From: johan vermeire <[email protected]>
Reply-To: <[email protected]>
Date: Sunday, December 22, 2013 at 1:17 AM
To: <[email protected]>
Subject: Re: [beagleboard] beaglebone hdmi to VGA using powered Köning
convertor not working ?
> Hi john ty for the reply, but this i the uEnnv.txt that was on de sc-card and
> de beaglebone was running using this.
> I realy don't understand this. :(
>
> btw when i imput the sd-card now, power led and userled 0,1,2 are fixed light
> up .
> Damn still screwed :(
Hi Johan,
It isn¹t that complicated. Here is an explanation I provided back in Dec
4th.
=======================
BBB can boot from several sources, but I¹ll restrict this explanation to the
internal eMMC and the SDCard. uBoot considers the SDCard to be MMC 0 and the
eMMC is considered MMC 1. Both devices are configured the same; namely a
small FAT partition which stores MLO (first stage loader), u-boot (second
stage loader) and uImage (Linux Kernel); and a second partition formatted as
EXT4 which contains the linux filesystem. When you first boot, you will see
u-boot countdown (³Hit any key to stop autoboot²) which requires you to
press any key to enter the u-boot prompt. At the u-boot prompt, enter the
following command:
U-Boot# printenv
This line is probably the most important to understand how BBB boots:
bootcmd=gpio set 53; i2c mw 0x24 1 0x3e; run findfdt; mmc dev 0; if mmc
rescan ;
then echo micro SD card found;setenv mmcdev 0;else echo No micro SD card
found,
setting mmcdev to 1;setenv mmcdev 1;fi;setenv bootpart ${mmcdev}:2;mmc dev
${mm
cdev}; if mmc rescan; then gpio set 54; echo SD/MMC found on device
${mmcdev};if
run loadbootenv; then echo Loaded environment from ${bootenv};run
importbootenv
;fi;if test -n $uenvcmd; then echo Running uenvcmd ...;run uenvcmd;fi;gpio
set 5
5; if run loaduimage; then gpio set 56; run loadfdt;run mmcboot;fi;fi;
U-Boot# gpio set 53
sets LED0 (D2)
U-Boot# run findfdt
runs the following command:
findfdt=if test $board_name = A335BONE; then setenv fdtfile am335x-bone.dtb;
fi;
if test $board_name = A335BNLT; then setenv fdtfile am335x-boneblack.dtb;
fi; i
f test $board_name = A33515BB; then setenv fdtfile am335x-evm.dtb; fi; if
test $
board_name = A335X_SK; then setenv fdtfile am335x-evmsk.dtb; fi
which determines the board type, in this case fdtfile=am335x-boneblack.dtb
Next, mmc is set to dev 0 (mmc dev 0), which is the SDCard. (mmc rescan)
checks to see if the SDCard is installed and if it is, mmcdev=0 (setenv
mmcdev 0) and if not, mmcdev is set to 1 (setenv mmcdev 1). Next, bootpart
is set to 0 if the SDCard is installed; otherwise, it is set to 1.
I won¹t go into detail for the remainder, but you can now see that the
following commands are run:
U-Boot# run loadbootenv //loads uEnv.txt into memory
U-Boot# run importbootenv //imports uEnv.txt from memory into the u-boot env
U-Boot# run loaduimage // load uImage into memory
U-Boot# run loadfdt // load devicetree
U-Boot# run mmcboot // runs the linux kernel
BTW, you could always enter these commands individually and if you do this
correctly, you will boot the BBB successfully.
It is the linux kernel that mounts the second partition (ext4) which
contains the filesystem and then the init scripts are run to configure and
setup everything needed for device drivers, display a login console and
present a graphical environment available.
This is a very brief description, but I hope it is enough to help you
understand the remainder of the u-boot environment and see how it works.
========================
Best advice I can give you is enter these commands one at a time and check
the results.
I hope this helps,
Regards,
John
>
> gr; johan
>
> Op zondag 22 december 2013 02:22:52 UTC+1 schreef John Syne:
>>
>>
>> From: johan vermeire <[email protected] <javascript:> >
>> Reply-To: <[email protected] <javascript:> >
>> Date: Saturday, December 21, 2013 at 4:14 PM
>> To: <[email protected] <javascript:> >
>> Subject: Re: [beagleboard] beaglebone hdmi to VGA using powered Köning
>> convertor not working ?
>>
>>> Hi Gerard i realy f* it up now :(
>>> When i was testing my setup i finally found a tv that show me the screen at
>>> 1280x720(16:9)
>>> but when i connect the vga convertor i see 1/2 screen @ the same resolution.
>>> -> that's the problem why the other tv's won't show annything i think.
>>>
>>> I found that i need to edit the uENV.txt file to test other resolution
>>> settings (only working at startup i know)
>>>
>>> i putted the sdcard (beagle starts unbuntu) in my windows pc and added an
>>> extra line for the resolution, the beagle din't show me anny screen, after
>>> that even when i removed that extra line. the beagle still din't show
>>> annything :(
>>>
>>> I destoyed the file i gues :(
>>>
>>> i uploaded the file.
>>>
>>> When i can't fix this back i'm screwed my sister payed 500 eur for this
>>> beagle +install (yea i know this is nuts) but there was this hdmi problem
>>> and i'm a video guy so she asked to try to fix this but now this :(
>>>
>>> i hope you can help me out here. :(
>> Hi Johan,
>>
>> Your uEnv.txt file doesn¹t make any sense. All the actions you included are
>> already done in the default u-boot script. You should only add the actions
>> you need and not attempt to replace the default u-boot script. Also, you
>> should add these items to uenvcmd, not optargs. When you boot, stop at the
>> u-boot prompt and enter the printenv command. That is the default u-boot
>> script before uEnv.txt is loaded. You will see that after uEnv.txt is loaded,
>> it will check if uenvcmd exists, and if it does, it will be run uenvcmd.
>>
>> I have attached an example uEnv.txt I found that may demonstrate some of
>> these concepts.
>>
>> Regards,
>> John
>>> gr; johan
>>>
>>>
>>> Op donderdag 12 december 2013 20:46:25 UTC+1 schreef Gerald:
>>>> Not until the SW can let you do it. The DRM drive handles all of this and
>>>> it uses the EDID to pick the resolution.
>>>>
>>>> Gerald.
>>>>
>>>>
>>>> On Thu, Dec 12, 2013 at 12:13 PM, johan vermeire <[email protected]>
>>>> wrote:
>>>>> So there is no solution then :(
>>>>>
>>>>> gr; johan
>>>>>
>>>>> Op donderdag 12 december 2013 18:42:52 UTC+1 schreef Gerald:
>>>>>> That would indeed be nice.
>>>>>>
>>>>>> Gerald
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Thu, Dec 12, 2013 at 11:36 AM, johan vermeire <[email protected]>
>>>>>> wrote:
>>>>>>> Would it be possible to set a fixed resolution on the beagle.To
>>>>>>> solve this problem?
>>>>>>> How more i work with Hdmi how more i miss vga ...
>>>>>>> gr. johan
>>>>>>>
>>>>>>> Op donderdag 12 december 2013 17:02:24 UTC+1 schreef Gerald:
>>>>>>> It depends on what the EDID reports. The DRM driver uses that
>>>>>>> information to select the highest resolution. VGA has its limis, that is
>>>>>>> why HDMI was created. So it is possible that there could be limits to
>>>>>>> waht the VGA can support on certain TVs. TVs as such are not always
>>>>>>> friendly to PC type displays.
>>>>>>>
>>>>>>> Gerald
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Dec 12, 2013 at 9:21 AM, johan vermeire <[email protected]>
>>>>>>> wrote:
>>>>>>> Btw the tv's that are not working behind the vga convertor, are working
>>>>>>> when i use the HDMi connection.
>>>>>>>
>>>>>>> Op donderdag 12 december 2013 16:14:59 UTC+1 schreef johan vermeire:
>>>>>>> Hi Gerald it looks like te convertor does his job :).
>>>>>>> It just does not work on certain tv's.
>>>>>>> Is it possible dat de beaglebone communicate with the convertor and
>>>>>>> choose then the highest resolution --> but unsupported by the tv's ?
>>>>>>> I'm not really at home with EDID . :s
>>>>>>>
>>>>>>> gr. johan
>>>>>>>
>>>>>>> --
>>>>>>> For more options, visit http://beagleboard.org/discuss
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>>>
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