Example I2C bus probes¶
Objective¶
The goal of this wiki page is to demonstrate the i2cdetect command that can be used to probe an I2C bus and verify that all the devices you expect to be present are responding.
Steps¶
The i2cdetect can list the I2C buses that are present and identify which devices are responding to commands.
As noted in the manual page for i2cdetect:
This program can confuse your I2C bus, cause data loss and worse!
So use with care.
- List the buses that are present:
root@mitysom-am57x:~# i2cdetect -l i2c-4 i2c OMAP I2C adapter I2C adapter i2c-0 i2c OMAP I2C adapter I2C adapter
Note that the names i2c-0 and i2c-4 correspond to i2c1 and i2c5 on the schematics. - Probe the devices on i2c-0. This bus represents the chips on the SOM.
root@mitysom-am57x:~# i2cdetect -r -y 0 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: -- -- -- -- -- UU -- -- -- -- -- -- -- -- -- -- 50: UU -- -- -- -- -- -- -- UU UU UU 5b -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- --- The "UU" indicates that the probing was skipped because the address is being used by a driver. This usually indicates a chip is probably present.
- The 5b indicates there is a chip at address 0x5b but a driver is not using the chip. In this case, the 5b is the
- Probe the devices on i2c-4. This bus is for chips on the dev-kit board.
root@mitysom-am57x:~# i2cdetect -r -y 4 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: -- -- -- -- -- -- -- 47 -- -- -- -- -- -- -- -- 50: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- UU -- 70: -- -- -- -- -- -- -- --
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