i2c

Probes the I2C device.

Function Arguments

Name	Type	Description
bus_number	str, None	(optional; default: None) The I2C bus number. Every bus will be scanned if it is not assigned. If the bus is behind EC, then it should have “EC-” prefix. For example: “EC-0”
bus_path	str, None	(optional; default: None) The realpath of the I2C bus sysfs node. Ignored if bus_number argument is given.
bus_name	str, None	(optional; default: None) The name of the I2C bus sysfs node. Ignored if bus_number argument is given.
addr	str, None	(optional; default: None) The address of the device. Every address between 0x03 and 0x77 will be scanned if it is not assigned.
use_r_flag	bool	(optional; default: False) Use SMBus “read byte” commands for probing.

Description

This function probes a specific bus/address to check whether an I2C device is connected there or not.

The probed result for a single I2C device is a dictionary which contains at least two entries, one is bus_number and the other one is addr.

Examples

Let’s say we’ve already known that the address of I2C camera X is 0x24 but we don’t know which bus that camera is connected. A not 100% reliable way to verify whether camera X is installed or not on the device is to write the probe statement

{
  "eval": {
    "i2c": {
      "addr": "0x24"
    }
  }
}

The function will try to probe address 0x24 on all I2C buses. If camera X is found at bus 2, we will have below probed results:

[
  {
    "addr": "0x24",
    "bus_number": "2"
  }
]

Otherwise the probed results might be just an empty list. Howerver, it’s possible that another I2C device has the address number 0x24 on another bus too. In this case, the probe statement above will lead to a false positive result.