Main > Raspberry Pi & Dev Board
Raspberry Pi2 320x240p via translating modeline to <hdmi_timings>
elvis:
HDMI does have a specific list of supported video modes:
https://en.wikipedia.org/wiki/Uncompressed_video#HDMI_Specifications
Back in the analogue days you could work around those limits as you pleased, but I'm not sure how that works at a hardware/firmware level with HDMI. Right there is the list of reasons why I don't like firmware as a solution to anything, and why I especially dislike hardware and software that prevents me doing as I please.
The Linux community is working on open source drivers for the GPU in the Raspberry Pi. I believe the latest 4.4 Kernel includes kernel modeset drivers to replace the proprietary blobs provided by Broadcom which are currently in use by most RPi distros. Hopefully that means in months to come, we as end users will have the control we want of the hardware we've purchased, rather than having the manufacturers artificially limit what we can do with the things we buy.
workspace:
Hello,
I managed to drive my Sony PVM with the VGA666 Adapter (via the UMSA - Ultimate SCART Adapter to get a csync instead vsync and hsync).
As wpt-nathan pointed out, the pixelclock has to be a divider of 19.2 for lower pixelclock speeds.
https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=112735
By try and error I found that this is the case for pixelclocks lower 31253817 Hz
This is my configuration/modeline/hdmi/dpi_timing that works:
dtoverlay=vga666
enable_dpi_lcd=1
display_default_lcd=1
dpi_group=2
dpi_mode=87
hdmi_timings=336 1 10 30 34 252 1 15 3 42 0 0 0 50 0 6400000 1 # 336:252 6.4MHz progressive
#hdmi_timings=500 1 14 45 56 375 1 240 5 5 0 0 0 50 1 9600000 1 # 500:375 9.6Mhz interlaced
As far as I see these are the only two resolutions at 15.625kHz the gpu can generate through the dpi interface (due the limitations on the pixelclockspeed. I would rather call it a bug)
But I might be wrong.
WalkToFreedom:
--- Quote from: workspace on November 19, 2015, 02:57:28 pm ---Hello,
I managed to drive my Sony PVM with the VGA666 Adapter (via the UMSA - Ultimate SCART Adapter to get a csync instead vsync and hsync).
As wpt-nathan pointed out, the pixelclock has to be a divider of 19.2 for lower pixelclock speeds.
https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=112735
By try and error I found that this is the case for pixelclocks lower 31253817 Hz
This is my configuration/modeline/hdmi/dpi_timing that works:
dtoverlay=vga666
enable_dpi_lcd=1
display_default_lcd=1
dpi_group=2
dpi_mode=87
hdmi_timings=336 1 10 30 34 252 1 15 3 42 0 0 0 50 0 6400000 1 # 336:252 6.4MHz progressive
#hdmi_timings=500 1 14 45 56 375 1 240 5 5 0 0 0 50 1 9600000 1 # 500:375 9.6Mhz interlaced
As far as I see these are the only two resolutions at 15.625kHz the gpu can generate through the dpi interface (due the limitations on the pixelclockspeed. I would rather call it a bug)
But I might be wrong.
--- End quote ---
Interesting! Will have to try a few things out, will post results. Thanks!
bleck:
--- Quote from: workspace on November 19, 2015, 02:57:28 pm ---Hello,
I managed to drive my Sony PVM with the VGA666 Adapter (via the UMSA - Ultimate SCART Adapter to get a csync instead vsync and hsync).
As wpt-nathan pointed out, the pixelclock has to be a divider of 19.2 for lower pixelclock speeds.
https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=112735
By try and error I found that this is the case for pixelclocks lower 31253817 Hz
This is my configuration/modeline/hdmi/dpi_timing that works:
dtoverlay=vga666
enable_dpi_lcd=1
display_default_lcd=1
dpi_group=2
dpi_mode=87
hdmi_timings=336 1 10 30 34 252 1 15 3 42 0 0 0 50 0 6400000 1 # 336:252 6.4MHz progressive
#hdmi_timings=500 1 14 45 56 375 1 240 5 5 0 0 0 50 1 9600000 1 # 500:375 9.6Mhz interlaced
As far as I see these are the only two resolutions at 15.625kHz the gpu can generate through the dpi interface (due the limitations on the pixelclockspeed. I would rather call it a bug)
But I might be wrong.
--- End quote ---
I tried this out on my Raspberry Pi 2 with an HDMI-> VGA adapter and I get a blank screen. So it looks like the VGA666 or something similar is needed to get those resolutions.
I've just been running at 720x240 using CEA mode 8 and setting RetroArch to integer scale and run at a 3:1 aspect ratio. That works for everything except for non-4:3 games and the extra black space is not visible thanks to my TV's overscan.
WalkToFreedom:
--- Quote from: bleck on November 23, 2015, 12:03:55 pm ---
--- Quote from: workspace on November 19, 2015, 02:57:28 pm ---Hello,
I managed to drive my Sony PVM with the VGA666 Adapter (via the UMSA - Ultimate SCART Adapter to get a csync instead vsync and hsync).
As wpt-nathan pointed out, the pixelclock has to be a divider of 19.2 for lower pixelclock speeds.
https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=112735
By try and error I found that this is the case for pixelclocks lower 31253817 Hz
This is my configuration/modeline/hdmi/dpi_timing that works:
dtoverlay=vga666
enable_dpi_lcd=1
display_default_lcd=1
dpi_group=2
dpi_mode=87
hdmi_timings=336 1 10 30 34 252 1 15 3 42 0 0 0 50 0 6400000 1 # 336:252 6.4MHz progressive
#hdmi_timings=500 1 14 45 56 375 1 240 5 5 0 0 0 50 1 9600000 1 # 500:375 9.6Mhz interlaced
As far as I see these are the only two resolutions at 15.625kHz the gpu can generate through the dpi interface (due the limitations on the pixelclockspeed. I would rather call it a bug)
But I might be wrong.
--- End quote ---
I tried this out on my Raspberry Pi 2 with an HDMI-> VGA adapter and I get a blank screen. So it looks like the VGA666 or something similar is needed to get those resolutions.
I've just been running at 720x240 using CEA mode 8 and setting RetroArch to integer scale and run at a 3:1 aspect ratio. That works for everything except for non-4:3 games and the extra black space is not visible thanks to my TV's overscan.
--- End quote ---
Arrrggghhhh, I haven't had a change to try it out yet, but I expect I'll get the same result. You can see in my first post I used the same settings but didn't know about the RetroArch config. Where would I set that? Also, what is your connection to the CRT? HDMI -> VGA to ?
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