I2C

This guide will show you how to test the I2C interface on the phyCORE-i.MX8X development kit.

Note

The phyCORE-i.MX8X SOM supports up to 9x I2C interfaces by default.

Only four of these are supported on the phyCORE-i.MX8X carrier board and three of those four are reserved for specific interfaces (2x for the MIPI display 1x for the MIPI camera interfaces).

I2C Paths
Interface	Sysfs Path
CSI0_I2C0	/dev/i2c-16
DSI0_I2C0	/dev/i2c-17
DSI1_I2C0	/dev/i2c-18
I2C1	/dev/i2c-19

Requirements

Female to Female Jumper Wires
I2C device ( Accelerometer )

Hardware Setup

Connecting the I2C Device
I2C Device Signal	Carrier Board Signal	Carrier Board Connector-Pin
VCC	VCC_3V3	X60 - Pin 1
SCL	X_I2C1_SCL	X59 - Pin 7
SDA	X_I2C1_SDA	X59 - Pin 8
GND	GND	X59 - Pin 9

Warning

Be sure that the development kit is powered off when connecting the I2C device.

Using I2C1

Power on the development kit and boot into Linux.
List the available I2C devices. There will be a few devices that pop up but /dev/i2c-19 corresponds to the I2C1 interface.
Target (Linux)
```
ls /dev/i2c*
```
Expected Output
```
/dev/i2c-16  /dev/i2c-17  /dev/i2c-18  /dev/i2c-19
```
Use the “i2cdetect” command to scan the bus for devices. This command outputs the address of all devices on the I2C1 bus.

Note

UU indicates that the device connected is tied to a kernel driver and you will be unable to communicate with the device via i2c commands (i2cset and i2cget).

Target (Linux)

i2cdetect -y -r 16

Expected Output

       0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
-- -- -- -- -- -- -- UU -- -- -- -- -- -- -- --
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3f
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
-- UU UU -- -- -- -- -- -- 59 -- -- -- -- -- --
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

The detected interfaces should match with the devices connected to I2C1 on the development kit.

I2C Interface Addresses
Interface	Address (7-bit
GPIO Expander	0x20
USB-C Controller	0x3F
EEPROM	0x51, 0x59
RTC	0x52
Audio	0x0A

Note

The EEPROM M24C32 has two different addresses (0x51 and 0x59) but one has been reserved in the device tree.