RealSense Synchronization

This article provides a method to complete a synchronization test on the RealSense Depth Camera D457 through the GMSL link. 

For information on installing the newest RealSense SDK release and updating camera firmware, please see our article, Getting Started with the Latest RealSense SDK.

Documentation on D457 Hardware Synchronization from RealSense can be found here: https://realsenseai.com/wp-content/uploads/2025/08/RealSense-D457-Hardware-Synchronization-V0.11.pdf 

First, in the Linux terminal, run the following commands: 

sudo su
 cd /sys/class/pwm/pwmchip3
 echo 0 > export
 cd pwm0
 echo 33333333 > period
 echo 1000000 > duty_cycle
 echo 1 > enable

This sets the external trigger to 30FPS on the device before streaming. If you would like to achieve a custom trigger rate, you will need to alter the values to meet your requirements.

Next, in the RealSense Viewer SDK, set Inter Cam Sync Mode to "3". To do this, add all camera sources being used in the synchronization to the viewer platform. Within each camera, expand Stereo Module, expand Controls, and locate Inter Cam Sync Mode. Select the edit button and enter a value of 3.

Once Inter Cam Sync Mode has been set to 3 for all cameras, set Frame Rate (FPS) to "30" for all cameras in both the Depth and RGB Module. This will match the external trigger set earlier. If using a custom trigger rate, set all cameras to the appropriate value to achieve your desired Frame Rate. 

You should now be ready to start streaming from the Depth camera and/or RGB camera.

If you would like to reset the frame count to zero for all cameras for your test, open a new terminal and run the following commands:

cd /sys/class/pwm/pwmchip3/pwm0
 echo 0 > enable
 echo 1 > enable

In doing this you should see a log info message within the RealSense Viewer SDK similar to the image below and all Frame Counters should be reset to 0. Note the number of instances of this message should match the number of cameras streaming.