SPL Sense for Linux

• 1: Hardware and operating system
• 2: Installation
• 3: Update
• 4: Operation

1 - Hardware and operating system

Hardware

You can buy the Raspberry Pi from electronics retailers. We have tested:

• Raspberry Pi 4 or 5, Model B (all memory variants)
• for power over the network cable: the official Power-over-Ethernet module (PoE HAT) for the Raspberry Pi 3B+ and 4B

Memory card

The memory card is the part most likely to fail after many operating hours. SPL Sense writes little, but a high-quality micro SD card is still worth it. We have had good experiences with “SanDisk Extreme Pro”.

Size is hardly an issue: Raspberry Pi OS with desktop fits on 8 GB, and even a lot of measurement data needs barely a gigabyte. We recommend at least 16 GB.

Installing the operating system

1. Install the Raspberry Pi Imager on your computer (available on the Raspberry Pi website).
2. Use it to write Raspberry Pi OS with Desktop to the memory card.
   • Choose 32 or 64 bit. For a Raspberry Pi 5 we recommend 64 bit. Remember your choice: you need the matching package when installing SPL Sense.
   • In the Imager settings, set a user name and password, and switch on SSH if you want to set up the Raspberry Pi from another computer.

If you are experienced with the command line and don’t need a screen on the Raspberry Pi, Raspberry Pi OS Lite without desktop is enough. This guide assumes the desktop variant.

Assembling

1. Install the Raspberry Pi with the desired add-on modules in the case and insert the memory card.
2. Connect screen, keyboard and mouse.
3. Connect power (or the network cable with PoE). The Raspberry Pi starts.
4. On first start, set up a network connection, by cable or Wi-Fi. SPL Sense is downloaded from the internet in the next step.
5. If not already switched on in the Imager: enable SSH under Raspberry menu › Preferences › Raspberry Pi Configuration › Interfaces.
6. Note the IP address of the Raspberry Pi: it appears when you hover the mouse over the network icon at the top right.

2 - Installation

SPL Sense is installed via the command line, either directly on the Raspberry Pi (program Terminal) or via SSH from another computer. With SSH you can copy and paste the commands and avoid typing errors.

Connecting via SSH

Your computer must be in the same network as the Raspberry Pi.

• macOS and Linux: in the terminal ssh <user>@<ip-address>, for example ssh pi@192.168.10.144
• Windows: in the terminal (PowerShell) also ssh <user>@<ip-address>, or with PuTTY: enter the IP address under Host Name, set Connection type to SSH, then Open

User and password are the ones you set in the Raspberry Pi Imager.

General notes

• Linux is case-sensitive. Copy the commands exactly.
• A successful command usually shows no message. If an error message appears, read it and fix the error before you continue.
• At the first sudo, the Raspberry Pi asks for your user’s password.

1. Create a user for SPL Sense

sudo useradd splsense -m -d /opt/splsense-data

SPL Sense runs under this dedicated user and stores its data in /opt/splsense-data.

2. Download and unpack SPL Sense

For a 32-bit operating system:

wget https://r.spl.swiss/dl/splsense/linux-arm -O splsense-latest.tar.gz
tar xfvz splsense-latest.tar.gz
rm splsense-latest.tar.gz

For a 64-bit operating system:

wget https://r.spl.swiss/dl/splsense/linux-arm64 -O splsense-latest.tar.gz
tar xfvz splsense-latest.tar.gz
rm splsense-latest.tar.gz

3. Move the program to its place

sudo mv splsense /usr/local
sudo chown splsense /usr/local/splsense -R
sudo chgrp splsense /usr/local/splsense -R

4. Set up the service

So that SPL Sense starts automatically at boot, set it up as a system service. Open a new file in the nano editor:

sudo nano /etc/systemd/system/splsense.service

Copy this content into it:

[Unit]
Description=SPL Sense
After=network-online.target
User=splsense
Group=splsense

[Service]
Type=simple
ExecStart=/usr/local/splsense/SplSense.App.Browser
WorkingDirectory=/usr/local/splsense
Environment="ASPNETCORE_URLS=http://0.0.0.0:8080"
Environment="SPLSENSE_DATA=/opt/splsense-data"

[Install]
WantedBy=multi-user.target

Save and close: Ctrl+X, then confirm with Y.

The ASPNETCORE_URLS line defines the address and port at which SPL Sense can be reached: here 8080 on all network interfaces. Enter a different port here if needed. Without this line, SPL Sense can only be reached on the Raspberry Pi itself (http://localhost:5000).

5. Enable and start the service

sudo systemctl enable splsense
sudo service splsense start

6. Restart

sudo reboot

Done

SPL Sense now starts automatically at every boot and runs in the background. In the browser of the Raspberry Pi or of another device in the network, open the IP address with the port, for example http://192.168.10.144:8080.

From here it works as on any other platform, for example with the quick start. For operation as a permanent measuring station, see Operation.

3 - Update

Automatically

On Linux, SPL Sense updates itself like on the other platforms: when a new version is available, Update available appears on the overview. Stop the measurement and click Update and Update and restart. See Installation and updates.

This works if SPL Sense is set up as described in the installation.

Manually

If the automatic update fails, update via the command line. Connect to the Raspberry Pi as in the installation. The general notes apply here too.

1. Stop SPL Sense

sudo service splsense stop

2. Download and unpack the new version

32 bit:

wget https://r.spl.swiss/dl/splsense/linux-arm -O splsense-latest.tar.gz
tar xfvz splsense-latest.tar.gz
rm splsense-latest.tar.gz

64 bit:

wget https://r.spl.swiss/dl/splsense/linux-arm64 -O splsense-latest.tar.gz
tar xfvz splsense-latest.tar.gz
rm splsense-latest.tar.gz

3. Replace the old version

sudo rm -rf /usr/local/splsense
sudo mv splsense /usr/local
sudo chown splsense /usr/local/splsense -R
sudo chgrp splsense /usr/local/splsense -R

The measurement data is in /opt/splsense-data and is kept.

4. Start and restart

sudo service splsense start
sudo reboot

4 - Operation

Addresses

With port 8080 from the installation:

On the Raspberry Pi itself, you can use localhost instead of the IP address.

Kiosk display

For a permanent display, for example a screen at the DJ booth, the browser opens the live screen directly in kiosk mode, for example with Chromium:

chromium-browser --kiosk "http://localhost:8080/measurement/live?kiosk"

Kiosk mode only shows the widgets and a narrow status bar and adapts to the screen size. See Live screen and kiosk.

Unattended permanent measuring station

1. Switch on autonomous mode: the measurement starts by itself after every restart, for example after a power failure.
2. Set an operator PIN: without the PIN, only the live screen is accessible, also in the browser of other devices.
3. Connect to SPL Cloud and switch on the cloud uplink.
4. Optionally with Pro: alarms on failure and remote control.

Limitation

You cannot calibrate the sensor on Linux. For that you need SPL Sense for Windows or macOS.