/// <summary>
/// Export the GPIO setting the direction.
/// </summary>
/// <param name="pin">
/// The pin to export.
/// </param>
/// <param name="mode">
/// The I/0 mode of the pin.
/// </param>
private static void internal_ExportPin(Int32 pin, PinMode mode)
{
Initialize();
// If the pin is already exported, check it's in the proper direction.
if (ExportedPins.ContainsKey(pin))
{
// If the direction matches, return out of the function. If not,
// change the direction.
if (ExportedPins[pin] == mode)
{
return;
}
}
// Set the direction on the pin and update the exported list.
// BCM2835_GPIO_FSEL_INPT = 0
// BCM2835_GPIO_FSEL_OUTP = 1
uint pindir = (mode == PinMode.IN) ? (uint)0 : (uint)1;
UnsafeNativeMethods.bcm2835_gpio_fsel((uint)pin, pindir);
if (mode == PinMode.IN)
{
// BCM2835_GPIO_PUD_OFF = 0b00 = 0
// BCM2835_GPIO_PUD_DOWN = 0b01 = 1
// BCM2835_GPIO_PUD_UP = 0b10 = 2
UnsafeNativeMethods.bcm2835_gpio_set_pud((uint)pin, 0);
}
ExportedPins[pin] = mode;
}
/// <summary>
/// Unexports an exported pin.
/// </summary>
/// <param name="pin">
/// The pin to unexport.
/// </param>
private static void internal_UnexportPin(Int32 pin)
{
Debug.WriteLine("Unexporting pin " + pin.ToString());
// TODO Somehow reverse what we did in internal_ExportPin? Is there
// a way to "free" the pin in the libbcm2835 library?
UnsafeNativeMethods.bcm2835_gpio_write((uint)pin, (uint)PinState.Low);
UnsafeNativeMethods.bcm2835_gpio_fsel((uint)pin, (uint)PinMode.TRI);
ExportedPins.Remove(pin);
}
/// <summary>
/// Destroy this GPIO factory.
/// </summary>
public static void Destroy()
{
if (ExportedPins != null)
{
if (ExportedPins.Count > 0)
{
foreach (Int32 pin in ExportedPins.Keys)
{
internal_UnexportPin(pin);
}
ExportedPins.Clear();
}
}
UnsafeNativeMethods.bcm2835_close();
}
/// <summary>
/// Exports the GPIO setting the direction. This creates the
/// /sys/class/gpio/gpioXX directory.
/// </summary>
/// <param name="pin">
/// The GPIO pin.
/// </param>
/// <param name="mode">
/// The I/O mode.
/// </param>
/// <param name="pinnum">
/// The pin number.
/// </param>
/// <param name="pinname">
/// The name of the pin.
/// </param>
private static void internal_ExportPin(Int32 pin, PinMode mode, String pinnum, String pinname)
{
String pinpath = GPIO_PATH + "gpio" + pinnum;
String m = Enum.GetName(typeof(PinMode), mode);
// If the pin is already exported, check it's in the proper direction.
if (ExportedPins.ContainsKey(pin))
{
// If the direction matches, return out of the function. If not,
// change the direction.
if (ExportedPins[pin] == mode)
{
return;
}
else
{
// Set the direction on the pin and update the exported list.
File.WriteAllText(pinpath + "/direction", m);
ExportedPins[pin] = mode;
return;
}
}
// Export.
if (!Directory.Exists(pinpath))
{
Debug.WriteLine("Exporting pin " + pinnum);
File.WriteAllText(GPIO_PATH + "export", pinnum);
}
// Set I/O direction.
Debug.WriteLine("Setting direction on pin " + pinname + "/gpio" + pin.ToString() + " as " + m);
File.WriteAllText(pinpath + "/direction", m);
// Update the pin.
ExportedPins[pin] = mode;
}
/// <summary>
/// Unexport the GPIO. This removes the /sys/class/gpio/gpioXX directory.
/// </summary>
/// <param name="pin">
/// The GPIO pin to unexport.
/// </param>
/// <param name="gpioNum">
/// The GPIO number associated with the pin.
/// </param>
private static void internal_UnexportPin(Int32 pin, String gpioNum)
{
Debug.WriteLine("Unexporting pin " + pin.ToString());
File.WriteAllText(GPIO_PATH + "unexport", gpioNum);
ExportedPins.Remove(pin);
}
