Project 10：8×8 Dot-matrix Display

1. Introduction

The dot-matrix display is an electronic digital display device that can show information on machines, clocks and many other devices. In this project, we will use the Raspberry Pi Pico to control the 8x8 LED dot matrix to make some patterns.

2. Components Required

Raspberry Pi Pico*1	Raspberry Pi Pico Expansion Board*1	Jumper Wires	Breadboard*1
8*8 Dot-matrix Display *1	220Ω Resistor*8	USB Cable*1

3. Component Knowledge

8*8 Dot-matrix display module:

The 8*8 dot matrix is composed of 64 LEDs, and each LED is placed at the intersection of a row and a column. When using a single-chip microcomputer to drive an 8*8 dot matrix, we need to use a total of 16 digital ports, which greatly wastes the data of the single-chip microcomputer. For this reason, we specially designed this module, using the HT16K33 chip to drive an 8*8 dot matrix, and only need to use the I2C communication port of the single-chip microcomputer to control the dot matrix, which greatly saves the microcontroller resources.

4. Circuit Diagram and Wiring Diagram

5. Test Code

The code used in this project is saved in the file KS3025 Keyestudio Raspberry Pi Pico Learning Kit Complete Edition\3. Raspberry Pi System\Python_Tutorial\2. Projects\Project 10：8×8 Dot-matrix Display.

You can move the code to anywhere. For example, we save it in the pi folder of the Raspberry Pi system, the route is home/pi/2. Projects.

Open“Thonny, click “This computer”→“home”→“pi”→“2. Projects”→“Project 10：8×8 Dot-matrix Display”and double-click“Project_10_8×8_Dot_Matrix_Display.py”

from machine import Pin
import time

#Define the pin of the row and Set to output
row1 = machine.Pin(18, machine.Pin.OUT)
row2 = machine.Pin(26, machine.Pin.OUT)
row3 = machine.Pin(17, machine.Pin.OUT)
row4 = machine.Pin(21, machine.Pin.OUT)
row5 = machine.Pin(10, machine.Pin.OUT)
row6 = machine.Pin(16, machine.Pin.OUT)
row7 = machine.Pin(11, machine.Pin.OUT)
row8 = machine.Pin(14, machine.Pin.OUT)
#Define the pins of the column and Set to output
col1 = machine.Pin(22, machine.Pin.OUT)
col2 = machine.Pin(12, machine.Pin.OUT)
col3 = machine.Pin(13, machine.Pin.OUT)
col4 = machine.Pin(19, machine.Pin.OUT)
col5 = machine.Pin(15, machine.Pin.OUT)
col6 = machine.Pin(20, machine.Pin.OUT)
col7 = machine.Pin(27, machine.Pin.OUT)
col8 = machine.Pin(28, machine.Pin.OUT)

#Sets the pin of the column to low level
col1.value(0)
col2.value(0)
col3.value(0)
col4.value(0)
col5.value(0)
col6.value(0)
col7.value(0)
col8.value(0)

#Since the column of the lattice has been set to low level, 
#the corresponding row of the lattice will light up when the pin of the row is at high level
def Row(d):
    if(d ==1):
        row1.value(1)  #Light the first line
    if(d ==2):
        row2.value(1)  #Light the second line
    if(d ==3):
        row3.value(1)
    if(d ==4):
        row4.value(1)
    if(d ==5):
        row5.value(1)
    if(d ==6):
        row6.value(1)
    if(d ==7):
        row7.value(1)
    if(d ==8):
        row8.value(1)
    
#Close the lattice
def off():
    row1.value(0)
    row2.value(0)
    row3.value(0)
    row4.value(0)
    row5.value(0)
    row6.value(0)
    row7.value(0)
    row8.value(0) 

try:
    print("test...")
    while True:
         for num in range(1,10):  #Light the lattice line by line
             Row(num)
             if(num == 9):  #Because the lattice has only 8 rows, and I'm limiting it here, is equal to 9
                off()      #Close the lattice
             time.sleep(0.2)

except:
    pass

6. Test Result

Ensure that the Raspberry Pi Pico is connected to the computer, click “Stop/Restart backend”.

Click “Run current script”, the code starts executing, we will see that the 8 x 8 dot matrix displays the character “A” 1S, “B” 1S, and “C” 1S. Then scroll to display the string “Hello World”repeatedly.  Click“Stop/Restart backend”to exit the program.