// Copyright (C)2018-2023, Philip Munts dba Munts Technologies.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
namespace IO.Devices.PCA9534
{
///
/// Encapsulates PCA9534 (and similar) I2C GPIO Expanders.
///
public class Device
{
private readonly IO.Interfaces.I2C.Device dev;
private byte config;
private byte latch;
private byte[] cmd = { 0, 0 }; // I2C command buffer
private byte[] resp = { 0 }; // I2C response buffer
///
/// The number of available GPIO pins per chip.
///
public const int MAX_PINS = 8;
///
/// Input Port Register address.
///
public const byte InputPortReg = 0;
///
/// Output Port Register address.
///
public const byte OutputPortReg = 1;
///
/// Input Port Polarity Register address.
///
public const byte InputPolarityReg = 2;
///
/// Configuration Register address.
///
public const byte ConfigurationReg = 3;
///
/// Configure all pins as inputs.
///
public const byte AllInputs = 0xFF;
///
/// Configure all pins as outputs.
///
public const byte AllOutputs = 0x00;
///
/// Configure all inputs as normal polarity.
///
public const byte AllNormal = 0x00;
///
/// Turn all outputs off.
///
public const byte AllOff = 0x00;
///
/// Constructor for a PCA9534 (or similar) GPIO Expander.
///
/// I2C bus controller.
/// I2C slave address.
/// GPIO pin configuration.
/// Initial output states.
public Device(IO.Interfaces.I2C.Bus bus, int addr,
byte config = AllInputs, byte states = AllOff)
{
this.dev = new IO.Interfaces.I2C.Device(bus, addr);
this.Write(ConfigurationReg, config);
this.Write(InputPolarityReg, AllNormal);
this.Write(OutputPortReg, states);
}
///
/// Read from the specified PCA9534 device register.
///
/// Register address.
/// Register contents.
public byte Read(byte addr)
{
if (addr > ConfigurationReg)
throw new System.Exception("Invalid register address");
this.cmd[0] = addr;
this.dev.Transaction(this.cmd, 1, this.resp, 1);
return this.resp[0];
}
///
/// Write to the specified PCA9534 device register.
///
/// Register address.
/// Data to written.
public void Write(byte addr, byte data)
{
if (addr > ConfigurationReg)
throw new System.Exception("Invalid register address");
if (addr == InputPortReg)
throw new System.Exception("Cannot write to input port register");
this.cmd[0] = addr;
this.cmd[1] = data;
this.dev.Write(cmd, 2);
if (addr == ConfigurationReg)
this.config = data;
else if (addr == OutputPortReg)
this.latch = data;
}
///
/// Return actual state of the GPIO pins.
///
/// Pin states (MSB = GPIO7).
public byte Read()
{
return this.Read(InputPortReg);
}
///
/// Write all GPIO pins.
///
/// Data to write to pins (MSB = GPIO7).
public void Write(byte data)
{
this.Write(OutputPortReg, data);
}
///
/// This read-only property returns the last value written to the
/// configuration register.
///
public byte Config
{
get
{
return this.config;
}
}
///
/// This read-only property returns the last value written to the
/// output port register.
///
public byte Latch
{
get
{
return this.latch;
}
}
}
}