you are messing with the boot pins. its been stated here 100s of times you cannot do anything to these pins before board boots. check the BBB schematic and the using the bbb board guide.,
On 4/23/2015 9:09 AM, Bit Pusher wrote: > I have found a reproducible boot freeze (on two boards); could someone > else possibly check; it's very easy to try. > No connections besides power plug and one (or two) wires from header > P8 to P9 > Scenario 1: connect P8-43 to P9-30, plug in power, only power light > comes on and BBB does not boot up > Scenario 2: connect P8-44 to P9-28, plug in power, only power light > comes on and BBB does not boot up > Scenario 3: connect both P8-43 to P9-30 and P8-44 to P9-28, plug in > power, power light and all 4 LEDs come on steady and BBB does not boot up. > > Discussion: > 1) doing these tests numerous times on 2 BBB's did not hurt either one > of the boards I have, but this behavior is so strange that it might be > risky; please don't be upset with me if it hurts your board. > 2) uname -a gives Linux beaglebone 3.8.13-bone70 #1 SMP Fri Jan 23 > 02:14:42 UTC 2015 armv7l GNU/Linux. My OS version is Debian wheezy 7.8 > 3) without wires connected, after booting and doing a > >sudo cat /sys/kernel/debug/pinctrl/44e10800.pinmux/pins shows > ... > pin 42 (44e108a8) 0000002f (this is P8-43 in mode 7 which should be > gpio2_8) > pin 43 (44e108ac) 0000002f (this is P8-44 in mode 7 which should be > gpio2_9) > ... > pin 102 (44e10998) 00000027 (this is P9-30 in mode 7 which should be > gpio3_17) > pin 103 (44e1099c) 00000027 (this is P9-28 in mode 7 which should be > gpio3_16) > > Therefore at boot, pins P8-43 and P8-44, without applying device > trees, are both configured as inputs with pull-downs; > pins P9-30 and P9-28, without applying device trees, are both > configured as inputs with pull_up/pull_down's disabled. > > 4) making the connections after boot does not have any discernible effects > > 5) It seems to me that having two gpio's connected together with both > configured as inputs and one having a pull-down should not cause the > BBB to freeze at boot. > 6) It is also interesting that having two connections as in 5) causes > different behavior; that is the boot process goes further to light all > four LED's and then freezes. > > Could someone check to see if they are getting similar behavior; I > can't imagine that I am doing something real stupid with only a single > wire connection; but I have previously done many rather stupid things > so you never know (without verification). > > Would someone in the expert category have some suggestions how to get > around this problem; if we can't find a work around, months and months > of work will be thrown away. For example, if we configured the device > tree that is loaded at boot up, would it take precedence before the > default pin mux that causes the freeze (if this happens to be the > problem, currently we have no insight into what is causing this behavior). > > Has anyone else seen similar problems (we may also have something > funny with connections to P8-45 and P8-46 but have not tracked this > down yet to simple scenarios. > > I'm open to suggestions as we are currently stuck. Thanks. > -- > 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] > <mailto:[email protected]>. > 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.
