LINUX-I2C

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VAR-SOM-MX8 I2C

Available I2C buses

List of available I2C buses on VAR-SOM-MX8

# ls -l /dev/i2c-*
crw------- 1 root root 89, 0 Jun 12 12:43 /dev/i2c-0
crw------- 1 root root 89, 1 Jun 12 12:43 /dev/i2c-1
crw------- 1 root root 89, 4 Jun 12 12:43 /dev/i2c-4

System class on VAR-SOM-MX8:

# ls /sys/class/i2c-dev/
i2c-0  i2c-1  i2c-4


List of available I2C buses on SPEAR-MX8

# ls -l /dev/i2c-*
crw------- 1 root root 89, 0 Jul 16 12:22 /dev/i2c-0
crw------- 1 root root 89, 1 Jul 16 12:22 /dev/i2c-1
crw------- 1 root root 89, 2 Jul 16 12:22 /dev/i2c-2
crw------- 1 root root 89, 4 Jul 16 12:22 /dev/i2c-4
crw------- 1 root root 89, 5 Jul 16 12:22 /dev/i2c-5
crw------- 1 root root 89, 6 Jul 16 12:22 /dev/i2c-6


System class on SPEAR-MX8:

# ls /sys/class/i2c-dev/
i2c-0  i2c-1  i2c-2  i2c-4  i2c-5  i2c-6

I2C devices per bus

Scan bus 0:

# i2cdetect -y -r 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- UU -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- 52 53 -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         

Scan bus 1:

# i2cdetect -y -r 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- UU UU -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         

Scan bus 4:

# i2cdetect -y -r 4
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- 54 55 -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         

When the device is marked with "UU" it means that a driver is using it.
When the device is marked with numbers it means that no driver is using it.

Reading / Writing from an I2C device

Variscite includes I2CTools as a part of the default file system build, examples of optional commands:
i2cdump - dump the content of an I2C device
i2cset - write a single character to an I2C device
i2cget - read a single character to an I2C device

In addition follow 'C' code example as describe in the linux kernel documentation : https://www.kernel.org/doc/Documentation/i2c/dev-interface

Variscite's system integrated I2C devices

Note: Do not write to Variscite's on-SOM EEPROM or you will damage the SOM!


Variscite devices on VAR-SOM-MX8:

I2C-0 0x1a - Audio codec on SOM
I2C-0 0x52 - EEPROM on SOM. Don't modify!
I2C-0 0x53 - EEPROM on SOM. Don't modify!

I2C-1 0x20 – GPIO expander on carrier board
I2C-1 0x3c – MIPI-CSI camera on expansion board
I2C-1 0x3d – USB Type C controller on carrier board

I2C-4 0x38 – Capacitive touch controller on kit display
I2C-4 0x54 - EEPROM on carrier board
I2C-4 0x55 - EEPROM on carrier board
I2C-4 0x68 – RTC on carrier board


Variscite devices on SPEAR-MX8:

I2C-0 0x38 – Capacitive touch controller on kit display
I2C-0 0x54 - EEPROM on carrier board
I2C-0 0x55 - EEPROM on carrier board
I2C-0 0x68 – RTC on carrier board

I2C-1 0x3d – USB Type C controller on carrier board

I2C-2 0x08 – USB3 Hub

I2C-4 0x1a - Audio codec on SOM

I2C-5 0x3c – MIPI-CSI camera on expansion board

I2C-6 0x3c – MIPI-CSI camera on expansion board