Banana Pi: Temperature Sensor (DS18B20) - Tutorial

Requirements

--> Banana Pi running Raspbian for Banana Pi
--> Breadboard
--> Jumper Wires
--> DS18b20
--> 4.7K Ohm resistor
--> Breakout cobbler

 

Hardware Setup

Refer to the graphic for the correct wiring. Make sure the Banana Pi is switched off to prevent any possible damage.

Software Setup

Double check the wiring and boot the device. In order to be able to access the temperature data, we need to make some minor adjustments to the script.bin file, which is a binary configuration file used by Allwinner SOC.

sudo apt-get install git
git clone https://github.com/linux-sunxi/sunxi-tools
cd sunxi-tools
make

#location of the script.bin file
cd /boot/bananapi/

#get the fex file
sudo /home/bananapi/sunxi-tools/bin2fex script.bin bananapi.fex

#edit the fex file
sudo nano bananapi.fex

#add the following at the end, save (CTRL + O) and close
[w1_para]
gpio = 4

#.fex back to .bin
sudo /home/bananapi/sunxi-tools/fex2bin bananapi.fex script.bin

sudo reboot

Reading raw data from the sensor

After successfully rebooting your device, you will notice that /sys/bus/w1/devices is no longer empty.

bananapi@lemaker ~ $ cd /sys/bus/w1/devices
bananapi@lemaker /sys/bus/w1/devices $ ls
28-000006203041  w1_bus_master1
bananapi@lemaker /sys/bus/w1/devices $ cd 28-000006203041
bananapi@lemaker /sys/bus/w1/devices/28-000006203041 $ ls
driver  id  name  power  subsystem  uevent  w1_slave
bananapi@lemaker /sys/bus/w1/devices/28-000006203041 $ cat w1_slave
5e 01 4b 46 7f ff 02 10 8d : crc=8d YES
5e 01 4b 46 7f ff 02 10 8d t=21875

t=21875 is the number we are looking for. E.g.: 21.9 degree Celsius (°C) in my case.

my setup