Reading through the revision 5.6 reference manual section 8.1.1 (LCD pins), it seems that configuring those pins out of order could create real electrical problem.
this is the relevant text: If you are using these pins for other functions, there are a few things to keep in mind: On the HDMI Framer, these signals are all inputs so the framer will not be driving these pins. The HDMI framer will add a load onto these pins. There are small filter caps on these signals which could also change the operation of these pins if used for other functions. When used for other functions, the HDMI framer cannot be used. There is no way to power off the framer as this would result in the framer being powered through these input pins which would not a be a good idea. These pins are also the SYSBOOT pins. DO NOT drive them before the SYS_RESETN signal goes high. If you do, the board may not boot because you would be changing the boot order of the processor. In order to use these pins, the SW will need to reconfigure them to whatever function you need the pins to do. To keep power low, the HDMI framer should be put in a low power mode via the SW using the I2C0 interface. On Friday, May 8, 2015 at 7:41:59 AM UTC+3, Yoram Rotbach wrote: > > Power led flashes for a sub second then turns off. As far as I understand > this means that the power controller has issues with initiating the boot > process. > No serial debug is active. I assume this is active once the CPU is awake. > > > On Friday, May 8, 2015 at 12:16:37 AM UTC+3, RobertCNelson wrote: >> >> On Thu, May 7, 2015 at 4:13 PM, Yoram Rotbach <yoram....@gmail.com> >> wrote: >> > Hi, >> > >> > I wanted to play with the latest Debian image on my A5C board. >> > After booting using HDMI display, everything was OK. >> > Then I've connected my 4D systems 70LCD , but nothing was shown. >> > So I've searched the web and found that adding >> > dtb=am335x-boneblack-4dcape-70t.dtb to /boot/uEnv.txt is supposed to >> solve >> > the problem. >> > So I did and this was the last time I saw my BBB alive :( It displays >> all >> > the symptoms of a blown processor. >> > >> > So my question is, could changing the uEnv.txt file the way I did >> damaged >> > the board? Is it possible to shorten GPIO pins this way? >> > >> > I wouldn't want this to happen again to my next BBB >> >> With the lcd not connected, what shows up on your serial debug? >> >> Regards, >> >> -- >> Robert Nelson >> https://rcn-ee.com/ >> > -- 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 beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
