patch-2.3.34 linux/Documentation/i2c/i2c-protocol

• Lines: 47
• Date: Thu Dec 16 13:59:38 1999
• Orig file: v2.3.33/linux/Documentation/i2c/i2c-protocol
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.33/linux/Documentation/i2c/i2c-protocol linux/Documentation/i2c/i2c-protocol
@@ -0,0 +1,46 @@
+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