.. highlight:: cpp

I2C
===
The I2C module allows you to directly communicate with a sensor via the I2C bus.  I2C functions are defined in the 
`i2c.h <https://mbientlab.com/docs/metawear/cpp/latest/i2c_8h.html>`_ header file.

Read
----
I2C reads are executed by calling `mbl_mw_i2c_read <https://mbientlab.com/docs/metawear/cpp/latest/i2c_8h.html#a71938bd42df677ef8023f304fba22af7>`_.  
When calling the function, you need to specify: 

* Device address
* Register address
* Number of bytes
* User defined id value identifying the operation

::

    #include "metawear/core/datasignal.h"
    #include "metawear/sensor/i2c.h"
    
    void i2c_read(MblMwMetaWearBoard* board) {
        // Assign id=10 to this specific i2c read
        static uint8_t read_id = 10;
        static auto i2c_data = [](const MblMwData* data) -> void {
            printf("WHO_AM_I= %x", ((uint8_t*) data->value)[0]);
        };
    
        auto read_signal = mbl_mw_i2c_get_data_signal(board, 1, read_id);
        mbl_mw_datasignal_subscribe(read_signal, i2c_data);
        // Read WHO_AM_I register from the MetaWear R accelerometer
        mbl_mw_i2c_read(board, 0x1c, 0xd, 1, read_id);
    }

Write
-----
Writing data through the I2C bus is handled with the 
`mbl_mw_i2c_write <https://mbientlab.com/docs/metawear/cpp/latest/i2c_8h.html#a484a0f6338a2d90eb9167283c6859165>`_ function.  You will need to specify:
 
* Device address
* Register address
* Data to send

::

    #include "metawear/sensor/i2c.h"
    
    void i2c_write(MblMwMetaWearBoard* board) {
        // Write to the ctrl_meas register on the RPro/CPro barometer
        uint8_t ctrl_meas= 0x37;
        mbl_mw_i2c_write(board, 0x77, 0xf4, &ctrl_meas, 1);
    }