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IntelRealSense
Low voltages when trying to hardware sync multiple D455 cameras
| Required Info | |
|---|---|
| Camera Model | D455 } |
| Firmware Version | 5.16.0.1 |
| Operating System & Version | Ubuntu 20.04 |
| Kernel Version (Linux Only) | 5.10.192-tegra |
| Platform | NVIDIA Jetson Orin Dev Kit 64GB |
| SDK Version | 2.55.1 |
| Language | python |
| Segment | Robotics |
Issue Description
Hi there, I am trying to set up Hardware Sync between 2 Intel RealSense D455 cameras. I am using Python to configure and start the cameras. According to the "Multi camera configurations" whitepaper (https://dev.intelrealsense.com/docs/multiple-depth-cameras-configuration) Pins 5 (Signal) and Pins 9 (Ground) of both cameras need to be connected. In the python file I then used the following code to set on of my cameras to "Master":
device_right.first_depth_sensor().set_option(rs.option.inter_cam_sync_mode, 1) # Master device_left.first_depth_sensor().set_option(rs.option.inter_cam_sync_mode, 2) # Slave
Here's the problem: When checking the signals sent between the two cameras on Pins 9 and 5, i get the correct frequency of about 30Hz (camera configured to 30fps), but the Peak-to-Peak Voltage is only about 100mV. From what I've read, a Peak-to-Peak Voltage of 1.8V is needed for the "slave"-camera to recognize the trigger signal. I have measured the Voltage directly at the Pins, so faulty connections are not the problem.
Has anyone experienced a similar issue before. I hope someone can help me with known explanations / solutions for my problem.
Thanks
Hi @Nico-Sander Are you measuring for 1.8 V on Pin 5 of the Master camera whilst the Master camera is active, please? A Master camera generates a sync pulse on Pin 5 (the sync pin) when its Inter Cam Sync Mode is set to 1. The camera would have to be actively depth-streaming in order for the trigger pulse to be generated.
Hello Marty, yes the Master camera is actively streaming. I am visualizing the depth and color output while measuring the sync signals. I like to add, that i get the same voltage readings when starting the camera with realsense-viewer. So the Inter Sync Mode seems to be set correctly.
The value of 1.8 v is always referred to in regard to use of an external trigger signal. It is never referred to in regard to triggering by a master camera.
A known characteristic of a trigger generated by a master camera is that it should have a pulse width of 50 microseconds, whilst an external trigger should have a pulse width of 100 microseconds or more.
Hi Marty, thanks for the explanation. I will try to measure the pulse width tomorrow and will get back to you.
Quick follow up on my issue. The problem is resolved and the sync seems to be working. I tried to measure the pulse-width today and was able to see the 50us pulse-width generated by the master camera.
You can also see that the voltage is now 1.74V, maybe a restart of my system was all that was necessary to get a better voltage.
I validated that the sync is working, by placing a millisecond clock in the overlapping field of view of the 2 cameras. Both cameras always show the exact same state of the clock, so the cameras capture the images within the same millisecond.
That's great news that your setup is working correctly. Thanks very much for the update!
Hi @Nico-Sander Do you require further assistance with this case, please? Thanks!
Hi @MartyG-RealSense, thanks again for answering all my questions. Everything works fine now. Feel free to close this Issue.
You are very welcome, @Nico-Sander - I'm pleased to hear that it is working well. As you suggested, I will close the issue. Thanks again!