processing/java/libraries/io/src/processing/io/SPI.java at master · johan718/processing · GitHub

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/* -*- mode: java; c-basic-offset: 2; indent-tabs-mode: nil -*- */

Hardware I/O library developed by Gottfried Haider as part of GSoC 2015

This library is free software; you can redistribute it and/or

modify it under the terms of the GNU Lesser General Public

License as published by the Free Software Foundation; either

version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General

Public License along with this library; if not, write to the

Free Software Foundation, Inc., 59 Temple Place, Suite 330,

Boston, MA 02111-1307 USA

package processing.io;

import processing.io.NativeInterface;

import java.io.File;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.HashMap;

import java.util.Map;

/**

* @webref

public class SPI {

/**

* CPOL=0, CPHA=0, most common

public static final int MODE0 = 0;

/**

* CPOL=0, CPHA=1

public static final int MODE1 = 1;

/**

* CPOL=1, CPHA=0

public static final int MODE2 = 2;

/**

* CPOL=1, CPHA=1

public static final int MODE3 = 3;

/**

* most significant bit first, most common

public static final int MSBFIRST = 0;

/**

* least significant bit first

public static final int LSBFIRST = 1;

protected int dataOrder = 0;

protected String dev;

protected int handle;

protected int maxSpeed = 500000;

protected int mode = 0;

protected static Map<String, String> settings = new HashMap<String, String>();

/**

* Opens an SPI interface as master

* @param dev device name

* @see list

* @webref

public SPI(String dev) {

NativeInterface.loadLibrary();

this.dev = dev;

handle = NativeInterface.openDevice("/dev/" + dev);

if (handle < 0) {

throw new RuntimeException(NativeInterface.getError(handle));

}

/**

* Closes the SPI interface

* @webref

public void close() {

NativeInterface.closeDevice(handle);

handle = 0;

}

protected void finalize() throws Throwable {

try {

close();

} finally {

super.finalize();

}

/**

* Lists all available SPI interfaces

* @return String array

* @webref

public static String[] list() {

ArrayList<String> devs = new ArrayList<String>();

File dir = new File("/dev");

File[] files = dir.listFiles();

if (files != null) {

for (File file : files) {

if (file.getName().startsWith("spidev")) {

devs.add(file.getName());

}

// listFiles() does not guarantee ordering

String[] tmp = devs.toArray(new String[devs.size()]);

Arrays.sort(tmp);

return tmp;

}

/**

* Configures the SPI interface

* @param maxSpeed maximum transmission rate in Hz, 500000 (500 kHz) is a resonable default

* @param dataOrder whether data is send with the first- or least-significant bit first (SPI.MSBFIRST or SPI.LSBFIRST, the former is more common)

* @param mode <a href="https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus#Clock_polarity_and_phase">SPI.MODE0 to SPI.MODE3</br>

* @webref

public void settings(int maxSpeed, int dataOrder, int mode) {

this.maxSpeed = maxSpeed;

this.dataOrder = dataOrder;

this.mode = mode;

}

/**

* Transfers data over the SPI bus

* @param out bytes to send

* @return bytes read in (array is the same length as out)

* @webref

public byte[] transfer(byte[] out) {

// track the current setting per device across multiple instances

String curSettings = maxSpeed + "-" + dataOrder + "-" + mode;

if (!curSettings.equals(settings.get(dev))) {

int ret = NativeInterface.setSpiSettings(handle, maxSpeed, dataOrder, mode);

if (ret < 0) {

System.err.println(NativeInterface.getError(handle));

throw new RuntimeException("Error updating device configuration");

}

settings.put(dev, curSettings);

}

byte[] in = new byte[out.length];

int transferred = NativeInterface.transferSpi(handle, out, in);

if (transferred < 0) {

throw new RuntimeException(NativeInterface.getError(transferred));

} else if (transferred < out.length) {

throw new RuntimeException("Fewer bytes transferred than requested: " + transferred);

}

return in;

}

/**

* Transfers data over the SPI bus

* @param out string to send

* @return bytes read in (array is the same length as out)

public byte[] transfer(String out) {

return transfer(out.getBytes());

}

/**

* Transfers data over the SPI bus

* @param out single byte to send

* @return bytes read in (array is the same length as out)

public byte[] transfer(int out) {

if (out < 0 || 255 < out) {

System.err.println("The transfer function can only operate on a single byte at a time. Call it with a value from 0 to 255.");

throw new RuntimeException("Argument does not fit into a single byte");

}

byte[] tmp = new byte[1];

tmp[0] = (byte)out;

return transfer(tmp);

}

processing/java/libraries/io/src/processing/io/SPI.java at master · johan718/processing · GitHub

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