2032457_en-US

[#1]

i;MX8MP LVDS clock polarity

Hi all, 

We are using an #i.MX8MP  application processor to drive a LVDS panel on one of our custom board. The panel is currently not looking as expected. The text is barely readable, and we see some black (moving) flicker when we display a red screen. We have contacted the vendor of the panel, and they suggested to invert the polarity of the LVDS clock (from falling edge to rising edge or from rising edge to falling edge depending on the current setting). 

We then had a look at the reference manual of the #i.MX8MP. We did not find any relevant registers/information about the clock polarity of the LVDS interface. Do you have some information about the polarity of the clock? What is the default setting? Can this be configured? 

We have tried to swap the plus and minus clock signals as an alternative, but that does not work (voltage levels are different, so that is not unexpected). We also tried changing the polarity of the pixel clock in the LCDIF. However, then the panel looked exactly the same. Does someone have some other suggestions to troubleshoot or fix our problem?

Kind regards, 

Yoshi

Re: i;MX8MP LVDS clock polarity

Hi, 

Thank you for your reply. It was indeed an issues on our PCB. 

Kind regards, 

Yoshi

Re: i;MX8MP LVDS clock polarity

Hi @YoshiDev!

Is not possible to change the polarity in the iMX8MP.

What BSP version are you using?

What Display model are you using?

Have you configured well the device tree, clock rate, etc?

The most of cases behaviors like that are normal when the configuration is not the correct one.

I recommend to check your layout and verify the impedance of the LVDS signals too.

Best Regards!

Chavira