I2C in BBB

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1

Hello,
I have two questions/doubts in beaglebone black I2c.

  1. Is i2cdev module is installed by default ? I checked lsmod and modprobe i2cdev, I didn’t find it but /dev/i2c-0 and /dev/i2c-1 is present.

  2. If it installed, do I need to do any configuration to use I2c ? (in userspace)

Thanks in advance :slight_smile:

2

Hi,
1 - i2c was installed by default in my install of the latest factory image…some notes though on the the i2c busses:
i2c-0 is used by some on-board devices
i2c-1 does not yet seem to be supported by the kernel
i2c-2 actually uses the kernel’s /dev/i2c-1 located on p9 with pins 19,20

2 - there are some useful tools for i2c which were from the following link http://elinux.org/Interfacing_with_I2C_Devices:

  • list chips on i2c bus (should report a device): i2cdetect -r
  • get data from i2c device (should give data): i2cget [register] [b|w]
    eg for a TMP102 device with ADDR0 pin tied to GND on I2C-2:
    “i2cdetect -r 1” shows device at 0x48
    “i2cget 1 0x48 0 w” shows 0xa019 = 0x19a = 25.6C = 78F

Hopefully this is some help,
Dale

3

Hi Dale,

You are absolutely right. I can see my EEPROM address 50 by executing "i2cdetect -r 1", thank you for the help :slight_smile:

4

It’s worth noting that the i2c driver names the /dev/ files. So it’s only incidental that /dev/i2c-1 points to the i2c-2 pins. Generating a new device tree that configures all three i2c peripherals should cause a /dev/i2c-2 to get created.

5

What are the default pins for the i2c-0 bus?