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--- products:sbc:common:applications:gpio:1wire [2022/06/29 23:02]
127.0.0.1 external edit
+++ products:sbc:common:applications:gpio:1wire [2023/11/07 04:59] (current)
nick old revision restored (2023/11/07 04:42)
@@ Line 1: / Line 1: @@
-# 1Wire
+====== 1-Wire ======
-Common part.
+===== Introduction =====
+This page introduces the usage of 1-Wire bus on [[products:sbc:common:applications:gpio:40pin-header|40-Pin Header]].
-<tabbox VIM1>
+===== 1-Wire Information =====
-VIM1
+You can find the default PIN used for ''1-Wire'' bus from the table below.
+|           ^  PIN  ^  GPIO Name  ^  DT Overlays Node  ^  Device Node          ^
+^  VIM1/2   |  37   |  GPIOH_5    |  onewire           |  /sys/bus/w1/devices  |
+^  VIM3/3L  |  15   |  GPIOH_6    | :::                | :::                   |
+^  VIM4     |  37   |  GPIOT_19   | :::                | :::                   |
+^  VIM1S    |  36   |  GPIOZ_8    | :::                | :::                   |
+^  Edge1    |  30   |  GPIO4_A0   | :::                | :::                   |
+|           |       |             | :::                | :::                   |
-**asdasd**
+===== Enable 1-Wire Bus =====
-<tabbox VIM2>
-VIM2
+In order to use the 1-Wire, you need to enable the ''1-Wire'' function via [[products:sbc:common:configurations:device-tree-overlay|Device Tree Overlay]].
-<tabbox VIM3>
-VIM3
+<tabbox VIM1/2/3/3L/Edge1>
-<tabbox VIM3L>
-VIM3L
+Edit ''/boot/env.txt'' to add the onewire node to ''overlays'' node if it doesn't exist.
-<tabbox VIM4>
-VIM4
+Take VIM3 as an example to enable ''1-Wire'', you need to add ''onewire'' node to ''overlays'' node if it doesn't exist.
+```shell
+overlays=onewire
+```
+<tabbox VIM3 with 5.15 kernel>
+Edit ''/boot/dtb/amlogic/kvim3.dtb.overlay.env'' to add onewire node to ''fdt_overlays'' node if it doesn't exist.
+e.g. To enable onewire, you need to add ''onewire'' to node ''fdt_overlays'' if it doesn't exist.
+```shell
+fdt_overlays=onewire
+```
+<tabbox VIM3L with 5.15 kernel>
+Edit ''/boot/dtb/amlogic/kvim3l.dtb.overlay.env'' to add onewire node to ''fdt_overlays'' node if it doesn't exist.
+e.g. To enable onewire, you need to add ''onewire'' to node ''fdt_overlays'' if it doesn't exist.
+```shell
+fdt_overlays=onewire
+```
+<tabbox VIM4>
+Edit ''/boot/dtb/amlogic/kvim4.dtb.overlay.env'' to add onewire node to ''fdt_overlays'' node if it doesn't exist.
+e.g. To enable onewire, you need to add ''onewire'' to node ''fdt_overlays'' if it doesn't exist.
+```shell
+fdt_overlays=onewire
+```
+<tabbox VIM1S>
+Edit ''/boot/dtb/amlogic/kvim1s.dtb.overlay.env'' to add onewire node to ''fdt_overlays'' node if it doesn't exist.
+e.g. To enable onewire, you need to add ''onewire'' to node ''fdt_overlays'' if it doesn't exist.
+```shell
+fdt_overlays=onewire
+```
 </tabbox>
+<WRAP tip >
+Reboot the system for this change to take effect.
+</WRAP>
+===== Get Sensor Data =====
+Here we attach a 1-Wire device ''DS18B20'' temperature sensor to the 1-Wire bus.
+Enter the driver directory:
+```shell
+khadas@Khadas:~$ cd /sys/bus/w1/devices
+khadas@Khadas:/sys/bus/w1/devices$ ls
+-0119395ebf91  w1_bus_master1
+```
+You can see the node of ''ds18b20'' is ''28-0119395ebf91''. Enter this directory:
+```shell
+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:
+```shell
+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
+```
+===== Disable 1-Wire to Use GPIO =====
+If you want to use normal GPIO instead of 1-Wire, you can remove the 1-Wire node in [[products:sbc:common:configurations:device-tree-overlay|Device Tree Overlay]].

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