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Merge pull request #625 from WildernessLabs/mcp-simplification
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Remove bespoke bus abstraction in Mcp23xxx
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@adrianstevens
adrianstevens authored Apr 22, 2023
2 parents 47e30e5 + c733b8b commit 31604b6
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Showing 4 changed files with 64 additions and 126 deletions.
15 changes: 0 additions & 15 deletions ...adow.Foundation.Peripherals/ICs.IOExpanders.Mcp23xxx/Driver/Mcp23xxx.I2cMcpDeviceComms.cs
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15 changes: 0 additions & 15 deletions ...Meadow.Foundation.Peripherals/ICs.IOExpanders.Mcp23xxx/Driver/Mcp23xxx.IMcpDeviceComms.cs
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19 changes: 0 additions & 19 deletions ...adow.Foundation.Peripherals/ICs.IOExpanders.Mcp23xxx/Driver/Mcp23xxx.SpiMcpDeviceComms.cs
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141 changes: 64 additions & 77 deletions Source/Meadow.Foundation.Peripherals/ICs.IOExpanders.Mcp23xxx/Driver/Mcp23xxx.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,37 +27,35 @@ abstract partial class Mcp23xxx : IDigitalInputOutputController, ISpiDevice
/// <summary>
/// The default SPI bus speed for the device
/// </summary>
public Frequency DefaultSpiBusSpeed => _defaultSpiBusSpeed;
private static Frequency _defaultSpiBusSpeed = new Frequency(375, Frequency.UnitType.Kilohertz);
public Frequency DefaultSpiBusSpeed => new Frequency(375, Frequency.UnitType.Kilohertz);

/// <summary>
/// The SPI bus speed for the device
/// </summary>
public Frequency SpiBusSpeed
{
get => (mcpDevice as SpiMcpDeviceComms).BusSpeed;
set => (mcpDevice as SpiMcpDeviceComms).BusSpeed = value;
get => (mcpDevice as ISpiPeripheral).BusSpeed;
set => (mcpDevice as ISpiPeripheral).BusSpeed = value;
}

/// <summary>
/// The default SPI bus mode for the device
/// </summary>
public SpiClockConfiguration.Mode DefaultSpiBusMode => _defaultSpiBusMode;
private static SpiClockConfiguration.Mode _defaultSpiBusMode = SpiClockConfiguration.Mode.Mode0;
public SpiClockConfiguration.Mode DefaultSpiBusMode => SpiClockConfiguration.Mode.Mode0;

/// <summary>
/// The SPI bus mode for the device
/// </summary>
public SpiClockConfiguration.Mode SpiBusMode
{
get => (mcpDevice as SpiMcpDeviceComms).BusMode;
set => (mcpDevice as SpiMcpDeviceComms).BusMode = value;
get => (mcpDevice as ISpiPeripheral).BusMode;
set => (mcpDevice as ISpiPeripheral).BusMode = value;
}

private readonly IMcpDeviceComms mcpDevice;
private readonly IDigitalInputPort interruptPort;
private readonly IDigitalOutputPort resetPort;
private readonly IDictionary<IPin, DigitalInputPort> inputPorts;
private readonly IByteCommunications mcpDevice;
private IDigitalInputPort interruptPort;
private IDigitalOutputPort resetPort;
private IDictionary<IPin, DigitalInputPort> inputPorts;

private byte ioDirA, ioDirB;
private byte olatA, olatB;
Expand All @@ -75,9 +73,11 @@ public SpiClockConfiguration.Mode SpiBusMode
/// <param name="interruptPort">Optional interupt port, needed for input interrupts (pins 1-8)</param>
/// <param name="resetPort">Optional Meadow output port used to reset the mcp expander</param>
protected Mcp23xxx(II2cBus i2cBus, byte address,
IDigitalInputPort interruptPort = null, IDigitalOutputPort resetPort = null) :
this(new I2cMcpDeviceComms(i2cBus, address), interruptPort, resetPort)
{ }
IDigitalInputPort interruptPort = null, IDigitalOutputPort resetPort = null)
{
mcpDevice = new I2cPeripheral(i2cBus, address);
Initialize(interruptPort, resetPort);
}

/// <summary>
/// Mcpxxx base class contructor
Expand All @@ -89,28 +89,20 @@ protected Mcp23xxx(II2cBus i2cBus, byte address,
protected Mcp23xxx(ISpiBus spiBus,
IDigitalOutputPort chipSelectPort,
IDigitalInputPort interruptPort = null,
IDigitalOutputPort resetPort = null) :
this(new SpiMcpDeviceComms(spiBus, chipSelectPort, _defaultSpiBusSpeed, _defaultSpiBusMode), interruptPort, resetPort)
IDigitalOutputPort resetPort = null)
{

mcpDevice = new SpiPeripheral(spiBus, chipSelectPort, DefaultSpiBusSpeed, DefaultSpiBusMode);
Initialize(interruptPort, resetPort);
}

/// <summary>
/// Mcp23xxx base class
/// Initializes the Mcp23xxx
/// </summary>
/// <param name="device"></param>
/// <param name="interruptPort">optional interupt port, needed for input interrupts (pins 1-8)</param>
/// <param name="resetPort">Optional Meadow output port used to reset the mcp expander</param>
internal Mcp23xxx(IMcpDeviceComms device,
IDigitalInputPort interruptPort = null,
IDigitalOutputPort resetPort = null)
void Initialize(IDigitalInputPort interruptPort = null,
IDigitalOutputPort resetPort = null)
{
if (resetPort != null)
{
this.resetPort = resetPort;
ResetMcp();
}

// TODO: more interrupt
// check the interrupt mode and make sure it's correct
// raise an exception if not. also, doc in constructor what we expect from an interrupt port
Expand All @@ -120,12 +112,52 @@ internal Mcp23xxx(IMcpDeviceComms device,
interruptPort.Changed += InterruptPortChanged;
}

if (resetPort != null)
{
this.resetPort = resetPort;
ResetMcp();
}

inputPorts = new Dictionary<IPin, DigitalInputPort>();

IByteCommunications comms;
mcpDevice = device;
mcpDevice.WriteRegister(MapRegister(Registers.IODIR_IODirection, PortBank.A), 0xFF);
mcpDevice.WriteRegister(MapRegister(Registers.GPIO, PortBank.A), 0x00);
mcpDevice.WriteRegister(MapRegister(Registers.IPOL_InputPolarity, PortBank.A), 0x00);
mcpDevice.WriteRegister(MapRegister(Registers.GPINTEN_InterruptOnChange), 0x00);

Initialize();
if (NumberOfPins == 16)
{ //write the following registers as well (assume device is interleaving)
mcpDevice.WriteRegister(MapRegister(Registers.IODIR_IODirection, PortBank.B), 0xFF);
mcpDevice.WriteRegister(MapRegister(Registers.GPIO, PortBank.B), 0x00);
mcpDevice.WriteRegister(MapRegister(Registers.IPOL_InputPolarity, PortBank.B), 0x00);
mcpDevice.WriteRegister(MapRegister(Registers.GPINTEN_InterruptOnChange, PortBank.B), 0x00);
}

// save our state
ioDirA = ioDirB = 0xFF;
olatA = olatB = 0x00;

if (interruptPort != null)
{
bool intHigh = true;

if (interruptPort.Resistor == ResistorMode.InternalPullUp ||
interruptPort.Resistor == ResistorMode.ExternalPullUp)
{
intHigh = false;
}

byte iocon = 0x00;
iocon = BitHelpers.SetBit(iocon, 0x01, intHigh); //set interrupt pin to active high (true), low (false)
iocon = BitHelpers.SetBit(iocon, 0x02, false); //don't set interrupt to open drain (should be the default)

mcpDevice.WriteRegister(MapRegister(Registers.IOCON_IOConfiguration), iocon);

if (NumberOfPins == 16)
{
mcpDevice.WriteRegister(MapRegister(Registers.IOCON_IOConfiguration, PortBank.B), iocon);
}
}
}

/// <summary>
Expand Down Expand Up @@ -171,51 +203,6 @@ private void InterruptPortChanged(object sender, DigitalPortResult e)
InputChanged?.Invoke(this, new IOExpanderInputChangedEventArgs(interruptFlag, (ushort)(currentStatesB << 8 | currentStates)));
}

/// <summary>
/// Initializes the Mcp23xxx
/// </summary>
protected virtual void Initialize()
{
mcpDevice.WriteRegister(MapRegister(Registers.IODIR_IODirection, PortBank.A), 0xFF);
mcpDevice.WriteRegister(MapRegister(Registers.GPIO, PortBank.A), 0x00);
mcpDevice.WriteRegister(MapRegister(Registers.IPOL_InputPolarity, PortBank.A), 0x00);
mcpDevice.WriteRegister(MapRegister(Registers.GPINTEN_InterruptOnChange), 0x00);

if (NumberOfPins == 16)
{ //write the following registers as well (assume device is interleaving)
mcpDevice.WriteRegister(MapRegister(Registers.IODIR_IODirection, PortBank.B), 0xFF);
mcpDevice.WriteRegister(MapRegister(Registers.GPIO, PortBank.B), 0x00);
mcpDevice.WriteRegister(MapRegister(Registers.IPOL_InputPolarity, PortBank.B), 0x00);
mcpDevice.WriteRegister(MapRegister(Registers.GPINTEN_InterruptOnChange, PortBank.B), 0x00);
}

// save our state
ioDirA = ioDirB = 0xFF;
olatA = olatB = 0x00;

if (interruptPort != null)
{
bool intHigh = true;

if (interruptPort.Resistor == ResistorMode.InternalPullUp ||
interruptPort.Resistor == ResistorMode.ExternalPullUp)
{
intHigh = false;
}

byte iocon = 0x00;
iocon = BitHelpers.SetBit(iocon, 0x01, intHigh); //set interrupt pin to active high (true), low (false)
iocon = BitHelpers.SetBit(iocon, 0x02, false); //don't set interrupt to open drain (should be the default)

mcpDevice.WriteRegister(MapRegister(Registers.IOCON_IOConfiguration), iocon);

if (NumberOfPins == 16)
{
mcpDevice.WriteRegister(MapRegister(Registers.IOCON_IOConfiguration, PortBank.B), iocon);
}
}
}

/// <summary>
/// Checks if a pin exists on the Mcpxxxxx
/// </summary>
Expand Down

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