I recently bought a Raspberry Pi 4 and for one my projects, I wanted to make an OLED display work with the Pi. In this post, I will show you how I was able to achieve it.
This post is inspired from the guide of Michael Clements on how to add an OLED Display with Raspberry Pi OS Bullseye. It is worth taking a look.
What you need
- Raspberry Pi 4
- Ubuntu Server 21.10 (I use the 64-bit version)
- An 128×64 I2C OLED display
Installation
I will assume that you’ve manage to install the 64-bit version of Ubuntu Server 21.10 on the Pi
The first thing you will need to do is to make sure that you OS is up to date
sudo apt update && sudo apt upgrade -yOnce the system has been update, reboot you Pi.
sudo rebootThe next step will be to install the necessary drivers and libraries to
sudo apt install -y python3-pip python3-dev python3-pil python3-setuptools python3-rpi.gpio i2c-toolsAdd your current user account to the group i2c
sudo usermod -aG i2c ubuntuConnect the OLED Display to the Raspberry Pi. For this part, I will again recommend to visit this post. Once the display is connected, check if it is properly recognized by the system.
i2cdetect -y 1The output should look like the following:
ubuntu@ubuntu:~$ i2cdetect -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- 3c -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
ubuntu@ubuntu:~$Install SSD1306 python libary.
sudo pip3 install adafruit-circuitpython-ssd1306Now I originally wanted to have a display to show information about my system. Therefore for the sake of this post, we will reuse the script of Michael Klements.
git clone https://github.com/mklements/OLED_Stats.gitGo to the cloned directory
cd OLED_StatsThen run the script by entering:
python3 stats.pyIf you have the following error when you execute the script:
ubuntu@ubuntu:~/OLED_Stats$ python3 stats.py
Traceback (most recent call last):
File "/home/ubuntu/OLED_Stats/stats.py", line 16, in <module>
oled_reset = digitalio.DigitalInOut(board.D4)
File "/usr/local/lib/python3.9/dist-packages/digitalio.py", line 145, in __init__
self.direction = Direction.INPUT
File "/usr/local/lib/python3.9/dist-packages/digitalio.py", line 175, in direction
self._pin.init(mode=Pin.IN)
File "/usr/local/lib/python3.9/dist-packages/adafruit_blinka/microcontroller/bcm283x/pin.py", line 37, in init
GPIO.setup(self.id, GPIO.IN)
RuntimeError: Not running on a RPi!
ubuntu@ubuntu:~/OLED_Stats$Pay attention to the last line! It means that you have a persmission problem. There are two methods to solve this issue:
Method 1. Run the script with elevated privileges:
sudo python3 stats.pyMethod 2. Make sure the current user has the proper privileges.
With Ubuntu server 21.10 64-bit on RPi 4, that can be achieved by creating a gpio group, and adding an udev rule to give this group access to /dev/gpiomem (which can normally only be accessed by root).
Create a /etc/udev/rules.d/90-gpio.rules file
sudoedit /etc/udev/rules.d/90-gpio.rulesadd the following content
KERNEL=="gpiomem", OWNER="root", GROUP="gpio"Create the group gpio and assign it to an existing user, in my case “ubuntu”:
sudo groupadd -f --system gpio
sudo usermod -a -G gpio ubuntuReboot the machine.
sudo rebootYou should now be able to run the script as following:
python3 stats.pyRun the script on system start up
If you want to run the display command script every time you start the system, do the following:
Open up crontab by entering the following command
crontab –eAdd the following line to the end of the file to run the script
@reboot cd /home/ubuntu/OLED_Stats && python3 stats.py &Now reboot the Pi. Yyou should now have a working OLED stats display that starts up automatically each time your Pi boots up.