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--- documentation:protocols:i2c:i2c-tools_shell [2026/10/08 13:12] – removed - external edit (Unknown date) 127.0.0.1
+++ documentation:protocols:i2c:i2c-tools_shell [2026/10/09 11:11] (current) – [i2cdump] chris
@@ Line 1: / Line 1: @@
+====== Bash Shell Interface for I2C ======
+On the kernel level, I2C communication is handled by the ''i2c-dev'' kernel driver.
+On the lowest level, the bus is seen as a file and using a file descriptor one can
+read from it or write to it. The shell interface is a set of compiled programs that
+wrap this functionality for specific uses at a higher level. The intended use is
+interactive debugging to see if something works or not. For programmatic use it's
+better to take a look at the [[.:i2c-tools_API|C API]] for C/C++ and the
+[[.:smbus2|smbus2]] library for Python.
+These programs are part of the ''i2c-tools'' package that usually comes preinstalled
+in most Linux distributions.
+===== i2cdetect =====
+Detects I2C chips. Use: ''i2cdetect [options] i2cbus [first_addr last_addr]''. Special flags that don't require a given i2cbus are ''-V'' that prints the current version and ''-l''.
+  * ''i2cdetect -l'' to list busses. To access each buss you have to used it's number (''i2c-{NUM}'') or the full string name.
+  * ''-q'' and ''-r'' options are to use quick write and receive byte commands for probing. They can corrupt certain IC chips.
+  * ''-F'' displays the list of functionalities available on the bus.
+===== i2cdump =====
+Examines registers on the I2C bus. Use: ''i2cdump [options] i2cbus address [mode [bank [bankreg]]]''
+  * ''i2cbus'': One of the buses represented by the number or string name from ''i2cdetect -l''.
+  * ''-r first-last'': Limit the range of registers being accessed. Incompatible with ''s''.
+  * ''address'': The address of the IC chip on the bus.
+  * ''mode'': Chooses the mode to access the register as a single byte, a double byte word or a block. If not provided, defaults to single byte without PEC. Options are listed below:
+    * ''b'': Single byte (default).
+    * ''w'': Word.
+    * ''i'': I2C block.
+    * ''c'': Consecutive block. Useful for ICs with automatic increment, like EEPROMs.
+    * ''W'': Word, but the command will only be issued on even addresses. Also useful for EEPROMs.
+    * ''s'': SMBus block. Avoid it, it's deprecated.
+    * ''p'': Can be appended on the mode parameter (not on ''i'' and ''W'') to enable Packet Error Checking (PEC).
+  * ''bank''/''bankreg'': Used on Winbond and Asus chips. ''bank'' is an integer from 0 to 7, and ''bankreg'' an integer from 0x00 to 0xff with a default of 0x4e.
+Use of ''i2cdump'' is not advised unless you have intimate knowledge of the IC you're accessing. It's very easy to corrupt stuff.
+===== i2cget =====
+===== i2cset =====
+===== i2ctransfer =====

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