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Table of Contents
I2C
Introduction
This document mainly introduces how to use I2C bus on Khadas SBC. You will learn how to connect I2C devices, check I2C devices, and read device register values.
Hardware Connection
VIM1/2
I2C A
Sensor SCL ↔ I2C_SCK_A (PIN 22)
Sensor SDA ↔ I2C_SDA_A (PIN 23)
Sensor GND ↔ GND
Sensor VCC ↔ 5V or 3.3V //depends on your sensor
I2C B
Sensor SCL ↔ I2C_SCK_B (PIN 25)
Sensor SDA ↔ I2C_SDA_B (PIN 26)
Sensor GND ↔ GND
Sensor VCC ↔ 5V or 3.3V //depends on your sensor
VIM3/3L
I2C 3
Sensor SCL ↔ I2C0_SCK (PIN 22)
Sensor SDA ↔ I2C0_SDA (PIN 23)
Sensor GND ↔ GND
Sensor VCC ↔ 5V or 3.3V //depends on your sensor
I2C 4
Sensor SCL ↔ I2C1_SCK (PIN 25)
Sensor SDA ↔ I2C1_SDA (PIN 26)
Sensor GND ↔ GND
Sensor VCC ↔ 5V or 3.3V //depends on your sensor
VIM4
I2CM A
Sensor SCL ↔ I2CM_A_SCL (PIN 25)
Sensor SDA ↔ I2CM_A_SDA (PIN 26)
Sensor GND ↔ GND
Sensor VCC ↔ 5V or 3.3V //depends on your sensor
I2CM F
Sensor SCL ↔ I2CM_F_SCL (PIN 22)
Sensor SDA ↔ I2CM_F_SDA (PIN 23)
Sensor GND ↔ GND
Sensor VCC ↔ 5V or 3.3V //depends on your sensor
| I2C | PIN & GPIO Number | DT Overlays Node | Bus Number | Device Node |
|---|---|---|---|---|
| I2CM A | SCL - PIN25 - GPIOT_20 (#466) SDA - PIN26 - GPIOT_21 (#467) | i2cm_a | 0 | /dev/i2c-0 |
| I2CM F | SCL - PIN22 - GPIOY_17 (#501) SDA - PIN23 - GPIOY_18 (#502) | i2cm_f | 5 | /dev/i2c-5 |
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.
Take VIM3 as an example to enable i2c3:
overlays=uart4 pwm_ao_a pwm_f i2c3
After reboot, you will see the I2C device node.
khadas@Khadas:~$ ls /dev/i2c-3
/dev/i2c-3
VIM4
Edit /boot/dtb/amlogic/kvim4.dtb.overlay.env to add i2c node to fdt_overlays node.
e.g. Enable I2CM A, you need to add i2cm_a to node fdt_overlays.
fdt_overlays=i2cm_a
After reboot, you will see the I2C device node.
khadas@Khadas:~$ 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.