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This document describes the i2c protocol. Or will, when it is finished :-)
Key to symbols
==============
S (1 bit) : Start bit
P (1 bit) : Stop bit
Rd/Wr (1 bit) : Read/Write bit. Rd equals 1, Wr equals 0.
A, NA (1 bit) : Accept and reverse accept bit.
Addr (7 bits): I2C 7 bit address. Note that this can be expanded as usual to
get a 10 bit I2C address.
Comm (8 bits): Command byte, a data byte which often selects a register on
the device.
Data (8 bits): A plain data byte. Sometimes, I write DataLow, DataHigh
for 16 bit data.
Count (8 bits): A data byte containing the length of a block operation.
[..]: Data sent by I2C device, as opposed to data sent by the host adapter.
Simple send tranaction
======================
This corresponds to i2c_master_send.
S Addr Wr [A] Data [A] Data [A] ... [A] Data [A] P
Simple receive transaction
===========================
This corresponds to i2c_master_recv
S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P
Combined tranactions
====================
This corresponds to i2c_transfer
They are just like the above transactions, but instead of a stop bit P
a start bit S is sent and the transaction continues. An example of
a byte read, followed by a byte write:
S Addr Rd [A] [Data] NA S Addr Wr [A] Data [A] P
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