Simple send transaction
=======================
-This corresponds to i2c_master_send()::
+Implemented by i2c_master_send()::
S Addr Wr [A] Data [A] Data [A] ... [A] Data [A] P
Simple receive transaction
==========================
-This corresponds to i2c_master_recv()::
+Implemented by i2c_master_recv()::
S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P
Combined transactions
=====================
-This corresponds to i2c_transfer().
+Implemented by i2c_transfer().
They are just like the above transactions, but instead of a stop
condition P a start condition S is sent and the transaction continues.