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--- docs:techref:hardware:port.gpio:1-wire [2019/09/14 00:09] – [Configuration] elux011
+++ docs:techref:hardware:port.gpio:1-wire [2024/09/18 09:35] (current) – [1-wire Bus] elux011
@@ Line 4: / Line 4: @@
 But 1-Wire devices can also be interfaced directly to Controllers from various vendors using a GPIO Pin.
-This guide will only cover 1-Wire Bus Connections because (as of Sep 13, 2019) it is the latest stable release available to Openwrt systems. The Device which got tested was a OrangePI PC+ running OpenWrt v18.06.4.
+This guide will only cover 1-Wire Bus Connections  (as of Sep 13, 2019) up to the stable release v19.07.8. For newer Kernels (since v21.02.0) the Package "kmod-w1-gpio-custom" is no longer available.
+Therefore the Installation is a bit more extensive.
+The Device which got tested was a **OrangePI PC+** (a different method is recommended for the Raspberry Pi!).
-===== Installation =====
+===== Installation up to v19.07.8=====
-In order to use a GPIO for the 1-Wire bus, e.g. for using [[https://datasheets.maximintegrated.com/en/ds/DS18B20.pdf|B18S20 Sensors]] it is necessary to install several additional packages:
+In order to use a GPIO for the 1-Wire bus, i.e. for using [[https://datasheets.maximintegrated.com/en/ds/DS18B20.pdf|DS18B20 Sensors]] it is necessary to install several additional packages:
 <code>
@@ Line 16: / Line 18: @@
-===== Configuration =====
+===== Configuration up to v19.07.8=====
 Configure the GPIO pin connected to the data line of the sensor.
@@ Line 30: / Line 32: @@
 The last Zero of the sequence means "not open-drain" and should be set to "0".
-After modifying the file /etc/modules.d , restart so that the kernel can load the modules.
+After modifying the file /etc/modules.d restart, so that the kernel can load the modules.
 When the 1-Wire bus is successfully set up, you should see in /sys/devices a directory called "w1_bus_master1". A second bus will appear as "w1_bus_master2" and so on.
-Within this directory you will find a number of files including "w1_master_slaves_count" which shows the number of devices connected to the 1-Wire bus, and "w1_master_slaves" which contains a list of the device identifiers.
+Within this directory you will find a number of files including "w1_master_slaves_count" which shows the number of detected devices connected to the 1-Wire bus, and "w1_master_slaves" which contains a list of the device identifiers.
 In case, it is a Sunxi Device and you like to connect e.g. Pin 29 (=PA7) [[https://linux-sunxi.org/GPIO|Sunxi]] says:
@@ Line 41: / Line 43: @@
 so the GPIO for PA7 would be ( 1 - 1) * 32 + 7 = 0 + 7 = 7 (since 'a' is the first letter).
+(Or you take a look with
+<code>
+cat /sys/kernel/debug/pinctrl/1c20800.pinctrl/pins
+</code>
+for the mappings...)
 This results in the following configuration
 <code>
@@ Line 46: / Line 55: @@
 </code>
+===== Installation as of v21.02.0 =====
+There are several possible Ways to install.
+The Way described here assumes, that an Image has been installed on a [[docs:guide-user:installation:installation_methods:sd_card|SD card]].
+**This Description again refers to an Orange Pi PC+, Pin "PA3" is to be used as W1 port conected with DS18B20 Sensors.**
+First install the necessary several additional packages:
+<code>
+opkg update
+opkg install kmod-w1 kmod-w1-master-gpio kmod-w1-slave-therm
+</code>
+As of v21.02.0 the Configuration of the Driver is done via the [[docs:guide-developer:defining-firmware-partitions|Device Tree]].
+On your Computer you need a Device-Tree-Compiler installed. Several Linux Distributions have it available in the Repositys.
+The Device Tree can be changed as follows:
+  * Connect the SD Card to your Computer and look at lsblk or dmesg to identify it. In most Cases, it would be something like /dev/sdX.
+  * Mount and open the "20M" Boot Partition.
+  * there are 3 Files in the Partition: boot.scr, dtb, uImage
+  * Copy the File "dtb" to your Computer
+  * decompile
+<code>
+dtc dtb  -O dts -I dtb -o OPi.dts
+</code>
+  * You get a File named "OPi.dts". Edit the File.
+  * Inside the Section "pinctrl@1c20800" (the selected Pin "PA3" is within this range) you have to insert
+<code>  w1-pins {
+        pins = "PA3";
+        function = "gpio_out";
+        phandle = <0x2f>;
+    	};
+</code>
+ and at the end of the file (**but before the last bracket!**) add:
+<code>
+w1-gpio {
+	compatible = "w1-gpio";
+	label = "w1-gpio";
+	pinctrl-names = "default";
+	pinctrl-0 = <0x2f>;
+	gpios = <0xa 0x0 0x3 0x6>;
+	status = "okay";
+	};
+</code>
+Notice:
+  -  phandle: you have to use a hex number following the highest number of phandle used in the file.
+  -  gpios: the "0xa" ist the phandle of the used pinctrl, the "0x0" is the used Bank (0 = A...), the "0x3" is the hex number of the used Pin inside the bank, the "0x6" ist the Configuration of the Pin.
+  * compile
+<code>
+dtc OPi.dts  -O dtb -I dts -o dtb
+</code>
+  * copy the new "dtb" to the SD Card (overwrite the old "dtb")
+  * Check the output of "dmesg" for (error) messages
+<code>
+...
+kern.info kernel: [    7.610839] Driver for 1-wire Dallas network protocol.
+...
+kern.info kernel: [    7.688174] w1_master_driver w1_bus_master1: Attaching one wire slave 28.0416a43244ff crc be
+...
+</code>
+===== electrical Configuration =====
+To connect 1Wire Devices to a Host it is necessary to connect a Pullup Resistor of 4.7 kOhm between the Bus Line and the 3.3V VCC Line.
+On the Internet, other values are given also, here it works well with 4.7kOhm and six DS18B20 Sensors.
+{{:media:doc:howtos:w1-ds18b20.png?direct}}
+It is also possible to operate the 1-Wire Bus with just the Gnd and Bus Lines, with the Sensors deriving power "parasitically" from the Bus Line. For further information, read the datasheet of the device.
+For longer cables, the use of an insulator such as ADUM1201 is recommended.
-...to be continued...