Spi Matrix with Pi4j V2.0

[matti318]

Hello, I would like to operate a matrix 8x8 on my Raspberry with Pi4j V2.0, unfortunately there are instructions only with crowpi. But I have Raspbian on the Raspberry. Is there a tutorial on how to do it easily with Raspbian and the Matrix?
greeting

[FDelporte]

CrowPi OS is actually the same as Raspbian (now known as Raspberry Pi OS) with some additional settings. So you should be able to run the exact same code on both OS versions.

One thing to take into account: if using SPI, you may need to set your Pi4J context yourself instead to make sure the right libraries are used to communicate with SPI over PiGpio as is done on https://github.com/Pi4J/pi4j-example-crowpi/blob/62977aa4564bef6edd4fc50fa6c5feeafaadc0b0/src/main/java/com/pi4j/crowpi/helpers/CrowPiPlatform.java#L29

[matti318]

Here is my code. It should be a simple code to test. It worked fine with version 1.4.
`
import com.pi4j.Pi4J;
import com.pi4j.io.spi.Spi;
import com.pi4j.io.spi.SpiConfig;
import java.io.IOException;
import com.pi4j.context.Context;

public class Matrix {

public static void main(String[] args) throws InterruptedException, IOException{
    var pi4j = Pi4J.newAutoContext();
    Max7219 neu = new Max7219(pi4j.create(buildSpiConfig(pi4j, 0, 8000000)));
    System.out.println("hello");

    neu.initial();
    neu.aus();
    
    neu.execute((byte)0, (byte)129);

// neu.execute((byte)0x0c, (byte)0x00);

}
private static SpiConfig buildSpiConfig(Context pi4j, int channel, int baud) {
    return Spi.newConfigBuilder(pi4j)
        .id("SPI" + channel)
        .name("LED Matrix")
        .address(channel)

// .baud(baud)
.build();}
}

class Max7219{
protected final Spi spi;
public Max7219(Spi spi) {
this.spi = spi;}

 void initial() throws IOException, InterruptedException{ // hier wird alles initialisiert
    execute((byte) 0x09, (byte) 0x00); // decode mode
    execute((byte)0x0a, (byte)15); // intensität 1-15
    execute((byte)0x0b, (byte)0x07); // scan limit, 07 ist stehet fuer 8 Reihen
    execute((byte)0x0c, (byte)0x01); // steht fuer shutdown, 01 ist normal mod
    execute((byte)0x0f, (byte)0x00); //display test, 00 ist aus
}


 void aus()  throws IOException, InterruptedException{  //schaltet erst einmal alles aus
    int end = 8;
    for (int i = 1; i <=end; i++) {
        spi.write((byte)i, (byte)0);
    System.out.println(i);}
    }
 public void execute(byte command, byte data) {
        spi.write(command, data);

}
}
`

What else do you have to change?

[FDelporte]

can you replace the newAutoContext() with PiGpio provider as in https://github.com/Pi4J/pi4j-example-crowpi/blob/62977aa4564bef6edd4fc50fa6c5feeafaadc0b0/src/main/java/com/pi4j/crowpi/helpers/CrowPiPlatform.java#L29?

Pi4J.newContextBuilder()
            .noAutoDetect()
            .add(
                PiGpioDigitalInputProvider.newInstance(piGpio),
                PiGpioDigitalOutputProvider.newInstance(piGpio),
                PiGpioPwmProvider.newInstance(piGpio),
                PiGpioI2CProvider.newInstance(piGpio),
                PiGpioSerialProvider.newInstance(piGpio),
                PiGpioSpiProvider.newInstance(piGpio)
            )
            .build();

[matti318]

How do you mean that exactly? I have to pass parameters for the Max7219 class for the constructor.

private static SpiConfig buildSpiConfig(Context pi4j, int channel, int baud) {
final var piGpio = PiGpio.newNativeInstance();
return Pi4J.newContextBuilder()
.noAutoDetect()
.add(new Matrix())
.add(
PiGpioDigitalInputProvider.newInstance(piGpio),
PiGpioDigitalOutputProvider.newInstance(piGpio),
PiGpioPwmProvider.newInstance(piGpio),
PiGpioI2CProvider.newInstance(piGpio),
PiGpioSerialProvider.newInstance(piGpio),
PiGpioSpiProvider.newInstance(piGpio)
)
.build();
}

Does not work like that.

[matti318]

Now the code works. Is the code okay like that?

import com.pi4j.Pi4J;
import com.pi4j.io.spi.Spi;
import com.pi4j.io.spi.SpiConfig;
import java.io.IOException;
import com.pi4j.context.Context;
import com.pi4j.library.pigpio.PiGpio;
import com.pi4j.plugin.pigpio.provider.gpio.digital.PiGpioDigitalInputProvider;
import com.pi4j.plugin.pigpio.provider.gpio.digital.PiGpioDigitalOutputProvider;
import com.pi4j.plugin.pigpio.provider.i2c.PiGpioI2CProvider;
import com.pi4j.plugin.pigpio.provider.pwm.PiGpioPwmProvider;
import com.pi4j.plugin.pigpio.provider.serial.PiGpioSerialProvider;
import com.pi4j.plugin.pigpio.provider.spi.PiGpioSpiProvider;


public class Matrix {


	public static void main(String[] args) throws InterruptedException, IOException{
		final var piGpio = PiGpio.newNativeInstance();
		var pi4j = Pi4J.newContextBuilder()
	            .noAutoDetect()
	            .add(
	                PiGpioDigitalInputProvider.newInstance(piGpio),
	                PiGpioDigitalOutputProvider.newInstance(piGpio),
	                PiGpioPwmProvider.newInstance(piGpio),
	                PiGpioI2CProvider.newInstance(piGpio),
	                PiGpioSerialProvider.newInstance(piGpio),
	                PiGpioSpiProvider.newInstance(piGpio)
	            )
	            .build();
		
		Max7219 neu = new Max7219(pi4j.create(buildSpiConfig(pi4j, 0, 8000000)));//(buildSpiConfig(pi4j, 0, 8000000)));
		System.out.println("hhello");
		neu.initial();
		neu.aus();
		neu.execute((byte)1, (byte)129);	
	}
	
	private static SpiConfig  buildSpiConfig(Context pi4j, int channel, int baud) {
           return Spi.newConfigBuilder(pi4j)
              .id("SPI" + channel)
              .name("Matrix")
              .address(channel)
              .baud(baud)
              .build();
       }
}

class Max7219{
	protected final Spi spi;
	public Max7219(Spi spi) {
		this.spi = spi;
        }
	
	void initial() throws IOException, InterruptedException{ // hier wird alles initialisiert
		execute((byte) 0x09, (byte) 0x00); // decode mode
		execute((byte)0x0a, (byte)1); // intensität 1-15
		execute((byte)0x0b, (byte)0x07); // scan limit, 07 ist stehet fuer 8 Reihen
		execute((byte)0x0c, (byte)0x01); // steht fuer shutdown, 01 ist normal mod
		execute((byte)0x0f, (byte)0x00); //display test, 00 ist aus
	}
	
	void aus()  throws IOException, InterruptedException{  //schaltet erst einmal alles aus
		int end = 8;
		for (int i = 1; i <=end; i++) {
			execute((byte)i, (byte)0);
			System.out.println("nuna" + i);
                }
        }

	 public void execute(byte command, byte data){
	     spi.write(command, data);      
        }
}

[FDelporte]

Hey, indeed looks OK, without running your code myself ;-)
Can you maybe try to only include the SpiProvider, as I guess that's the only type you are using?

var pi4j = Pi4J.newContextBuilder()
            .noAutoDetect()
            .add(
                PiGpioSpiProvider.newInstance(piGpio)
            )
            .build();

[matti318]

OK, that works. Thanks very much.

[matti318]

OK, that works. Thanks very much.

[FDelporte]

Thanks for your feedback!
I added this to the documentation page on https://pi4j.com/documentation/io-examples/spi/

[matti318]

thanks