Maximum output frequency of CAM0_MCLK

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

In “Sensor Software Driver Programming Guide”,
it says “The maximum frequency for extperiph1 is 24 MHz”.

Is this limitation (up to 24MHz) based on a software restriction? or hardware restriction?

If it is a hardware restriction, I would expect it to be described in a document like a datasheet, but unfortunately I couldn’t find it.
Could you tell me which document mentions this limitation for AGX Xavier?

I’d like to confirm a source of this limitation because I want to output 37.125MHz from CAM0_MCLK pin of AGX Xavier.

CaptureOf_SensorSoftwareDriverProgrammingGuide
CaptureOf_SensorSoftwareDriverProgrammingGuide1107×531 47.4 KB

Thank you for your support.

3

If the source is the extperiph1 it could configure to 37090909

4

Thank you very much for prompt reply.

Let me confirm your reply.
Do you mean that CAM0_MCLK pin of AGX Xavier can output up to 37.090909MHz?

Which document (like a datasheet) does mention it?
I need a solid evidence for this matter to design a circuit of sensor clock.

5

I check the clk tree from the debug fs.

/sys/kernel/debug/bpmp/clk/extperiph1/max_rate

6

Thank you very much for telling me the rationale.

However, you say up to 37.090909MHz and Sensor Software Driver Programming Guide says up to 24MHz.

Which one should I trust?

7

Could you help to check if can output 37Mhz by scope than I can check internal for the document.

8

Yes. I can check it by using a oscilloscope. However, unfortunately, I think I need a few working days to do it due to this COVID-19 situation.

Currently, my colleagues are doing remote work and I don’t have a AGX Xavier hardware. So, I need to arrange to get the hardware from my colleague.

I will start to arrange it and check MCLK output by using oscilloscope. Please wait for a while.

9

I just check it can be setted to 37090909 from the debug fs.
You can confirm it by the scope while you can do it.

10

Hi ShaneCCC-san,

I have checked the frequency of CAM0_MCLK by using a oscilloscope.
As the attached waveform, it is 37.09MHz. It means AGX Xavier can output 37.09MHz.

But, as I mentioned before, Sensor Software Driver Programming Guide says that the maximum frequency is 24MHz.

Could you please ask internally whether it is allowed by the AGX Xavier’s Hardware Specs to output 37.090909MHz on CAM0_MCLK pin?

tek00007
tek000071024×768 11.5 KB

Thank you in advance for your cooperation.

11

Thanks for your confirm. Will check if need to update the doc.

1 Like
12

Hi ShaneCCC-san,

Would you let me know the status of this issue?

I’m just designing schematics of camera clock for AGX Xavier. So, It would be greatly appreciated if I could reach a conclusion by the end of this week.

Thank you for your cooperation on this matter.

13

@m.watanuki
I think it should be OK if you have confirm the output from the scope.