Reply To: I2C communication PCF8574AP

[Bartłomiej Drozd]

unfortunetly, it is not workking… i found source of sending function

               /// <summary>
		/// Write and read an array of bytes to the sensor
		/// </summary>
		/// <returns>The bytes that was read</returns>
		/// <param name="register">Register to write to.</param>
		/// <param name="data">Byte array to write</param>
		/// <param name="rxLength">Length of the expected reply</param>
        protected byte[] WriteAndRead (byte register, byte[] data, int rxLength)
		{
			if (rxLength > BufferSize)
				throw new ArgumentOutOfRangeException("I2C Receive Buffer only holds " + BufferSize + " bytes");
			if (data.Length > BufferSize) {
				throw new ArgumentOutOfRangeException("I2C Write Buffer only holds " + BufferSize + " bytes");
			}
			bool dataReady = false;
			int replyIndex = 0;
			byte[] writeData = new byte[BufferSize];//30
			Array.Copy (data, 0, writeData, 0, data.Length);
			ByteArrayCreator command = new ByteArrayCreator ();
			command.Append ((int)-1);
			command.Append ((byte)this.port);
			command.Append ((byte)1);//repeat
			command.Append ((short)0);//time
			command.Append ((byte)(data.Length + 2));//length of write data
			command.Append ((byte)((byte)I2CAddress >> 1));
			command.Append (register);
			command.Append(writeData);
			command.Append ((byte)-rxLength);
			replyIndex = command.Data.Length;
			command.Append (new byte[BufferSize]);//make room for reply
			byte[] i2cData = command.Data;
			while (!dataReady) {
				unchecked {
					I2CDevice.IoCtl ((Int32)I2CIOSetup, i2cData);
				}
				int status = BitConverter.ToInt32 (i2cData, 0);
				if (status < 0) {
					throw new Exception ("I2C I/O error");
				}
				if (status == 0) {
					byte[] reply = new byte[rxLength];
					if (rxLength > 0) {
						Array.Copy(i2cData,replyIndex, reply,0, rxLength);
					}
					return reply;
				}
			}
        	throw new TimeoutException("I2C timeout");
    	}

maybe this should help…