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Pi4J Plugin for the PIGPIO I/O Providers
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package com.pi4j.plugin.pigpio.provider.spi;
/*-
* #%L
* **********************************************************************
* ORGANIZATION : Pi4J
* PROJECT : Pi4J :: PLUGIN :: PIGPIO I/O Providers
* FILENAME : PiGpioSpi.java
*
* This file is part of the Pi4J project. More information about
* this project can be found here: https://pi4j.com/
* **********************************************************************
*
* This program 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 3 of the
* License, or (at your option) any later version.
*
* This program 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 General Lesser Public License for more details.
*
* You should have received a copy of the GNU General Lesser Public
* License along with this program. If not, see
* .
* #L%
*/
import com.pi4j.context.Context;
import com.pi4j.exception.InitializeException;
import com.pi4j.io.exception.IOException;
import com.pi4j.io.spi.*;
import com.pi4j.library.pigpio.PiGpio;
/**
* PiGpioSpi class.
*
* @author Robert Savage (http://www.savagehomeautomation.com)
* @version $Id: $Id
*/
public class PiGpioSpi extends SpiBase implements Spi {
protected final PiGpio piGpio;
protected final int handle;
protected static int SPI_BUS_MASK = 0x0100;
protected static int SPI_MODE_MASK = 0x0003;
/**
* Constructor for PiGpioSpi.
*
* @param piGpio a {@link com.pi4j.library.pigpio.PiGpio} object.
* @param provider a {@link com.pi4j.io.spi.SpiProvider} object.
* @param config a {@link com.pi4j.io.spi.SpiConfig} object.
*
* ------------------------------------------------------------------
* spiFlags consists of the least significant 22 bits.
* ------------------------------------------------------------------
* 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
* b b b b b b R T n n n n W A u2 u1 u0 p2 p1 p0 m m
*
* [mm] defines the SPI mode.
* Warning: modes 1 and 3 do not appear to work on the auxiliary SPI.
*
* Mode POL PHA
* 0 0 0
* 1 0 1
* 2 1 0
* 3 1 1
*
* [px] is 0 if CEx is active low (default) and 1 for active high.
* [ux] is 0 if the CEx GPIO is reserved for SPI (default) and 1 otherwise.
* [A] is 0 for the main SPI, 1 for the auxiliary SPI.
* [W] is 0 if the device is not 3-wire, 1 if the device is 3-wire. Main SPI only.
* [nnnn] defines the number of bytes (0-15) to write before switching the MOSI line to MISO to read data.
* This field is ignored if W is not set. Main SPI only.
* [T] is 1 if the least significant bit is transmitted on MOSI first, the default (0) shifts the
* most significant bit out first. Auxiliary SPI only.
* [R] is 1 if the least significant bit is received on MISO first, the default (0) receives the most
* significant bit first. Auxiliary SPI only.
* [bbbbbb] defines the word size in bits (0-32). The default (0) sets 8 bits per word. Auxiliary SPI only.
*
*/
public PiGpioSpi(PiGpio piGpio, SpiProvider provider, SpiConfig config) {
super(provider, config);
// set local reference instance
this.piGpio = piGpio;
// get configured SPI bus
SpiBus bus = config.bus();
// get configured SPI mode
SpiMode mode = config.mode();
// the default value for 'flags' is zero
int flags = 0;
// if 'flags' were provided in the SPI config, then accept them
if(config().flags() != null){
flags = config().flags().intValue();
}
// only SPI BUS_0 and AUX SPI BUS_1 are supported by PiGPIO
if(bus.getBus() > 1){
throw new IOException("Unsupported BUS by PiGPIO SPI Provider: bus=" + bus.toString());
}
// channel/address (chip-select) #2 is not supported on SPI_BUS_0 by PiGPIO
if(bus == SpiBus.BUS_0 && config.address() == 2) {
throw new IOException("Unsupported SPI channel (chip select) on SPI BUS_0 bus: address=" + config.address() );
}
// Comments on the PiGPIO web https://abyz.me.uk/rpi/pigpio/cif.html#spiOpen as follows:
// "Warning: modes 1 and 3 do not appear to work on the auxiliary SPI."
// SPI MODE_1 and MODE_3 are not supported on the AUX SPI BUS_1 by PiGPIO
if(bus == SpiBus.BUS_1 && (mode == SpiMode.MODE_1 || mode == SpiMode.MODE_3)) {
throw new IOException("Unsupported SPI mode on AUX SPI BUS_1: mode=" + mode.toString());
}
if(config.busUserProvided()) { // user provided, overwrite flags
// update flags value with BUS bit ('A' 0x0000=BUS0; 0x0100=BUS1)
if (bus == SpiBus.BUS_0) {
flags = (flags & (0xFFFFFFFF ^ SPI_BUS_MASK)); // clear AUX bit
} else if (bus == SpiBus.BUS_1) {
flags = (flags & (0xFFFFFFFF ^ SPI_BUS_MASK)) | SPI_BUS_MASK; // set AUX bit
}
}
if(config.modeUserProvided()) { // user provided, overwrite flags
// update flags value with MODE bits ('mm' 0x03)
flags = (flags & (0xFFFFFFFF ^ SPI_MODE_MASK)) | mode.getMode(); // set MODE bits
}
// create SPI instance of PiGPIO SPI
this.handle = piGpio.spiOpen(
config.address(),
config.baud(),
flags);
// set open state flag
this.isOpen = true;
}
/** {@inheritDoc} */
@Override
public Spi initialize(Context context) throws InitializeException {
super.initialize(context);
return this;
}
/** {@inheritDoc} */
@Override
public void close() {
piGpio.spiClose(this.handle);
super.close();
}
// -------------------------------------------------------------------
// DEVICE TRANSFER FUNCTIONS
// -------------------------------------------------------------------
/** {@inheritDoc} */
@Override
public int transfer(byte[] write, int writeOffset, byte[] read, int readOffset, int numberOfBytes) {
return piGpio.spiXfer(this.handle, write, writeOffset, read, readOffset, numberOfBytes);
}
// -------------------------------------------------------------------
// DEVICE WRITE FUNCTIONS
// -------------------------------------------------------------------
/** {@inheritDoc} */
@Override
public int write(byte b) {
return piGpio.spiWriteByte(this.handle, b);
}
/** {@inheritDoc} */
@Override
public int write(byte[] data, int offset, int length) {
return piGpio.spiWrite(this.handle, data, offset, length);
}
// -------------------------------------------------------------------
// RAW DEVICE READ FUNCTIONS
// -------------------------------------------------------------------
/** {@inheritDoc} */
@Override
public int read() {
return piGpio.spiReadByte(this.handle);
}
/** {@inheritDoc} */
@Override
public int read(byte[] buffer, int offset, int length) {
return piGpio.spiRead(this.handle, buffer, offset, length);
}
}