riph72-lumi
Posts: 34
Joined: Wed Jul 19, 2017 8:41 am

DPI video signals

Thu May 17, 2018 9:04 am

Hello all,

I'm trying to get a 320 * 240 LCD display working via the DPI interface, and have stumbled across a strange problem - if I use the following for testing the Pi3 video signal output:

#1920x1080 60Hz
dpi_group=2
dpi_mode=82

...I see signals on PCLK, HSYNC, VSYNC. But if I use this:

#640x480 60Hz
dpi_group=2
dpi_mode=4

...there are no signals. Both are standard DMT modes, so why the lack of signals in the latter config?

I also see no signals when I try to use dpi_output_format/hdmi_timings for a custom mode, but am hoping that understanding the issue with dpi_mode=4 will shed light on things...

Thanks,
Richard.

macload1
Posts: 14
Joined: Mon Jul 07, 2014 6:50 am

Re: DPI video signals

Tue Jun 25, 2019 8:11 pm

Dear riph72-lumi,
Did you finally find out where that comes from? I think I have a similar problem than you. I also want to make work a 320x240 LCD using DPI.

My custom settings for a 800x480 and for a 420x272 displays are working perfectly, but when I switch to the 320x240 settings (still custom ones) there is no more signals on HSYNC, VSYNC & PCLK.

Could you help me resolving that issue? Is it a limitation of the Videocore, not to output a signal that is too slow?

Best regards,
macload1

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