Hi, I have found the reason at last. The SYS_BOOT[0] become as 1, bbb SYS_BOOT[4..0] should be 11100 or 11000. But now it becomes 11101 or 11001 , so the onboard emmc boot fails.
在 2017年6月6日星期二 UTC+8上午11:13:08，[email protected]写道： > > I have two beaglebone black, all two board works well in the past. > Today one board fails(my lcd screen turn black), so I power off it and try > a restart, but after that it never bring up again. > > I attached TTL line to J1 to see what happened > 1, With no sd card insert, S2 button not pressed, power on, there is no > message out on my putty console, just nothing. > 2, I insert sd card and pressed S2 button, power on, I can see boot > messages and the board boot up success. > > I wonder whether emmc is crash or something else, so I use dd to clone the > first 2M data from emmc > dd if=/dev/mmcblk1 of=bad-2m.img count=16 bs=128k > > It success to clone data into file. > > From the good beaglebone black board, I get the same emmc img file, > good-2m.img > > I compare these two file and they are same, that means the MLO and > u-boot.img is well in emmc. > So I doubt the problem may be hardware problem, maybe: > 1, The power on initialize of emmc goes wrong, so the am335x rom code get > wrong MLO binary > 2, The am335x boot sequence wrongs, it does not boot from emmc by default. > > Do someone else faced same situation? > Or what can I do to debug what happened? > > > -- 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/0804221e-9118-4554-a0d9-8b3e18a1c899%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
