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Table of Contents
1-Wire
Introduction
This document will explain how to use 1-Wire bus on Khadas SBC. You will learn how to turn it on and how to get sensor data through 1-Wire bus.
Enable 1-Wire
You can enable 1-Wire bus via device tree overlay.
VIM1/2/3/3L/Edge1
Edit /boot/env.txt to add onewire to overlays node.
e.g.
overlays=uart4 pwm_ao_a pwm_f i2c0 onewire
VIM4
Edit /boot/dtb/amlogic/kvim4.dtb.overlay.env to add onewire to fdt_overlays node.
e.g.
fdt_overlays=onewire
Reboot to effect.
For more information, please check Device Tree Overlay.
Get Sensor Data
Here we attach a 1-Wire device DS18B20 temperature sensor to the 1-Wire bus.
Enter the driver directory:
khadas@Khadas:~$ cd /sys/bus/w1/devices khadas@Khadas:/sys/bus/w1/devices$ ls 28-0119395ebf91 w1_bus_master1
You can see the node of ds18b20 is 28-0119395ebf91. Enter this directory:
khadas@Khadas:/sys/bus/w1/devices$ cd 28-0119395ebf91 khadas@Khadas:/sys/bus/w1/devices/28-0119395ebf91$ ls driver id name power subsystem uevent w1_slave
Read w1_slave file will get the temperature value:
khadas@Khadas:/sys/bus/w1/devices/28-0119395ebf91$ cat w1_slave
b1 01 4b 46 7f ff 0c 10 d8 : crc=d8 YES
b1 01 4b 46 7f ff 0c 10 d8 t=27062
Physical pins of 1-Wire bus:
VIM1/2
GPIOH_5 - PIN37
VIM3/3L
GPIOH_6 - PIN15
VIM4
GPIOT_19 - PIN37
Edge1
GPIO4_A0 - PIN30