Using GMSL with ZED Box 2

The ZED Box 2 comes with two embedded GMSL2 quad deserializers, so you can connect up to 8 ZED X and ZED X One cameras, or any other supported GMSL2 camera.

GMSL driver

The ZED X cameras require a GMSL driver. It comes already installed with the ZED Box 2.

You may need to install it manually, especially if you upgraded your system version. Go to our website and download the ZED Box 2 driver version that matches your L4T version.

To find your Jetson Linux (L4T) version, run:

cat /etc/nv_tegra_release

You will obtain an output like this:

# R36 (release), REVISION: 4.3, GCID: ..., BOARD: generic, EABI: aarch64, DATE: ...

In this example, the L4T version is 36.4.3.

Then, open a terminal in the folder that contains the downloaded driver and run:

sudo dpkg -i <the deb file path>

Finally, reboot the device.

Multi-camera configurations

The ZED Box 2 provides 8 GMSL2 ports on two Quad FAKRA-Z connectors. Each connector is driven by its own deserializer:

• Connector #1: ports 1 to 4
• Connector #2: ports 5 to 8

On each connector, the ports are organized in two pairs of adjacent ports: ports 1-2 and 3-4 on connector #1, ports 5-6 and 7-8 on connector #2.

The bandwidth is shared between the cameras connected to the same Quad FAKRA-Z connector. Please refer to the table below to understand how different camera configurations provide different image capture behaviors, according to the number of cameras, their type, and the ports they are connected to:

Beyond the GMSL2 bandwidth, the number of cameras you can process in real time also depends on the ZED SDK modules you run and on the power mode of the Jetson module. Read Frame rate and latency to size your application.

Camera synchronization

The cameras connected to the same Quad FAKRA-Z connector are natively synchronized by their deserializer. The synchronization of the two deserializers, and of several ZED Box 2 units, is configured with the sync_mode parameter of the ZED X daemon, in the file /etc/systemd/system/zed_x_daemon.service:

Change the mode with the following commands, replacing <mode> with 0, 1, or 2:

sudo sed -i 's/^sync_mode=./sync_mode=<mode>/' /etc/systemd/system/zed_x_daemon.service
sudo systemctl daemon-reload
sudo systemctl restart zed_x_daemon.service

The mode is kept across reboots.

Synchronize all the cameras of a ZED Box 2

To synchronize the cameras connected to the two Quad FAKRA-Z connectors together, for example for 360° perception with 8 cameras, set sync_mode=1:

sudo sed -i 's/^sync_mode=./sync_mode=1/' /etc/systemd/system/zed_x_daemon.service
sudo systemctl daemon-reload
sudo systemctl restart zed_x_daemon.service

Now, all the cameras connected to the ZED Box 2 have synchronized frame acquisition with 15µs precision.

Multi-device synchronization

Several ZED Box 2 units can share the same frame-sync trigger, so that the grab calls of the ZED SDK on all the devices are aligned on the same clock signal.

The devices are wired in a star configuration: the trigger output of the Master is split to reach the trigger input of each Slave. Unlike the ZED Box Mini, the ZED Box 2 units are not daisy-chained: a Slave does not forward the trigger signal to another Slave.

1. Designate one ZED Box 2 as Master and set sync_mode=1 on it, as described above.

2. On each Slave ZED Box 2, set sync_mode=2:

   sudo sed -i 's/^sync_mode=./sync_mode=2/' /etc/systemd/system/zed_x_daemon.service
   sudo systemctl daemon-reload

3. Connect a GND pin (for example pin #5) of the Master to a GND pin of each Slave.

4. Split the wire from pin #1 (DESER_1_TRIGOUT) of the Master, and connect it to pin #2 (DESER_2_TRIGIN) of each Slave.

5. Restart the ZED X daemon on each Slave:

   sudo systemctl restart zed_x_daemon.service

6. Verify the Slave configuration:

   sudo dmesg | grep Sync

   The output should report Sync mode configured for the deserializers.

When you use an external trigger source instead of a Master ZED Box 2, it must provide a signal with the following characteristics:

• Square wave
• Amplitude: 1.8V, never higher
• Frequency: the camera frame rate set in the ZED SDK (15Hz, 30Hz, 60Hz, or 120Hz)

Developing your own driver

If you intend to use a GMSL device alongside a StereoLabs ZED X camera, a custom driver is required for compatibility.

In such cases, we recommend reaching out to our support team at support@stereolabs.com for more information and assistance.