Linux/DS90UB964-Q1: DS90UB964/DS90UB913 system's fps problem

user5344592

Prodigy 100 points

Part Number: DS90UB964-Q1

Tool/software: Linux

Hello,

Hardware system : soc + ds90ub964 + camera(ds90ub913 + sensor)

Image resolution : 1280*720

Problem : camera's fps is 30 fps, but the image received by SOC is only 15 fps.

Whether this is related to the transmission of FPD-LINK？Or do you have any other suggestions?

964's datasheet refers to the following,does this have some influence?

FPD3_PCLK is equivalent to PCLK frequency based on the operating MODE:
10-bit mode: PCLK_Freq. /2
12-bit HF mode: PCLK_Freq. x 2/3
12-bit LF mode: PCLK_Freq.

Thanks!

over 7 years ago

0 Jonathan Nguyen over 7 years ago

TI__Expert 4555 points

Hi,

What is the frequency of your PCLK? This frequency along with the blanking overhead of the display has a direct correlation to the frame rate of the display:

PCLK = (Horizontal Lines + Overhead) x (Vertical Lines +Overhead) x fps

Regards,

Jonny

Training on FPD-Link Serializer Deserializer devices and system: https://training.ti.com/fpd-link-learning-center

More information on IVI or ADAS FPD-Link products: http://www.ti.com/interface/fpd-link-serdes/overview.html

0 user5344592 over 7 years ago in reply to Jonathan Nguyen

Prodigy 100 points

Our debugging results:

when set 0x6d's bit3 to 0, the fps become 30fps.

but, we don't know why?

can you explain this?Thank you.

0 Jonathan Nguyen over 7 years ago in reply to user5344592

TI__Expert 4555 points

Hi,

The reason for this might be because you are not meeting the minimum timing requirements between frame valid and line valid. By default, if the minimum timing requirements are not met, the first video line will be discarded - resulting in missing frames which is why you would be seeing the 15fps.

While it seems that setting Register 0x6D's Bit3 to 0 seems to fix your problem, I would highly recommend adjusting the timing via register 0xBC. More info on the timing requirements for LineValid and Frame Valid is detailed in section 8.4.8 of the datasheet: www.ti.com/.../ds90ub964-q1.pdf

Training on FPD-Link Serializer Deserializer devices and system: https://training.ti.com/fpd-link-learning-center

More information on IVI or ADAS FPD-Link products: http://www.ti.com/interface/fpd-link-serdes/overview.html

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Linux/DS90UB964-Q1: DS90UB964/DS90UB913 system's fps problem