TDA4VM: Problem about changing exposure time for IMX390 discovery on J721e

Xiaohan Zhou

Part Number: TDA4VM

Tool/software:

Hi TI experts

We have a problem about changing Exposure Time, we set AE mode on auto, and exposure_time_range to [100, 33333]

And AE algo is working, for we can see Analog Gain and Exposure Time changing, BTW Color Temperature is not 0, so we can say AWB is also woking?

But by judging from the images we took in different exposure time(100us and 33333us) and the same Analog Gain(1024). They seem the same!

So can not Exposure Time be changed so simply? Like being forced to set as 11000? Or it acutually is changing, just we need some more accurate tools to test?

Regards

Zhou

1 month ago

0 Gang Hua 1 month ago

TI__Guru 59390 points

Hi Zhou,

Xiaohan Zhou said:
So can not Exposure Time be changed so simply? Like being forced to set as 11000?

The exposure time should be fixed to ~11ms in the sensor driver provided by D3.
I don't see exposure time is changed by the sensor driver.
https://git.ti.com/cgit/processor-sdk/imaging/tree/sensor_drv/src/imx390_discovery/iss_sensor_imx390_discovery_common.c?h=main#n348

Hi Brandon Maciel , could you please confirm?

Using fixed exposure time is typical in ADAS use case because of LFM.

0 Brandon Maciel 1 month ago in reply to Gang Hua

TI__Prodigy 465 points

Hi Gang,

That is correct, the drivers SetAeParams function would need to have the logic to program the sensors AE registers. IMX390 Disco does not have that logic implemented.

0 Xiaohan Zhou 1 month ago in reply to Brandon Maciel

Prodigy 50 points

Hi Brandon

Thanks for answering

Is this mean that there's no way to change the exposure time of IMX390 Disco?

Regards
Zhou

0 Gang Hua 1 month ago in reply to Xiaohan Zhou

TI__Guru 59390 points

Xiaohan Zhou said:
Is this mean that there's no way to change the exposure time of IMX390 Disco?

Hi Zhou,

That is not supposed by our ADAS driver.
You would have to implement the driver function for changing exposure time.

0 Xiaohan Zhou 1 month ago in reply to Gang Hua

Prodigy 50 points

Hi Gang

Do you know how to write this function for IMX390 Disco? Or where could I find one?

Regards

Zhou

0 Gang Hua 1 month ago in reply to Xiaohan Zhou

TI__Guru 59390 points

Hi Zhou,

I am not familiar with sensor details myself.
You would need to refer to the IMX390 datasheet for how to program the sensor registers for exposure time.
Sony shall be able to help you better on this.

0 Xiaohan Zhou 1 month ago in reply to Gang Hua

Prodigy 50 points

Hi Gang

Ok, thanks for answering. I will ask for help from Sony.
I think I should close this problem

Regards

Zhou

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TDA4VM: Problem about changing exposure time for IMX390 discovery on J721e