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i.MX6Q TTL LCD u-boot and max resolution

Question asked by Josh Kurland on Dec 12, 2013
Latest reply on Mar 7, 2014 by rogeriopimentel
Branched to a new discussion



I am designing a video adapter that I intend to run from the output of the TTL LCD output port of an iMX6Q Wandboard.  But before I get started, I would like to ask a few questions.


1.)  What is the maximum resolution achievable over the TTL port?  According to the reference manual (IMX6DQRM.pdf page 2699) the parallel port supports SMPTE274 (1080i/p), which is the exact format that I need.  However most of my experience with this type of interface has been with very small LCDs.  Can anyone confirm that the 1080i/p standard is achievable? 

2.)   Currently I have just the TTL port enabled by adding to the console parameter:  'video=mxcfb0:dev=lcd,1920x1080@60,if=RGB24'.  I can measure data off the pins at the right times, but the pixel clock is not correct.  I believe this is due to my u-boot settings, specifically using RGB24.  If I intend to use the 20-bit YCrCb mode, what would be the appropriate setting?  Is there a table of all acceptable display settings in a reference manual that I can read?


3.)  Displaying over HDMI and TTL at the same time should be possible.  I assume the u-boot settings would look something like: 'video=mxcfb0:dev=lcd,1920x1080@60,if=see_question_2 video=mxcfb1:dev=hdmi,1920x1080M@60,if=RGB24.  Does it matter which frame buffer a display is on?  What would happen if I swap them so that HDMI is on fb0 and LCD is on fb1?

4.)  I am tinkering around with the idea of adding a small LVDS touch-enabled screen to my project as well.  This would be intended to display something else than what is on the HDMI and TTL LCD.  What will the u-boot settings look like then?  I have seen these three displays all operating this way before, but I am not sure how to replicate that setup. 

Thank you,

Josh Kurland