Lcd interface has strange data output for analog video encoder adv7393

Technical Support
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1

in a project a had to output analog video (pal/ntsc) and i decided to use the adv7393 from analog devices that is connected to lcd (rgb) interface of the apalis module. my implementation is mainly based on the approach:

i also implemented the kernel patches to support interlaced video output.

My kernelparameter in u-boot for vidargs is:
vidargs=video=mxcfb0:dev=lcd,LCD-576I50,if=RGB24 video=mxcfb1:off video=mxcfb2:off video=mxcfb3:off fbmem=32M

i also attached my device tree file for my implemantation
link text

so far everything looks good. i can start my system i have my framebuffer/video-devices, the setup on the i2c part of the encoder is correct and i can see some av video output. i have some timing issues on the av and not all of my monitors are happy with the video signal but this is another problem and might come from wrong mode settings.
but what confuses me is that not all of the 16 data bits that are fed into the adv7393 from the the lcd interface show data. i tested it with an oscilloscope and realized that i only have data output on even data bits (viewed from 24bit lcd interface side). all odd data bits stuck on gnd. this seems to be the case for all 24 data bits of the lcd interface. i tested only with the 16 data bits im using and a few more that i had access to, but im sure it is the same for all 24 bits.
hsync, vsync and pckl looks good.
Did i misconfigured something or did i forgot something?

2

What exact software versions of things are you talking about?

3

Hi @res,

Could you provide more information for us about your environment?
Like, which BSP version are you using?

Best regards,
André Curvello

4

Hello marcel.tx and adrecurvello.tx,

sorry for my late answer but the last two day i was out of office.

my BSP version is 3.0B4.

i adapted your console-trdx-image a bit to fit my needs.

so mainly my system is based on this.

i adapted kernel config of course to have support for adv7393 and others, patched the kernel as described in my first post to have interlaced support for ntsc and pal, modified device-tree (based on your ixora device tree), i also removed X11 stuff (want to try with directfb for my little graphic only output needs).

so far the system works prety fine and i see some video output on the av out that my monitor can display. i think i need some more adption with the timing but at least there is some output.

i see some boot information on start and a text console after start. but the graphics and text i see is erroneous somehow (wrong color), but interestingly not completely wrong.

With this i started investigating and after a while i put heavy measurment devices (oscilloscope) to the hardware and figured this strange behavior.

my first guess for the error was somthing releated to device tree an pin muxing for the lcd output pins (IPU1_DISP1 pins)

i adapted the pin muxing because i dont use all 24 pins for the lcd interface and a few of these pins are used for other purposes.

maybe my problem is somewhere here. but even without the changes for the lcd pin muxing the rusult is the same.

so im a bit confused and have no idea where to get my hands on next. i put a picture to show the effect on av screen. but with the missing data bits on the lcd interface the errorneous output ist “normal” somehow.

Btw: when i use the colour bar test function for the adv7393 encoder, the image that is shown up ist perfect (except alignment because of shity timing so far).

so i wouldnt expect circuit issues with the encoder itself (especially the analog part of the encoder).

i also have two identical prototypes of my hardware here for testing and both of them show the same result.

i’m pretty sure that i forgot somthing stupid or i misconfigured somthing but have no idea what kind of configuration or setting can lead to this strange behavior (even data bits show data and odd data bits dont).alt text

5

Hi @res,

Can you share with us your modified device-tree?

Best regards,
André Curvello

6

Hi André,

i thougt i did alredy in my first post. But i figured that i forgot to rename the link text.
But anyway i will upload it again.

our custom device tree

Best regards, René Schönrock

7

Hi @res,

Sorry, after reading again your original post, I saw that you’ve sent the device-tree.

I’m studying your case to identify what may be wrong here.

Best regards,
André Curvello