D435 Trigger output setup

[jasonb]

I'd like to synchronize the depth and RGB streams of the D435 and get an output a pulse at the start of each frame capture (that I can detect with an autopilot or IMU)

I've looked at these posts:

https://forums.intel.com/s/question/0D70P000006FlvvSAC

https://forums.intel.com/s/question/0D50P0000490URESA2/d435-vsync-pin

https://forums.intel.com/s/question/0D50P0000490XgeSAE/how-to-properly-setup-external-triggering-on-d415-and-d435

https://forums.intel.com/s/question/0D50P00004HYmtSSAT/external-triggering-d435-camera

but they don't quite answer what I'm trying to do. I've looked at the multicamera setup white paper as well. I only have one camera so I think all I need to do is set it to enable the output trigger (which I can do for the depth stream from the realsense viewer)

I don't remember where I read it but from what I understand the RGB sensor has to be master. But in the realsense viewer I have (v2.19.1) only the depth stream has an option to enable output trigger. And the trigger will only output if the depth stream is set to master.

Is it possible to sync the RGB and depth stream (using the RGB as master) and output a pulse (pin 5 sync pin)? I haven't tried through librealsense yet only through the realsense viewer.

Thanks

[SMali10]

Only the depth cameras on the D435s can be synced together. The RGB cameras are apparently on a separate chip board from the depth cameras, and it is impossible to get a synchronous capture, or an even an accurate time stamp between RGB cameras, even between the RGB and depth cameras on the same RealSense device.

[Alexandra_C_Intel]

Hi jasonb, Thank you for your interest in the Intel RealSense D435 camera. You may find this helpful: https://github.com/IntelRealSense/librealsense/issues/2637#issuecomment-434033389 Also, as mentioned here https://github.com/IntelRealSense/librealsense/issues/2637, when working with a single camera, hardware sync between color and depth kicks-in once they run at the same actual FPS. To ensure it, you can disable Auto Exposure Priority control under RGB Camera > Controls (this way the camera won't reduce FPS in a dark room to get more light). The way it works is by color sensor sending sync signal to the depth sensor. This is why it is problematic to set it up in multi-camera scenario. Color sensor always wants to be the master. The output sync pulse can be recognized as the VSYNC pulse of the depth sensor. PIN5 is the Sync trigger for both Master (output) and Slave (input). The Master Cam will generate a pulse (50us, 1.8V) on PIN5 every frame, and drive PIN5 on Slave Cams. Let me know if this helps. Regards, Alexandra

[SMali10]

Hi Alexandra,

According to multiple responses from Intel, multiple threads in this forum, and webinars, the RGB and Depth streams of the D435 cameras CANNOT be hardware synced.

https://forums.intel.com/s/question/0D70P0000069CN4SAM

https://forums.intel.com/s/question/0D70P0000068mcISAQ

https://forums.intel.com/s/question/0D50P0000490RYXSA2/hardware-sync-of-color-and-depth-in-d435?language=en_US

https://forums.intel.com/s/question/0D50P00004B5zslSAB/transcript-of-text-faq-questions-from-the-intel-multiple-realsense-cameras-webinar?language=en_US

Can you please confirm whether or not the D435 camera is capable of hardware sync between it's color and depth cameras?

[jasonb]

Ah--that was the post I found earlier and couldn't find again. Thanks. Just to be clear though, in order to get a pulse out of VSYNC pin I have to set the Stereo Module->Controls->Output Trigger Enabled and Stereo Module->Controls->Inter Cam Sync Mode = 1 (i.e. master). There's no pulse on the VSYNC pin with any other settings combination. So it appears that the rgb camera's pulse does not output to the VSYNC pin? Will the two streams sync if both are set to master? (i'm guessing no).

Thanks

Jason

[Alexandra_C_Intel]

Hi jasonb, Can you please tell me what are you trying to accomplish? Regards, Alexandra