Raspberry Pi

Mar

2023

Systemd service to use a DS3231 RTC on the Raspberry Pi

The following systemd service will automatically. See this guide for more information on the setup and ensure sudo i2cdetect -y 1 detects the RTC with address 0x68.

This is an automatic service installation & enable script based on A simple systemd service autoinstall script . This script will automatically enable the service on boot:

#!/bin/bash
# This script installs and enables/starts a systemd service
# It also installs the service file
export NAME=ConfigureRTC

cat >/etc/systemd/system/${NAME}.service <<EOF
[Unit]
Description=${NAME}

[Service]
ExecStart=/bin/bash -c 'echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device && hwclock -s'
Restart=always

[Install]
WantedBy=multi-user.target
EOF

# Enable and start service
systemctl enable --now ${NAME}.service

This is just the systemd service:

[Unit]
Description=ConfigureRTC

[Service]
ExecStart=/bin/bash -c 'echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device && hwclock -s'
Restart=always

[Install]
WantedBy=multi-user.target

Mar

2023

How to enable or disable NTP time synchronization on the Raspberry Pi

Disable NTP:

sudo systemctl disable --now systemd-timesyncd

Enable NTP:

sudo systemctl enable --now systemd-timesyncd

Verifying if NTP is active

You can verify if NTP is active or not by running

timedatectl

Then look for these lines:

System clock synchronized: yes
NTP service: active

System clock synchronized will tell you if the NTP service has successfully synchronized the system time to a NTP time server: yes if synchronized, no if not synchronized.

NTP service will tell you if the NTP service is running, i.e. if it is trying to synchronize the system time to a NTP time server: active if running, inactive when not running

Output with NTP active:

               Local time: Tue 2023-03-14 16:49:28 CET
           Universal time: Tue 2023-03-14 15:49:28 UTC
                 RTC time: Tue 2023-03-14 15:49:28
                Time zone: Europe/Berlin (CET, +0100)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no

Output with NTP inactive:

               Local time: Tue 2023-03-14 16:48:01 CET
           Universal time: Tue 2023-03-14 15:48:01 UTC
                 RTC time: Tue 2023-03-14 15:48:01
                Time zone: Europe/Berlin (CET, +0100)
System clock synchronized: no
              NTP service: inactive
          RTC in local TZ: no

Mar

2023

How to enable I2C port on the Raspberry Pi using raspi-config

sudo raspi-config nonint do_i2c 0

Now load the relevant modules:

sudo modprobe "i2c-bcm2835"
sudo modprobe "i2c-dev"
sudo modprobe "rtc-ds1307"

and now check if the I2C device file exists using stat /dev/i2c-1:

$ stat /dev/i2c-1
  File: /dev/i2c-1
  Size: 0               Blocks: 0          IO Block: 4096   character special file
Device: 5h/5d   Inode: 169         Links: 1     Device type: 59,1
Access: (0660/crw-rw----)  Uid: (    0/    root)   Gid: (  998/     i2c)
Access: 2023-03-14 16:23:06.643999999 +0100
Modify: 2023-03-14 16:23:06.643999999 +0100
Change: 2023-03-14 16:23:06.643999999 +0100
 Birth: -

If you instead see

ls: cannot access '/dev/i2c-1': No such file or directory

either the driver is not loaded properly or I2C is disabled. Try rebooting the system and repeating the commands above and possibly checking dmesg for any error messages.

Mar

2023

How to fix Raspberry Pi i2cdetect: command not found

Problem:

When trying to detect I2C devices on the Raspberry Pi (Raspbian) using i2cdetect, you see the following error:

$ i2cdetect
bash: i2cdetect: command not found

Solution:

Install i2c-tools using

sudo apt -y install i2c-tools

After installing i2c-tools , you can use i2cdetect and other related tools such as i2cget.

Jan

2023

VirtualHere USB server & systemd autostart on Raspberry Pi in 15 seconds

The following script will download the VirtualHere USB server for the Raspberry Pi (generic version for ARM) and create a systemd service called vhusbd.service.

In case you are not using the Raspberry Pi, see the VirtualHere server download page to obtain.

#!/bin/bash
# This script installs and enables/starts the VirtualHere USB server
wget -O /usr/bin/vhusbd https://www.virtualhere.com/sites/default/files/usbserver/vhusbdarm
chmod a+x /usr/bin/vhusbd

cat >/etc/systemd/system/vhusbd.service <<EOF
[Unit]
Description=vhusbd
After=network-online.target

[Service]
Restart=always
User=root
Group=root
ExecStart=/usr/bin/vhusbd

[Install]
WantedBy=multi-user.target
EOF

# Enable and start service
systemctl enable --now vhusbd.service

Dec

2022

How to take a remote screenshot on the Raspberry Pi

You can login to your Raspi using ssh -CX [email protected] and then run

DISPLAY=:0 scrot screenshot.png

to take a screenshot of the display that is currently attached. After that, use

feh screenshot.png

(due to ssh -CX this will display the image locally on your Linux desktop) or copyscreenshot.png to your local computer using scp, rsync, WinSCP or any other tool.

This is useful for debugging what is happening on your display.

Dec

2022

Raspberry Pi libcamera VLC recording to H.264 (1920×1080)

On the Pi, run

libcamera-vid -t 0 --width 1920 --height 1080 --codec h264 -o out.h264

This will record Full-HD video (1920×1080) to out.h264

Dec

2022

How to list available cameras on Raspberry Pi (libcamera)

Use this command to list all available cameras:

libcamera-still --list-cameras

Example output:

$ libcamera-still --list-cameras
Available cameras
-----------------
0 : imx477 [4056x3040] (/base/soc/i2c0mux/[email protected]/[email protected])
    Modes: 'SRGGB10_CSI2P' : 1332x990 [120.05 fps - (696, 528)/2664x1980 crop]
           'SRGGB12_CSI2P' : 2028x1080 [50.03 fps - (0, 440)/4056x2160 crop]
                             2028x1520 [40.01 fps - (0, 0)/4056x3040 crop]
                             4056x3040 [10.00 fps - (0, 0)/4056x3040 crop]

Dec

2022

How to fix Raspberry Pi OS raspivid: command not found

Problem:

When trying to run raspivid on Raspberry Pi OS Lite, you will see the following error message:

bash: raspivid: command not found

Solution:

In recent versions of Raspberry Pi OS, raspivid has been replaced by libcamera-vid. Therefore, use libcamera-vid instead of raspivid.

Dec

2022

How to allow remote SMB/CIFS access to /home/pi on the Raspberry Pi

First, install samba using

sudo apt -y install samba

then append the following to /etc/samba/smb.conf

[pi]
   comment = pi
   path = /home/pi
   writeable = yes
   browseable = yes
   public = yes
   create mask = 0644
   directory mask = 0755
   force user = pi

and finally restart samba:

sudo systemctl restart smbd

Now your /home/pi will be accessible via SMB (including write access).

Dec

2022

How to setup image slideshow kiosk on Raspbian

1. Configure autologin

sudo raspi-config -> 1 System options -> S5 Boot / auto-login -> Set to B2 Console Autologin

2. Use our script to configure the kiosk

sudo apt -y install xserver-xorg xinit x11-xserver-utils matchbox-window-manager xautomation unclutter feh
mkdir -p ~/kiosk-images

sudo cat >~/kiosk.sh <<EOF
#!/bin/sh
xset -dpms
xset s off
xset s noblank
matchbox-window-manager -use_titlebar no &
unclutter &
feh -Y -x -q -D 5 -B black -F -Z -z -r ~/kiosk-images
EOF
chmod a+x ~/kiosk.sh

sudo cat >>~/.bashrc <<EOF
# Kiosk xinit
xinit ~/kiosk.sh -- vt$(fgconsole)
EOF

3. Place images in `~/kiosk-images`

e.g. via scp or rsync

4. Reboot

sudo reboot

Note: When logging in using SSH, the .bashrc hack (found originally at reelyactive) will cause xinit to run, with the message

/usr/lib/xorg/Xorg.wrap: Only console users are allowed to run the X server

appearing on screen and the console not opening. In that case, just type Ctrl+C to stop xinit and see the normal shell.

Apr

2022

How to enable USB-C host mode on Raspberry Pi

If you want to connect an USB device such as a 3D printer mainboard to your Raspberry Pi 4 using the USB-C connector as opposed to the larger USB-A connector, you need to first configure the Raspberry Pi kernel to use host mode for the USB-C connector.

To temporarily enable it:

sudo modprobe -r dwc2 && sudo dtoverlay dwc2 dr_mode=host && sudo modprobe dwc2

This method has the advantage of not requiring a reboot.

To permanently enable it:

Edit /boot/config.txt and add

dtoverlay=dwc2,dr_mode=host

at the end of the file (in the [all] section). Then

reboot

Mar

2022

How to install tailscale on Ubuntu

In order to instal tailscale, on any Ubuntu version, you can use the official tailscale install command:

sudo apt -y install curl apt-transport-https
curl -fsSL https://tailscale.com/install.sh | sh

Mar

2022

Fullscreen camera view using libcamera-vid

libcamera-vid --width 1920 --height 1080 -f -t 10000000000

-t 10000000000 means to run for 10000000000 milliseconds (almost 4 months)

Mar

2022

How to fix raspistill ERROR: the system should be configured for the legacy camera stack

Problem:

While trying to capture an image using raspistill, you see the following error message

ERROR: the system should be configured for the legacy camera stack

and no image is being produced

Solution 1 (recommended): Use `libcamera`

Recent versions of Raspbian use libcamera instead of the broadcom legacy camera API. You can capture an image using libcamera-still similarly to raspistill:

libcamera-still -o test.jpg

Solution 2: Enable legacy camera API

If you absolutely need raspistill specifically to work, you can still enable the legacy camera API using rpi-config:

sudo raspi-config

Go to:

3 Interface Config
I1 Legacy Camera

and choose Yes to enable the legacy camera API.

Mar

2022

Raspberry Pi libcamera VLC livestreaming (1920×1080)

On the Pi, run

libcamera-vid -t 0 --width 1920 --height 1080 --codec h264 --inline --listen -o tcp://0.0.0.0:8888

On the client, run

vlc tcp/h264://192.168.1.185:8888/

where 192.168.1.185 is the IP address of the Raspberry Pi.

Feb

2022

What pin pitch does the Raspberry Pi DSI display connector / cable have?

The Raspberry Pi DSI display connector (for example the DSI display cable that comes with the Raspberry Pi 7″ display) has a pin pitch of 1.0mm:

Feb

2022

How to install tailscale on Raspberry Pi

Just use the official install command from the tailscale website:

curl -fsSL https://tailscale.com/install.sh | sh

Feb

2022

Which way to mount the Raspberry Pi DSI display cable for the Raspberry Pi 7″ display

First, mount the Raspberry Pi on top of the display PCB on the back of the display.

On the bottom (display) PCB, the silver contacts of the cable should be at the top (facing the Raspberry Pi):

On the Raspberry Pi, the silver contacts should face towards the USB connectors:

Overall, it should look like this:

Feb

2022

How to enable OctoPi WiFi connection on boot

First, install OctoPi to the SD card – for example, using rpi-imager: How to install OctoPi using rpi-imager

Open the boot partition on the OctoPi SD card and create a file wpa_supplicant.conf there, with the following content:

country=de
update_config=1
ctrl_interface=/var/run/wpa_supplicant

network={   
   scan_ssid=1
   ssid="MyWifi"  
   psk="abc123abc"
}

Always set the correct country code at the top ! If you don’t set it correctly, it won’t work!

Set ssid to the name of the wireless network.

Set psk to the wifi password.

Disable NTP:

Enable NTP:

Verifying if NTP is active

Output with NTP active:

Output with NTP inactive:

Problem:

Solution:

Example output:

Problem:

Solution:

1. Configure autologin

2. Use our script to configure the kiosk

3. Place images in ~/kiosk-images

4. Reboot

To temporarily enable it:

To permanently enable it:

Problem:

Solution 1 (recommended): Use libcamera

Solution 2: Enable legacy camera API

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3. Place images in `~/kiosk-images`

Solution 1 (recommended): Use `libcamera`