/// <summary>
///
/// </summary>
/// <param name="address"></param>
/// <returns></returns>
public byte ReadByte(byte address)
{
//Console.WriteLine(" spiBufTx = {0} {1} {2}", CMD_READ, address, 0);
Marshal.Copy(new byte[] { CMD_READ, address, 0 }, 0, this._txBufferPtr, HardwareSpiDevice.TxRxBufferLength);
Marshal.Copy(new byte[] { 0, 0, 0 }, 0, this._rxBufferPtr, HardwareSpiDevice.TxRxBufferLength);
// build the command
var cmd = SpiDev.SPI_IOC_MESSAGE(1);
// build the spi transfer structure
var spi = new SpiDev.spi_ioc_transfer
{
tx_buf = (UInt64)this._txBufferPtr.ToInt64(),
rx_buf = (UInt64)this._rxBufferPtr.ToInt64(),
len = HardwareSpiDevice.TxRxBufferLength,
delay_usecs = this.SpiDelay,
speed_hz = this.MaxSpeedHz,
bits_per_word = (byte)this.BitsPerWord
};
// call the native method
var result = IoCtl.ioctl(this.DeviceHandle, cmd, ref spi);
if (result < 0)
{
var error = Mono.Unix.Native.Stdlib.GetLastError();
}
// return the result. every byte transmitted results in a
// data or dummy byte received, so we have to skip the
// leading dummy bytes to read out actual data bytes.
var bufOut = new byte[HardwareSpiDevice.TxRxBufferLength];
Marshal.Copy(this._txBufferPtr, bufOut, 0, bufOut.Length);
Marshal.Copy(this._rxBufferPtr, bufOut, 0, bufOut.Length);
return bufOut[2];
}
/// <summary>
/// Write a value to the SPI bus.
/// </summary>
/// <param name="address"></param>
/// <param name="value"></param>
public void WriteByte(byte address, byte value)
{
Marshal.Copy(new byte[] { CMD_WRITE, address, value }, 0, this._txBufferPtr, HardwareSpiDevice.TxRxBufferLength);
Marshal.Copy(new byte[] { 0, 0, 0 }, 0, this._rxBufferPtr, HardwareSpiDevice.TxRxBufferLength);
// build the command
var cmd = SpiDev.SPI_IOC_MESSAGE(1);
// build the spi transfer structure
var spi = new SpiDev.spi_ioc_transfer
{
tx_buf = (UInt64)this._txBufferPtr.ToInt64(),
rx_buf = (UInt64)this._rxBufferPtr.ToInt64(),
len = HardwareSpiDevice.TxRxBufferLength,
delay_usecs = this.SpiDelay,
speed_hz = this.MaxSpeedHz,
bits_per_word = (byte)this.BitsPerWord
};
// call the native method
var result = IoCtl.ioctl(this.DeviceHandle, cmd, ref spi);
if (result < 0)
{
var error = Mono.Unix.Native.Stdlib.GetLastError();
}
}
public static extern int ioctl(int fd, uint cmd, ref SpiDev.spi_ioc_transfer arg);
