DS90UB954-Q1: How to disable LVDS signal

Hello Chris,

Which serializer/deserializer pair(s) does your set-up have? Please see this link below:

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/825722/serializer-solutions-rgb888-lvds-hdmi-to-fpdlink-iii-pair-with-ds90ub954 

The 954 DES converts a data stream from FPD-Link III to MIPI CSI-2. I am not sure where or how you are implementing LVDS in your system with the 954. Can you please explain?

Best Regards,

Shruti

Hi Shruti,

We pair 953 to 954, please check below picture, the 936/935 doesn't apply due to shortage, thanks a lot.

Hello Chris,

Are you trying to turn off the FPD-Link back channel? Please see register 0x58 and turn BC_ALWAYS_ON to off.

If there is no backchannel then the serializer would need to be in async mode. 

Best Regards,

Shruti

Hi Shruti,

We need to disable LVDS signal, it means all channel include forward, bi-directional, back channel, is it possible?

Thanks.

Hello Chris,

What is this "test to measure noise" that you mentioned earlier? What exactly are you trying to measure and test? Can you explain your set-up as well? 

Best Regards,

Shruti

Hi Shruti,

My board has LTE function and we are testing the over the air signal.

We found that when SERDES start to transmit image data the LTE signal gets bad.

And for the async mode of serializer you mentiond in previous post, do you mean Non-synchronous clocking mode? if the LVDS signal can't be disabled we're thinking about to slow its line rate, thanks. 

Hello Chris,

Chris Liu said:

And for the async mode of serializer you mentiond in previous post, do you mean Non-synchronous clocking mode?

Yes, I meant Non-synchronous clocking mode. 

To turn off the forward channel it would need to be done from the SER side - easiest method is to pull PDB = L on the 953. 

Best Regards,

Shruti

Hi Shruti,

Thanks for your reply.

If I set the 954 register 0x58 to 0x5d, which means Back Channel Frequency is 25Mbps, will the FPD-Link III data rate be around 2Gbps?