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products:sbc:common:applications:gpio:1wire
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Table of Contents
1-Wire
Introduction
This document mainly introduces the usage of 1-Wire bus on 40-Pin Header.
1-Wire 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 |
Enable 1-Wire Bus
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.
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
Last modified: 2022/07/12 23:20 by nick