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[RTL8722CSM] [RTL8722DM] I2C - Send and Receive
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.. role:: raw-html(raw)
   :format: html

:raw-html:`<p style="color:#E67E22; font-size:24px">`
**Materials**
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* AmebaD[AMB21 / AMB22] x 1
* Arduino UNO x 1

:raw-html:`<p style="color:#E67E22; font-size:24px">`
**Steps**
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I2C is a very common module on microcontrollers, it only takes 2 wire and able to achieve data rate at up to 3.4Mbps. It works in master-slave model and a master can simultaneously connect to up to 128 slaves, making it a very versatile communication protocol between microcontroller and sensor.

Here we are going to use Ameba as an I2C master and Arduino UNO as a slave to achieve I2C send and recv.

Before connection, make sure to upload the *“Examples -> Wire -> Slave_receiver”* example code to Arduino UNO.

Connection is shown as follows, here we are using PA_26 as SDA pin and PA_25 as SCL.

.. note::
   There is currently 1 set of I2C available to MicroPython user, they are

.. table:: 
   :align: center

   ========= =========== ===========
   Unit      SDA         SCL
   ========= =========== ===========
   0         PA_26           PA_25
   ========= =========== ===========

|image1|

Then copy and paste the following code line by line into REPL to see their effects.

.. code-block:: python
   :linenos:

   from machine import Pin, I2C
   i2c = I2C(scl = "PA_25", sda = "PA_26", freq=100000) # configure I2C with pins and freq. of 100KHz
   i2c.scan()
   i2c.writeto(8, 123) # send 1 byte to slave with address 8
   i2c.readfrom(8, 6) # receive 6 bytes from slave

.. |image1| image:: /media/ambd_micropython/examples/imageI2C.jpg
   :width: 1540
   :height: 1051
   :scale: 50 %