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Table of Contents
I2C
Introduction
This document mainly introduces the usage of I2C bus on 40-Pin Header.
I2C Information
| I2C | PIN & GPIO(#number) | DT Overlays Node | Bus Number | Device Node | |
|---|---|---|---|---|---|
| VIM1/2 | I2C A | SCL(22) - GPIODV_25 (#474) SDA (23) - GPIODV_24 (#473) | i2c0 | 0 | /dev/i2c-0 |
| I2C B | SCL(25) - GPIODV_27 (#476) SDA(26) - GPIODV_26 (#475) | - | 1 | /dev/i2c-1 | |
| VIM3/3L | I2CM 3 | SCL(22) - GPIOA_15 (#475) SDA(23) - GPIOA_14 (#474) | i2c3 | 3 | /dev/i2c-3 |
| I2C AO | SCL(25) - GPIOAO_2 (#498) SDA(26) - GPIOAO_3 (#499) | - | 4 | /dev/i2c-4 | |
| VIM4 | I2CM F | SCL(22) - GPIOY_17 (#501) SDA (23) - GPIOY_18 (#502) | i2cm_f | 5 | /dev/i2c-5 |
| I2CM A | SCL(25) - GPIOT_20 (#466) SDA(26) - GPIOT_21 (#467) | i2cm_a | 0 | /dev/i2c-0 |
Enabel I2C
In order to use the I2C, you need to enable the I2C function via Device Tree Overlay.
VIM1/2/3/3L/Edge1
Edit /boot/env.txt to add the i2c node to overlays node if it doesn't exist.
Take VIM3 as an example to enable I2CM 3, you need to add i2c3 node to overlays node if it doesn't exist.
overlays=uart4 pwm_ao_a pwm_f i2c3
After reboot, you will see the I2C device node.
$ ls /dev/i2c-3
/dev/i2c-3
VIM4
Edit /boot/dtb/amlogic/kvim4.dtb.overlay.env to add i2c node to fdt_overlays node if it doesn't exist.
e.g. Enable I2CM A, you need to add i2cm_a to node fdt_overlays if it doesn't exist.
fdt_overlays=i2cm_a
After reboot, you will see the I2C device node.
$ ls /dev/i2c-0
/dev/i2c-0
Disable I2C to Use GPIO
If you want to use normal GPIO instead of I2C, you can remove the I2C node in device tree overlays configration file.