Gerald, The pins are connected directly to the LVDS chip, a DS90C383BMT. Trace lengths are short and matched. But on the same board with the older software, it worked fine - what would have changed to require the use of a buffer?
Regards, James On Wednesday, July 30, 2014 3:43:38 PM UTC+1, Gerald wrote: > > Still could be the same issue. What buffer are you using to drive the > signals to the LVDS device? Are the trace lengths match to insure that all > the setup and hold times are met by having all signals with the same delay? > > Gerald > > > > On Wed, Jul 30, 2014 at 9:40 AM, James S <[email protected] <javascript:>> > wrote: > >> Hi Gerald, thanks for that reminder. >> >> However, there should be no such loading on the White since it doesn't >> have HDMI on board? The problem also occurs on the White. What else could >> it be? >> >> Regards, >> James >> >> >> On Wednesday, July 30, 2014 3:16:18 PM UTC+1, James S wrote: >> >>> We have a built a custom board with an LCD interface to drive a 1024 x >>> 768 pixel LVDS panel, 16BPP. It works great on the Beaglebone White with >>> the old Angstrom 3.2 using the board file configuration. >>> >>> We want to use the Beaglebone Black so we built up a system from >>> http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#2014-07-22 . I >>> added a dts using the same parameters from the old board file but the >>> graphics are blurred and corrupted. The card I made boots on the White also >>> and gives the same results as on the Black. See images below. >>> >>> I’ve fiddled with the panel timings but they don’t seem to have any >>> effect. >>> >>> Does anyone have any idea what is wrong and how do I fix it? >>> >>> Regards, >>> >>> James >>> >>> >>> >>> This is part of the (good) image from the frame buffer. >>> >>> >>> <https://lh6.googleusercontent.com/-4paVjDS0NME/U9j9QP7ZvyI/AAAAAAAAGjY/Tq2jYoa6r0Y/s1600/screen1.jpg> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> This is a photo of the output on the screen, showing a similar area. >>> >>> >>> <https://lh6.googleusercontent.com/-qR11mE7KhYU/U9j9wMohRZI/AAAAAAAAGjg/_lhBqXIQQyk/s1600/screen2.jpg> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> The following is the panel section of the dts file, based on an LCD4 >>> dts:- >>> >>> >>> >>> /* Settings for AUO G121XN01 / mita cape: */ >>> >>> panel { >>> >>> compatible = "tilcdc,panel"; >>> >>> pinctrl-names = "default"; >>> >>> pinctrl-0 = <&bone_mita_cape_lcd_pins>; >>> >>> panel-info { >>> >>> ac-bias = <255>; >>> >>> ac-bias-intrpt = <0>; >>> >>> dma-burst-sz = <16>; >>> >>> bpp = <16>; >>> >>> fdd = <0x80>; >>> >>> tft-alt-mode = <0>; >>> >>> stn-565-mode = <0>; >>> >>> mono-8bit-mode = <0>; >>> >>> sync-edge = <0>; >>> >>> sync-ctrl = <1>; >>> >>> raster-order = <0>; >>> >>> fifo-th = <0>; >>> >>> invert-pxl-clk = <0>; >>> >>> }; >>> >>> display-timings { >>> >>> native-mode = <&timing0>; >>> >>> timing0: 1024x768 { >>> >>> hactive = <1024>; >>> >>> vactive = <768>; >>> >>> hback-porch = <80>; >>> >>> hfront-porch = <48>; >>> >>> hsync-len = <32>; >>> >>> vback-porch = <15>; >>> >>> vfront-porch = <3>; >>> >>> vsync-len = <4>; >>> >>> clock-frequency = <56000000>; >>> >>> hsync-active = <0>; >>> >>> vsync-active = <0>; >>> >>> }; >>> >>> }; >>> >>> }; >>> >>> >>> >>> fb { >>> >>> compatible = "ti,am33xx-tilcdc"; >>> >>> reg = <0x4830e000 0x1000>; >>> >>> interrupt-parent = <&intc>; >>> >>> interrupts = <36>; >>> >>> ti,hwmods = "lcdc"; >>> >>> &nbs >>> ... >> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
