see numbers, text, or other content appear on the 7-segment display.
Starter Code Template
from DIYables_MicroPython_4Digit7Segment_74HC595 import Display4Digit7Segment74HC595
import time
display = Display4Digit7Segment74HC595(sclk_pin=2, rclk_pin=1, dio_pin=0, common_anode=True)
#The display auto-refreshes in the background using a hardware Timer.
#Just call display.print() and the display stays on automatically.
display.print(1234)
Raspberry Pi Pico Code — Display Integers
"""
Example: Display integer numbers on 4-digit 7-segment display with 74HC595.
Works with: ESP32, Raspberry Pi Pico, Arduino Nano ESP32, Arduino Nano R1 WiFi
Wiring guide:
Raspberry Pi Pico:
74HC595 Module Raspberry Pi Pico
────────────── ─────────────────
SCLK (SH_CP) -> GP2
RCLK (ST_CP) -> GP1
DIO (DS) -> GP0
VCC -> 3.3V (pin 36)
GND -> GND (pin 38)
"""
from DIYables_MicroPython_4Digit7Segment_74HC595 import Display4Digit7Segment74HC595
import time
SCLK_PIN = 2
RCLK_PIN = 1
DIO_PIN = 0
display = Display4Digit7Segment74HC595(SCLK_PIN, RCLK_PIN, DIO_PIN, common_anode=True)
while True:
# Display integers
numbers = [0, 42, 1234, -5, -123, 9999]
for num in numbers:
display.print(num)
time.sleep(2)
# Display with zero padding
display.print(42, zero_pad=True) # Shows "0042"
time.sleep(2)
Try It
- Wire the module, connect the Pico via USB.
- Upload the code using Thonny IDE.
- The display cycles through several integers (0, 42, 1234, -5, -123, 9999) and a zero-padded number (0042).
Integer Display
The print() method auto-detects integers and formats them right-aligned on the display.
| Method Call | Display Shows | Notes |
|---|---|---|
| display.print(0) | " 0" | Single digit, right-aligned |
| display.print(42) | " 42" | Two digits |
| display.print(1234) | "1234" | All four digits |
| display.print(-5) | " -5" | Negative with minus sign |
| display.print(-123) | "-123" | Negative, full width |
| display.print(9999) | "9999" | Maximum positive value |
| display.print(42, zero_pad=True) | "0042" | Leading zeros |
Integer range: -999 to 9999. Values outside this range display "Err".
Raspberry Pi Pico Code — Display Floats
"""
Example: Display float numbers on 4-digit 7-segment display with 74HC595.
Works with: ESP32, Raspberry Pi Pico, Arduino Nano ESP32, Arduino Nano R1 WiFi
Wiring guide:
Raspberry Pi Pico:
74HC595 Module Raspberry Pi Pico
────────────── ─────────────────
SCLK (SH_CP) -> GP2
RCLK (ST_CP) -> GP1
DIO (DS) -> GP0
VCC -> 3.3V (pin 36)
GND -> GND (pin 38)
"""
from DIYables_MicroPython_4Digit7Segment_74HC595 import Display4Digit7Segment74HC595
import time
SCLK_PIN = 2
RCLK_PIN = 1
DIO_PIN = 0
display = Display4Digit7Segment74HC595(SCLK_PIN, RCLK_PIN, DIO_PIN, common_anode=True)
while True:
# Display floats with auto decimal places
floats = [1.5, 12.34, 3.141, -1.2, 0.5]
for num in floats:
display.print(num)
time.sleep(2)
# Display with specific decimal places
display.print(23.5, decimal_places=1) # Shows "23.5"
time.sleep(2)
# Display 1.5 with auto decimal places
display.print(1.5) # Shows "1.5"
time.sleep(2)
# Display 1.5 with 2 decimal places
display.print(1.5, decimal_places=2) # Shows "1.50"
time.sleep(2)
# Display 1.5 with 2 decimal places and zero padding
display.print(1.5, decimal_places=2, zero_pad=True) # Shows "01.50"
time.sleep(2)
Float Display
The decimal point dot is automatically placed at the correct position. You can let the library choose the number of decimal places, or specify it manually.
| Method Call | Display Shows | Notes |
|---|---|---|
| display.print(1.5) | " 1.5" | Auto decimal places |
| display.print(12.34) | "12.34" | Auto — 2 decimal places |
| display.print(3.141) | "3.141" | Auto — 3 decimal places |
| display.print(23.5, decimal_places=1) | "23.5" | Forced 1 decimal place |
| display.print(1.5, decimal_places=2) | " 1.50" | Forced 2 decimal places with trailing zero |
| display.print(1.5, decimal_places=2, zero_pad=True) | "01.50" | Zero-padded with 2 decimal places |
Raspberry Pi Pico Code — Display Text, Degree, and Temperature
"""
Example: Display text, special characters, and temperature on 4-digit 7-segment display.
Works with: ESP32, Raspberry Pi Pico, Arduino Nano ESP32, Arduino Nano R1 WiFi
Wiring guide:
Raspberry Pi Pico:
74HC595 Module Raspberry Pi Pico
────────────── ─────────────────
SCLK (SH_CP) -> GP2
RCLK (ST_CP) -> GP1
DIO (DS) -> GP0
VCC -> 3.3V (pin 36)
GND -> GND (pin 38)
"""
from DIYables_MicroPython_4Digit7Segment_74HC595 import Display4Digit7Segment74HC595
import time
SCLK_PIN = 2
RCLK_PIN = 1
DIO_PIN = 0
display = Display4Digit7Segment74HC595(SCLK_PIN, RCLK_PIN, DIO_PIN, common_anode=True)
while True:
# Display text strings
texts = ["HELP", "Hi", "COOL", "done"]
for text in texts:
display.print(text)
time.sleep(2)
# Display temperature with degree symbol
display.print_temperature(25, 'C') # Shows "25°C"
time.sleep(2)
display.print_temperature(72, 'F') # Shows "72°F"
time.sleep(2)
# Display string with degree constant
display.print("25" + display.DEGREE + "C") # Same as print_temperature(25, 'C')
time.sleep(2)
# Display string with dots
display.print("1.2.3.4") # Shows "1.2.3.4" with dots on digits 0,1,2
time.sleep(2)
Supported Characters
The display can show a subset of alphabetic characters that are legible on a 7-segment display:
- Digits: 0-9
- Letters: A, b, C, c, d, E, F, G, H, h, I, i, J, L, n, O, o, P, r, S, t, U, u, Y
- Special: ° (degree), - (dash), _ (underscore), (space)
Temperature Display
| Method Call | Display Shows | Notes |
|---|---|---|
| display.print_temperature(25, 'C') | "25°C" | Celsius |
| display.print_temperature(72, 'F') | "72°F" | Fahrenheit |
| display.print_temperature(-5, 'C') | "-5°C" | Negative temperature |
| display.print_temperature(100, 'C') | "100°" | No room for unit |
You can also build temperature strings manually using the DEGREE constant:
display.print("25" + display.DEGREE + "C") # Same as print_temperature(25, 'C')
Dot Handling in Strings
A . character in a string activates the decimal point dot on the preceding digit rather than occupying its own position:
display.print("1.2.3.4") # Shows digits 1, 2, 3, 4 with dots on digits 0, 1, 2
Raspberry Pi Pico Code — Display Time
"""
Example: Display time with blinking dot separator on 4-digit 7-segment display.
Note: This module has dots only (no colon). The dot on digit 1 is used as a time separator.
Works with: ESP32, Raspberry Pi Pico, Arduino Nano ESP32, Arduino Nano R1 WiFi
Wiring guide:
Raspberry Pi Pico:
74HC595 Module Raspberry Pi Pico
────────────── ─────────────────
SCLK (SH_CP) -> GP2
RCLK (ST_CP) -> GP1
DIO (DS) -> GP0
VCC -> 3.3V (pin 36)
GND -> GND (pin 38)
"""
from DIYables_MicroPython_4Digit7Segment_74HC595 import Display4Digit7Segment74HC595
import time
SCLK_PIN = 2
RCLK_PIN = 1
DIO_PIN = 0
display = Display4Digit7Segment74HC595(SCLK_PIN, RCLK_PIN, DIO_PIN, common_anode=True)
hours = 12
minutes = 30
colon_on = True
while True:
display.print_time(hours, minutes, colon=colon_on)
time.sleep(0.5) # Toggle dot separator every 500ms for blinking effect
colon_on = not colon_on
Time Display
This module has dots only (no colon). The print_time() method uses the dot on digit 1 (second from left) as a time separator.
| Method Call | Display Shows | Notes |
|---|---|---|
| display.print_time(12, 30) | "12.30" | Dot separator on |
| display.print_time(9, 5) | "09.05" | Auto zero-padding |
| display.print_time(12, 30, colon=False) | "12 30" | Dot separator off |
Blinking effect: Toggle the colon parameter every 500ms in your main loop to create a blinking time separator.
Raspberry Pi Pico Code — Blink Display
"""
Example: Blink integer, float, and text on 4-digit 7-segment display.
Uses off() to stop the display and on() to restart it.
Works with: ESP32, Raspberry Pi Pico, Arduino Nano ESP32, Arduino Nano R1 WiFi
Wiring guide:
Raspberry Pi Pico:
74HC595 Module Raspberry Pi Pico
────────────── ─────────────────
SCLK (SH_CP) -> GP2
RCLK (ST_CP) -> GP1
DIO (DS) -> GP0
VCC -> 3.3V (pin 36)
GND -> GND (pin 38)
"""
from DIYables_MicroPython_4Digit7Segment_74HC595 import Display4Digit7Segment74HC595
import time
SCLK_PIN = 2
RCLK_PIN = 1
DIO_PIN = 0
display = Display4Digit7Segment74HC595(SCLK_PIN, RCLK_PIN, DIO_PIN, common_anode=True)
while True:
# Blink an integer
display.print(1234)
for _ in range(5): # Blink 5 times
display.off()
time.sleep(0.3)
display.on()
time.sleep(0.3)
time.sleep(1)
# Blink a float
display.print(12.34)
for _ in range(5): # Blink 5 times
display.off()
time.sleep(0.3)
display.on()
time.sleep(0.3)
time.sleep(1)
# Blink text
display.print("HELP")
for _ in range(5): # Blink 5 times
display.off()
time.sleep(0.3)
display.on()
time.sleep(0.3)
time.sleep(1)
Display On/Off Control
The off() method stops the auto-refresh timer and turns off all segments. The on() method restarts the timer — the display resumes showing whatever was last printed.
| Method | Action | Notes |
|---|---|---|
| display.off() | Stop display and blank all segments | Timer is stopped |
| display.on() | Restart display with current content | Timer resumes |
| display.clear() | Clear the display buffer | Display shows blank |
Use off() and on() in a loop to create a blinking effect. The display content (set by print()) is preserved during off().
API Summary
For the full API reference with detailed parameters and examples, see the Library Reference.
| Method | Description |
|---|---|
| print(value, decimal_places, zero_pad) | Display int, float, or string (auto-detects type) |
| print_temperature(temperature, unit) | Display temperature with ° symbol |
| print_time(hours, minutes, colon) | Display time HH.MM with dot separator |
| clear() | Clear the display buffer |
| off() | Stop auto-refresh and blank the display |
| on() | Restart auto-refresh |
| set_char(position, char) | Set character at position (0-3) |
| set_number(position, number) | Set digit 0-9 at position (0-3) |
| set_dot(position, state) | Set decimal point at position (0-3) |
| set_segments(position, segments) | Set raw segment bits at position (0-3) |
Next Steps
- Explore the Library Reference for the full API including low-level segment control.
- Combine the display with sensors (e.g., DHT11, DS18B20) to build a temperature monitor.
- Use print_time() with the Pico's RTC or NTP to build a simple clock.
- Add buttons to create a countdown timer or stopwatch.