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TFP401A: Maximum Frame Rate Limitation ~1000Hz

Stephen Bauer
Prodigy 60 points
Part Number: TFP401A
Other Parts Discussed in Thread: TFP401,

ALL,

I am using the Adafruit TFP401. I am trying to create a custom display which is 128x128 with 1000 frames per second. I am using Ubuntu and CentOS Linux and I can create a proper modeline

Modeline "128x128@1005" 53.22 128 160 360 392 128 121 142 135 using the xtiming.sourceforge.net/.../xtiming.pl website.

This modeline creates a DOT CLK frequency 53 MHz which has a frame rate at 1005 Hz.

I sucessfully used the modeline below on a CentOS system.

# 128x128 @ 1000.00 Hz (GTF) hsync: 287.00 kHz; pclk: 50.51 MHz
Modeline "128x128_1000.00" 50.51 128 136 152 176 128 129 132 287 -HSync +Vsync  using the https://arachnoid.com/modelines/ 

This modeline I created a DOT CLK 50 MHz with a frame rate at 999.96 Hz.

Are there any limitation to the TFP401 unit? I see is the 999.96 Hz frame rate will load and the 1005 Hz frame rate will not.  My DOT CLK frequency is no where near the 165Mhz limit.

I am using a GTX1080 video card so I believe it is more than powerful enough to handle this.

  • 0
    TI__Mastermind 35130 points

    Hi Stephen,

    Are you still able to see the output clock and sync signals on an oscilloscope with this configuration?

    Regards,

    I.K.

  • 0 in reply to Ikechukwu Anyiam
    Prodigy 60 points

    Yes.  I have this hooked up to a 40-Pin breakout board.  It is by New Haven.

    NHD-FFC40

    https://www.newhavendisplay.com/nhdffc40-p-1155.html

    I have been using this to look at PIN 5 which is the first bit of the Red color to track the frame rate.

    I am doing a simple test of clearing the screen in white and then 4 clears in all black.  So I see the rate as 999.96 Hz.

    When I use the nvidia-settings utility, I see the rate is 999.96 Hz.   

    I am also using a function generator to generate a signal at 999.96 Hz to use as a reference signal.

  • 0 in reply to Stephen Bauer
    TI__Mastermind 35130 points

    Can you provide scope captures of ODCK, HSYNC, VSYNC, and DE for the 1005 Hz case?

  • 0 in reply to Ikechukwu Anyiam
    Prodigy 60 points

    Well, that is the dilemma I have.  When I try to run a modeline at 1005 Hz it fails to load.  I can load the other modeline at 999.96 Hz.

    So, that is why I was wondering if there is a limitation on the TFP401A.  

  • 0 in reply to Stephen Bauer
    TI__Mastermind 35130 points

    Hi Stephen,

    Sorry, not quite sure what you mean by loading a modeline as I'm only looking at this from the TFP401 perspective, and the TFP401 does not load anything in - it only takes DVI on the input and bridges it out to parallel RGB on the output.

    When it "fails to load" are you saying that the GTX1080 is failing to provide the TFP401 with a DVI input? 

    Regards,

    I.K.

  • 0 in reply to Ikechukwu Anyiam
    Prodigy 60 points

    I.K.,

    Sorry about the confusion.  I am using CentOS Linux.  What I am trying to do is use the Adafruit TFP401 to simulate a custom display.

    I am creating what is called a modeline which is used to set the screen resolution and pixel clock and frame rate for a display.  This is used by CentOS Linux.

    I was able to successfully load a mode line or setup the operating system to run at a frame rate of 999.96 Hz  I tried to run at 1005 Hz and for some reason it

    does not load or setup the operating system.  I have also tried other configurations of 300x300 500Hz, 1024x1024 200Hz,  So, I know that the operating system configurations I am trying work and are able to run on the TFP401.

    But as soon as I try a frame rate higher than a 1000 Hz I was having problems.  I was wondering if there was a limitation of the TFP401.

    This is an odd question and scenario so it has me a little stumped.

  • 0 in reply to Stephen Bauer
    TI__Mastermind 35130 points

    Hi Stephen,

    As you mentioned, that dot clock frequency is within datasheet specifications so I don't believe the TFP401 would have an issue with that frame rate and resolution. If I understand correctly it's your operating system that you're having issues with as it's not loading your modeline correctly so your graphics source is unable to provide the TFP401 with an input?

    Regards,

    I.K. 

  • 0 in reply to Ikechukwu Anyiam
    Prodigy 60 points

    I.k.

    You are correct.  I am also going to reach out to nVidia to see if there is a limitation there too.  I have one other idea.  I think I am going to try a modeline with 

    the modeline generator that works but try a frame rate above 1000 Hz.  I will let you know.

  • 0 in reply to Stephen Bauer
    Prodigy 60 points

    I.K,

    Thank you for your help.  I tried a frame rate above 1000 Hz.  It turned out to be 1001 Hz and it worked.  I am going to keep trying to

    see what the threshold is.  I will keep you posted here. 

  • 0 in reply to Stephen Bauer
    TI__Mastermind 35130 points

    Hi Stephen,

    Thanks for the update - glad you were able to get it working.

    Regards,

    I.K.