Time sync across cameras + triggering other sensors e.g. lidar

Autonomous Vehicles DRIVE AGX Xavier DRIVE AGX Xavier General
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GMSL2 cameras are sync’d. Timestamps across frames are all matching, which verifies that frame grabs across all cameras are triggered off the same clock signal.

Any tips on how to synchronise other sensors e.g. lidar, radar, imu, gnss? So if a sensor has a trigger pin, how to get the sensor to be triggered at the same time as the cameras?

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Dear @sleff,
Could you check How to synchronize camera with lidar? if it helps.

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Thanks @SivaRamaKrishnaNV for the link. It helps to know that dwLidarDecodedPacket has separate timestamps for host and sensor, i.e. hostTimestamp and sensorTimestamp.

Can you help further with any tips on triggering sensors? For example, one of my sensors has a GPIO pin to trigger a detection, which I want to be able to trigger at the same clock sync as cameras. Is there a hardware pin out on the Drive that is sync’d to the cameras?

5

Dear @sleff ,
SoC generates a PWM signal on a GPIO pin that is connected to all deserializers. This common PWM signal is then forwarded to all 16 GMSL cameras to achieve frame synchronization.

Are you asking how to you want to use the same GPIO to trigger your lidar?

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@SivaRamaKrishnaNV Yes, how do I do that?

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Any update on this?

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Dear @sleff,
AFAIK, it is not possible. I am checking internally if there is way to get access to it.

9

Dear @sleff ,
It is not possible access GPIO which generates PWM signal connected to all deserializers.

11

Is there any other way to get a pulse signal at a frequency matched to the frame rate of camera capture?

1 Like
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I’m also interested in this topic, any update?