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Noise on the Display DT070BTFT

Hi,

We are observing some noise on the display (continous horizontal lines).

Is it possible that because of the power supply noise, we may see the noise on the Display?

If yes, which power may effect the display? 

What can be done for the same?

Help would be appriciated.

 

Thanks & Regards,

Nanjunda M

Replies

engineering_seacomp's picture
engineering_seacomp
December 6, 2018
Hi Nanjunda,
 
Is your question on the noise because our recommendation of removing the capacitors on the LVDS lines for the schematics you provided?
 
The display uses LVDS signal pairs.  Are you familiar with that type of signal?  These are DC differential signals and will not be affected by the noise created by the power supply.  You need to remove your capacitors on the LVDS signal lines (C374, C375, etc) with a jumper.
 

Did you use the following LVDS layout recommendations for IMX6 from the IMX6DQ6SDLHDG pdf?

•Follow standard high-speed differential routing rules for signal integrity.

•Each differential pair should be length matched to ± 5 mils.

•LVDS differential pairs should have a differential impedance of 100 ohm

•Note that there are no pad control registers for the LVDS signals. So drive strength is not controllable through software.

 

 
 

•The space between two adjacent differential pairs should be greater than or equal to twice the space between the two individual conductors.

•The skew between LVDS pairs should be within the minimum recommendation (± 100 mil).

 
 
Once you have all the hardware working using the above design rules from the reference Hardware Development Guide from IXP, you can then start to look at software.
 
 
For software, IXP / yocto will provide instructions on how to setup the kernel and bootloader for use with an LVDS display.  The only parameters that are needed for the display (after proper setup) where previously provided:
 

static const struct fb_videomode custom_mode = {

  /* 1024x600 @ 60 Hz, 31.5 kHz hsync */

NULL,

60,

1024,

600,

19512,

140,

160,

20,

12,

20,

3,

3,

FB_VMODE_NONINTERLACED | FB_VMODE_ASPECT_16_9, FB_MODE_IS_VESA,

};

We have a custom IXP solution we use for in-house development, which you cannot buy off the shelf. It is propratory as it is used in product development.  There is nothing special about our LVDS display, as it uses the LVDS standard that IXP also references.

 
It's hard enough to get an custom IXP design to work (both hardware and software), let alone trying to implement on an FPGA as in your project.
 
I hope this helps, as I won't be able to provide support for debugging of your custom hardware and software.
 

Thanks,