Example MCP3008

[curiosity4809]

Heres an example for MCP3008 on SPI

MCP3008.java

import com.pi4j.context.Context;
import com.pi4j.io.spi.Spi;
import com.pi4j.io.spi.SpiMode;
import com.pi4j.io.spi.SpiProvider;
import com.pi4j.io.gpio.digital.DigitalOutput;
import com.pi4j.io.gpio.digital.DigitalState;

/**
 * Base class for {@link SPIBus} devices.
 */
public class MCP3008 extends SPIBus {

	public static DigitalOutput chipSelectMCP3008;

	/** 
	 * Creates a {@link MCP3008}.
	 */
	public MCP3008(Spi bus) {
		super(bus);
	}

    /** 
	 * Creates a new {@link MCP3008} device.
	 *
	 * @param pi4j    {@link Context}
	 * @param cs	Number of Pin for ChipSelect
     * @return The new device.
	 */
	public static MCP3008 create(Context pi4j, int cs) {
		createCS(pi4j,cs);
		SpiProvider spiProvider = pi4j.provider("pigpio-spi");
		var config  = Spi.newConfigBuilder(pi4j)
	            .id("mcp3008")
	            .name("MCP3008 ADC-Module")
                    .address(0)
                    .mode(SpiMode.MODE_1)
                    .baud(500000)
                    .build();       
	    return new MCP3008(spiProvider.create(config));
	}

	/** 
	 * Creates a new {@link MCP3008} device.
	 *
	 * @param pi4j    {@link Context}
	 * @param cs	Number of Pin for ChipSelect
	 */
	public static void createCS(Context pi4j, int cs) {
        var lgpio8Config = DigitalOutput.newConfigBuilder(pi4j)
            .id("gpio8")
            .name("Output for Chipselect MCP3008")
            .address(cs)
            .shutdown(DigitalState.HIGH)
            .initial(DigitalState.HIGH)
            .provider("pigpio-digital-output");
        chipSelectMCP3008 = pi4j.create(lgpio8Config);
	}

	/** 
	 * reads the ADC-Value (0..1023 | 1024 digits);
	 * 
	 * @param channel ADC-Channel we read from
	 * @return Integer with ADC-Value.
	 */
    public int readADC(byte channel){
	chipSelectMCP3008.low();
        transferMessageMCP3008(channel);
	chipSelectMCP3008.high();
        return messageToUnsignedIntMCP3008();
    }
}

SPIBus.java

import com.pi4j.io.spi.Spi;

/**
 * Base class for {@link SPIBus} devices.
 */
public class SPIBus {


    private final Spi _bus;
    private final byte[] _wrBufSpi = new byte[3];
    private final byte[] _rdBufSpi = new byte[3];

	/** 
	 * Creates a {@link SPIDevice}.
	 *
	 * @param bus The {@link Spi} bus to communicate with.
	 */
	public SPIBus(Spi bus) {
		_bus = bus;
	}


    public final void transferMessageMCP3008(byte channel) {
        _wrBufSpi[0] = (byte) 0b00000001;
        _wrBufSpi[1] = channel;
        _wrBufSpi[2] = 0x00;
        _bus.transfer(_wrBufSpi,_rdBufSpi,3);
	}

    public int messageToUnsignedIntMCP3008 () {
        int unsignedInt;

        unsignedInt = ((_rdBufSpi[1] & 0xff) << 8) | (_rdBufSpi[2] & 0xff);
        return unsignedInt;

    }
    
}```