Table of Contents
1wire bus
The 1wire bus supports various low speed digital devices and is supported in Linux on the Raspberry Pi.
Raspberry Pi
Edit boot/config.txt to assign gpio4 for 1wire.
dtoverlay=w1-gpio,gpiopin=4
Reboot and after load driver.
modprobe w1_gpio
These are the GPIO header pin assignments for the 1 wire bus.
| Pin | Name | Function |
|---|---|---|
| 1 | 3V3 | POWER |
| 6 | GND | GROUND |
| 7 | GPIO4 | DATA |
The relevant pins on the Pi header are as follows.
+---P1---+
3V3 01 02 5V
GPIO0/GPIO2 03 A/A+ 04 5V
GPIO1/GPIO3 05 B/B+ 06 GND
GPIO4 07 2 08 GPIO14/TX
.. ..
NB. The 1 wire data line must pulled high via 4K7 to 3V3 power.
DS18B20 Thermometer
+-------+ | 1 2 3 | +-------+ | | | | | | 1 GROUND 2 DATA 3 POWER
modprobe w1_therm cat /sys/bus/w1/devices/28-041460bdd6ff/w1_slave 8f 01 55 00 7f ff 0c 10 a0 : crc=a0 YES 8f 01 55 00 7f ff 0c 10 a0 t=24937
KEYES KY-001 DS18B20 module
This module re-orders the pins so beware.
+-------+ |DS18B20| | | +-G R Y-+ | | | G GROUND R POWER Y DATA
DATA is pulled up via a 4K7 resistor and an LED. The LED will flash during communication with the chip.
DS2431 EEPROM
+-------+ | 1 2 3 | +-------+ | | | | | | 1 GROUND 2 DATA 3 NC
modprobe w1_ds2431 echo "hello world" > /sys/bus/w1/devices/2d-00000de5d608/eeprom cat /sys/bus/w1/devices/2d-00000de5d608/eeprom hello world