I2CInterface.java

package robotCore;
 
import java.io.IOException;
 
import com.pi4j.context.Context;
import com.pi4j.io.i2c.I2C;
import com.pi4j.io.i2c.I2CConfig;

public class I2CInterface {
    private static final int BUS = 1;
 
    private final I2C m_device;
 
    I2CInterface(int addr) {
        Context pi4j = Pi4JContext.get();
        String id = String.format("i2c-%d-0x%02x", BUS, addr);
 
        I2C device = null;
        try {
            // Pi4J requires unique IDs, so reuse the device if it was already created.
            if (pi4j.registry().exists(id)) {
                device = pi4j.registry().get(id, I2C.class);
            } else {
                I2CConfig config = I2C.newConfigBuilder(pi4j)
                        .id(id)
                        .bus(BUS)
                        .device(addr)
                        .build();
                device = pi4j.create(config);
            }
        } catch (RuntimeException e) {
            e.printStackTrace();
        }
        m_device = device;
    }

    public int read(byte[] buffer, int offset, int length) throws IOException {
        checkDevice();
        try {
            int count = m_device.read(buffer, offset, length);
            if (count < 0) {
                throw new IOException("I2C read failed: " + count);
            }
            return count;
        } catch (RuntimeException e) {
            throw new IOException("I2C read failed", e);
        }
    }

    public void write(byte[] data) throws IOException {
        checkDevice();
        try {
            int count = m_device.write(data);
            if (count < 0) {
                throw new IOException("I2C write failed: " + count);
            }
        } catch (RuntimeException e) {
            throw new IOException("I2C write failed", e);
        }
    }

    public int writeRead(byte[] writeData, byte[] buffer, int offset, int length) throws IOException {
        checkDevice();
        try {
            int count = m_device.readRegister(writeData, buffer, offset, length);
            if (count < 0) {
                throw new IOException("I2C write/read failed: " + count);
            }
            return count;
        } catch (RuntimeException e) {
            throw new IOException("I2C write/read failed", e);
        }
    }
 
    private void checkDevice() throws IOException {
        if (m_device == null) {
            throw new IOException("I2C device was not opened; see the earlier stack trace");
        }
    }
}