View source for Experiment 29: MAX7219 LED Matrix Experiment

*[[Basic Experiment Kits For Arduino]]
*[[Basic Experiment Kits For Raspberry Pi]]
== Arduino ==
=== Experimental Phenomenon ===
* The module cyclically displays patterns when powered on.

=== Precautions ===
* When wiring, pay attention to the direction. The left side pin header is the input terminal (1088AS silkscreen is on the top of the PCB board).
* Be mindful of the LED orientation. If the display is abnormal, please reverse the insertion direction.

=== Circuit Connection ===
*[[File:实验二十九：MAX7219点阵实验_接线.png|800px]]


=== Reference Program ===
<pre>
#include "LedControl.h"
int DIN = 4;
int CS =  3;
int CLK = 2;

LedControl lc=LedControl(DIN,CLK,CS,0);

void setup(){
 lc.shutdown(0,false);       
 lc.setIntensity(0,15);      //Adjust the brightness maximum is 15
 lc.clearDisplay(0);    
}

void loop(){ 
    
    //Facial Expression
    byte smile[8]=   {0x3C,0x42,0xA5,0x81,0xA5,0x99,0x42,0x3C};
    byte neutral[8]= {0x3C,0x42,0xA5,0x81,0xBD,0x81,0x42,0x3C};
    byte sad[8]=   {0x3C,0x42,0xA5,0x81,0x99,0xA5,0x42,0x3C};
   
    //Arrow
    byte arrow_up[8]= {0x18,0x3C,0x7E,0xFF,0x18,0x18,0x18,0x18};
    byte arrow_down[8]= {0x18,0x18,0x18,0x18,0xFF,0x7E,0x3C,0x18};
   
    
    //Alternate Pattern
    byte d1[8]= {0xAA,0x55,0xAA,0x55,0xAA,0x55,0xAA,0x55};
    byte d2[8]= {0x55,0xAA,0x55,0xAA,0x55,0xAA,0x55,0xAA};
    
    //Moving car
    byte b1[8]= {0x00,0x00,0x00,0x00,0x18,0x3C,0x18,0x3C};//8x8 LED dot matrix pattern generated by software
    byte b2[8]= {0x00,0x00,0x00,0x18,0x3C,0x18,0x3C,0x00};
    byte b3[8]= {0x00,0x00,0x18,0x3C,0x18,0x3C,0x00,0x00};
    byte b4[8]= {0x00,0x18,0x3C,0x18,0x3C,0x00,0x00,0x00};
    byte b5[8]= {0x18,0x3C,0x18,0x3C,0x00,0x00,0x00,0x00};
    byte b6[8]= {0x3C,0x18,0x3C,0x00,0x00,0x00,0x00,0x18};
    byte b7[8]= {0x18,0x3C,0x00,0x00,0x00,0x00,0x18,0x3C};
    byte b8[8]= {0x3C,0x00,0x00,0x00,0x00,0x18,0x3C,0x18};


//Moving car
    printByte(b1);
    delay(50);
    printByte(b2);
    delay(50);
    printByte(b3);
    delay(50);
    printByte(b4);
    delay(50);
    printByte(b5);
    delay(50);
    printByte(b6);
    delay(50);
    printByte(b7);
    delay(50);
    printByte(b8);
    delay(50);

//alternate pattern
    printByte(d1);
    delay(100);

    printByte(d2);
    delay(100);

//Arrow
    printByte(arrow_up);
    delay(2000);

    printByte(arrow_down);
    delay(2000);

   
//Facial Expression   
    printByte(smile);
     
    delay(1000);

    printByte(neutral);
    
    delay(1000);

    printByte(sad);    

    delay(1000);
   
 
}

void printByte(byte character [])
{
  int i = 0;
  for(i=0;i<8;i++)
  {
    lc.setRow(0,i,character[i]);
  }
}
</pre>

== Raspberry Pi ==
=== Circuit Connection ===
*[[File:实验二十九：MAX7219点阵实验_接线1.png|800px]]

=== Program Execution ===
==== Python ====
* Install the gpiozero library
**You can use the following command to install the library:
<pre>
sudo apt update
sudo apt install python3-gpiozero
</pre>
:*For other systems on the Raspberry Pi, you can use the following command to install the library:
<pre>
sudo pip3 install gpiozero
</pre>
:*Run the following command to view the GPIO pin definitions on the Raspberry Pi:
<pre>
pinout
</pre>
*Download the Raspberry Pi reference example, unzip the file, copy it to the user directory, and run it:
<pre>
cd raspberrypi/29/python_gpiozero
python MAX7219.py
</pre>
*At this point, you can see the Raspberry Pi running the program correctly. To exit, press ctrl+C.
*Command explanation: '''gpiozero.OutputDevice(pin, active_high, initial_value)'''
** Main parameters:
*** pin: GPIO pin number
*** active_high: Internal pull-up/pull-down resistor setting
**** When set to True (default), on() sets the pin to High, and off() sets the pin to LOW.
**** When set to False, on() sets the pin to LOW, and off() sets the pin to High.
*** initial_value:
**** If False (default), all LEDs are initially off.
**** If None, the initial state of all LEDs is unstable.
**** If True, all LEDs are initially on.

*For more commands, please refer to the [https://gpiozero.readthedocs.io/en/latest/installing.html gpiozero documentation]

== Example Download ==
* [[:File:Basic Experiment Kits For Arduino.zip|Arduino Example Programs]]
* [[:File:Basic Experiment Kits For Raspberry Pi.zip|Raspberry Pi 5 Example Programs in Python]]

== Related Examples ==
{{Arduino and Raspberry Pi Case}}