.. highlight:: csharp

Serial Passthrough
==================
The `ISerialPassthrough <http://mbientlab.com/docs/metawear/csharp/1/interfaceMbientLab_1_1MetaWear_1_1Peripheral_1_1ISerialPassthrough.html>`_ interface encapsulates the 
I2C and SPI buses which can be used to communicate with more complex devices.

::

    using MbientLab.MetaWear.Peripheral;

    ISerialPassthrough serialPassthrough = metawear.GetModule<ISerialPassthrough>();

I2C
---
Reading and writing data over the I2C bus is done with the 
`ReadI2CAsync <http://mbientlab.com/docs/metawear/csharp/1/interfaceMbientLab_1_1MetaWear_1_1Peripheral_1_1ISerialPassthrough.html#aaac5c2aa669dc2095997ea0e8a01c01a>`_ and 
`WriteI2C <http://mbientlab.com/docs/metawear/csharp/1/interfaceMbientLab_1_1MetaWear_1_1Peripheral_1_1ISerialPassthrough.html#ae17d3db5c0f5a196c6fc59e7237c8da8>`_ methods 
respectively.  Note that the MeteaWear performs a register read not a raw read.

::

    // On MetaWear R boards, this reads the WHO_AM_I register from the accelerometer
    byte[] result = await serialPassthrough.ReadI2CAsync(0x1c, 0x0d, 1);
    Console.WriteLine("WHO_AM_I = " + result[0]);
    
    // Reads the ID register from the BMP280 barometer (rpro, cpro, motion)
    result = await serialPassthrough.ReadI2CAsync(0x77, 0xd0, 1);
    Console.WriteLine("bmp280 id = " + result[0]);

SPI
---
Reading and writing data over the SPI bus is done with the 
`ReadSpiAsync <http://mbientlab.com/docs/metawear/csharp/1/interfaceMbientLab_1_1MetaWear_1_1Peripheral_1_1ISerialPassthrough.html#af54c690b46430888266bc868e6468acd>`_ and 
`WriteSpi <http://mbientlab.com/docs/metawear/csharp/1/interfaceMbientLab_1_1MetaWear_1_1Peripheral_1_1ISerialPassthrough.html#a816f9b725c998adccfb40721f5fe04e6>`_ methods 
respectively.  
::

    // read registers from the BMI160 IMU (rg, rpro, c, cpro, motion, tracker)
    var result = await serialPassthrough.ReadSPIAsync(5, 10, 0, 11, 7, 3, SpiFrequency._8_MHz, 
            lsbFirst: false, data: new byte[] { 0xda });
    Console.WriteLine("bmi160 register read = " + Util.arrayToHexString(result));

Data Route
----------
Typically I2C and SPI data is passed directly to the Android device.  They can be used with a data route by creating a data producer using  
`I2C <http://mbientlab.com/docs/metawear/csharp/1/interfaceMbientLab_1_1MetaWear_1_1Peripheral_1_1ISerialPassthrough.html#ab21b74a766a5fca9b94ddc5035464652>`_ and 
`SPI <http://mbientlab.com/docs/metawear/csharp/1/interfaceMbientLab_1_1MetaWear_1_1Peripheral_1_1ISerialPassthrough.html#a0f86b924bd7e261354eb915a80d6800e>`_ respectively.  When calling 
these functions, a unique numerical value needs to be given to identify the object along with the number of bytes the object will read.  If the ``id`` 
parameter corresponds to an existing object, the ``length`` parameter is ignored and the existing object is returned instead.