A while back I wrote a post about some problems I was having with a Silicon Labs Si7005 device and now I have had some time to package up the code.

My code strobes the I2C SDA line and then initiates a request that will always fail, from there on everything works as expected.

public SiliconLabsSI7005(byte deviceId = DeviceIdDefault, int clockRateKHz = ClockRateKHzDefault, int transactionTimeoutmSec = TransactionTimeoutmSecDefault)
{
   this.deviceId = deviceId;
   this.clockRateKHz = clockRateKHz;
   this.transactionTimeoutmSec = transactionTimeoutmSec;

   using (OutputPort i2cPort = new OutputPort(Pins.GPIO_PIN_SDA, true))
   {
      i2cPort.Write(false);
      Thread.Sleep(250);
   }

   using (I2CDevice device = new I2CDevice(new I2CDevice.Configuration(deviceId, clockRateKHz)))
   {
      byte[] writeBuffer = { RegisterIdDeviceId };
      byte[] readBuffer = new byte[1];

      // The first request always fails
      I2CDevice.I2CTransaction[] action = new I2CDevice.I2CTransaction[] 
      { 
         I2CDevice.CreateWriteTransaction(writeBuffer),
         I2CDevice.CreateReadTransaction(readBuffer)
      };

      if( device.Execute(action, transactionTimeoutmSec) == 0 )
      {
         //   throw new ApplicationException("Unable to send get device id command");
      }
   }
}

This is how the driver should be used in an application

public static void Main()
{
   SiliconLabsSI7005 sensor = new SiliconLabsSI7005();

   while (true)
   {
      double temperature = sensor.Temperature();

      double humidity = sensor.Humidity();

      Debug.Print("T:" + temperature.ToString("F1") + " H:" + humidity.ToString("F1"));

      Thread.Sleep(5000);
      }
   }

I have added code to catch failures and there is a sample application in the project. For a project I’m working on I will modify the code to use one of the I2C sharing libraries so I can have a number of devices on the bus