Timestamps on JetPack 4.6

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
1

Hello.

Our configuration is Jetson AGX Xavier DevKit with Camera Board LI-IMX390 by ConnectTech.

We flashed JetPack 4.6. After connected 2 LI-IMX390 cameras to J2 pins 1 and 2, only one LED lit up, which means that they are connected to one deserializer.

However, when we run 2 pipelines with nvarguscamerasrc, the frame timestamps are different.
And from launch to launch, sometimes the difference reaches only 1 ms, sometimes 16ms. Why is that?
We also corrected the nvarguscamerasrc code and get timestamp from iMetadata->getSensorTimestamp() instead of iFrame->getNumber(); but nothing changes.

In the same configuration but in version JetPack 4.4 the timestamps on the cameras are almost the same for example:

|leopard120_1|1669973828020551768|
|leopard120_2|1669973828020552504|
|leopard120_1|1669973828053885536|
|leopard120_2|1669973828053885056|
|leopard120_2|1669973828087217512|
|leopard120_1|1669973828087218632|
|leopard120_1|1669973828120553728|
|leopard120_2|1669973828120552640|

How can we synchronize 2 cameras in one serializer? We use this to build the camera disparity. And it is important for us that the timestamps are nearby.

Thanks.

3

Using getSensorSofTimestampTsc() to verify it.

https://docs.nvidia.com/jetson/l4t-multimedia/classArgus_1_1Ext_1_1ISensorTimestampTsc.html#ac6f2ccee516561329ee9aef39ad3d6d1

Thanks

4

ShaneCCC, thanks for your reply.

But we have different timestamp

iFrame->getTime() =                               2215763850000
iMetadata->getSensorTimestamp() =                 2215727908000
iSensorTimestampTsc->getSensorSofTimestampTsc() = 2220865493000
iSensorTimestampTsc->getSensorEofTimestampTsc() = 2220897841000

Why why does the timestamp (iMetadata) come earlier then Sof and Eof?
How to cast Sof and Eof to steady_clock and system_clock?

5

Have check below to transfer to system time.

6

Thank you.

But still use the method iSensorTimestampTsc->getSensorSofTimestampTsc() the timestamps are different for paired cameras.
The difference is from 0ms to 16ms. And when we restart the pipeline, it is always different.

7

Try boos the system to verify.

sudo nvpmodel -m 0
sudo jetson_clocks
sudo su
echo 1 > /sys/kernel/debug/bpmp/debug/clk/vi/mrq_rate_locked
echo 1 > /sys/kernel/debug/bpmp/debug/clk/isp/mrq_rate_locked
echo 1 > /sys/kernel/debug/bpmp/debug/clk/nvcsi/mrq_rate_locked
echo 1 > /sys/kernel/debug/bpmp/debug/clk/emc/mrq_rate_locked
cat /sys/kernel/debug/bpmp/debug/clk/vi/max_rate |tee /sys/kernel/debug/bpmp/debug/clk/vi/rate
cat /sys/kernel/debug/bpmp/debug/clk/isp/max_rate | tee  /sys/kernel/debug/bpmp/debug/clk/isp/rate
cat /sys/kernel/debug/bpmp/debug/clk/nvcsi/max_rate | tee /sys/kernel/debug/bpmp/debug/clk/nvcsi/rate
cat /sys/kernel/debug/bpmp/debug/clk/emc/max_rate | tee /sys/kernel/debug/bpmp/debug/clk/emc/rate
8

Run the commands, log below.
But the timestamps are different.

sda@jetson:~$ sudo nvpmodel -m 0
sda@jetson:~$ sudo jetson_clocks
sda@jetson:~$ sudo su
root@jetson:/home/sda# echo 1 > /sys/kernel/debug/bpmp/debug/clk/vi/mrq_rate_locked
root@jetson:/home/sda# echo 1 > /sys/kernel/debug/bpmp/debug/clk/isp/mrq_rate_locked
root@jetson:/home/sda# echo 1 > /sys/kernel/debug/bpmp/debug/clk/nvcsi/mrq_rate_locked
root@jetson:/home/sda# echo 1 > /sys/kernel/debug/bpmp/debug/clk/emc/mrq_rate_locked
root@jetson:/home/sda# cat /sys/kernel/debug/bpmp/debug/clk/vi/max_rate |tee /sys/kernel/debug/bpmp/debug/clk/vi/rate
998400000
root@jetson:/home/sda# cat /sys/kernel/debug/bpmp/debug/clk/isp/max_rate | tee  /sys/kernel/debug/bpmp/debug/clk/isp/rate
1190400000
root@jetson:/home/sda# cat /sys/kernel/debug/bpmp/debug/clk/nvcsi/max_rate | tee /sys/kernel/debug/bpmp/debug/clk/nvcsi/rate
400000000
root@jetson:/home/sda# cat /sys/kernel/debug/bpmp/debug/clk/emc/max_rate | tee /sys/kernel/debug/bpmp/debug/clk/emc/rate
2133000000
9

Did you run the sync_sensor sample code?
Also does this sensor board have HW sync design?

10

But in the Jetpack 4.4 version, there are no such problems with the same equipment.