After reading all about the WDT inside the sitara the only way to cold
reset the processor is to power cycle it OR
pull PMIC_PGOOD low which pulls PORZ low which will cold reset the IC.
IT seems to me that there is some shortsightedness of TI not allowing
the cold reset to be pulsed from a WDT.
In case of a processor hang where a warm reset cannot allow the IC to
recover.
So you may want to find that signal on the board and tie your external
WDT to it and see if this solves your problem.
Maybe in the next rev of the BBB this can be some how made available for
an external WDT.
On 12/2/2015 5:42 PM, William Hermans wrote:
> So just in case this is helpful to the whole process:
>
> william@beaglebone:~$ uname -a
> Linux beaglebone 4.1.9-bone-rt-r16 #1 Thu Oct 1 06:19:41 UTC 2015
> armv7l GNU/Linux
> william@beaglebone:~$ cat /etc/dogtag
> BeagleBoard.org Debian Image 2015-03-01
> william@beaglebone:~$ pstree
> init-+-bluetoothd
> |-cron
> |-dbus-daemon
> |-7*[getty]
> |-rpc.idmapd
> |-rpc.statd
> |-rpcbind
> |-rsyslogd---3*[{rsyslogd}]
> |-sshd---sshd---sshd---bash---pstree
> `-udevd---2*[udevd]
>
> The output of pstree is just to show that I'm not running systemd, but
> instead sysv.
>
> On Wed, Dec 2, 2015 at 5:38 PM, William Hermans <yyrk...@gmail.com
> <mailto:yyrk...@gmail.com>> wrote:
>
> /Element14 revC./
> /I think what you are describing is the power ramp issue. I
> don't think what I'm experiencing is the same thing. I've been
> through the power ramp issue and I just use my external KL16
> to toggle the BBB pwr button a few seconds after power is
> applied, which kicks the board into boot./
> /Jon/
>
>
> Not trying to be difficult, or argumentative . . . but no, I think
> we're experiencing the same thing. Only because the board will not
> boot up Linux at all after it gets into this state. The LEDs will
> cycle on, then off, but then nothing. I have to physically remove
> the power from the board for a few seconds, before it'll boot
> again. Passed that, sometimes, the processes of removing the power
> may have to be repeated a few times before the board does finally
> boot. However this last part seems to mostly apply to our A5A's
> mostly. I do not recall the Element14 RevC's doing this.
>
> On Wed, Dec 2, 2015 at 5:32 PM, Jonathan Ross
> <jonr...@nephology.org <mailto:jonr...@nephology.org>> wrote:
>
> Element14 revC.
> I think what you are describing is the power ramp issue. I
> don't think what I'm experiencing is the same thing. I've been
> through the power ramp issue and I just use my external KL16
> to toggle the BBB pwr button a few seconds after power is
> applied, which kicks the board into boot.
> Jon
>
> On Wednesday, December 2, 2015 at 4:27:49 PM UTC-8, William
> Hermans wrote:
>
> Which board revision Jonathon ? This board I noticed this
> on last night is an Element14 RevC. But on our A5A's I
> never noticed the USR LEDs cycling like that.
>
> On Wed, Dec 2, 2015 at 4:59 PM, Jonathan Ross
> <jon...@nephology.org> wrote:
>
> Got you on the script front. My issue is slightly
> different, when I get into my magic state, pressing
> the power button does nothing.
>
> On Wednesday, December 2, 2015 at 3:51:42 PM UTC-8,
> William Hermans wrote:
>
> /In my case linux is not booted at this
> time(none of the 4 user leds lit), so a script
> would not help. This is why I'm doing an
> external watchdog circuit.
> /
>
>
> Exactly. So here is what I mean. The USR LEDs
> cycle on for me *if* and only *if* I press the
> power button on the board. After that, nothing
> changes. Otherwise the LEDs are off, well the
> power LED is on, and the ethernet port lights are
> on too, and potentially blinking.
>
> The script, would just be to reboot the board in
> an attempt to put the board back into the bad
> state. For troubleshooting . . .
>
> On Wed, Dec 2, 2015 at 4:46 PM, Jonathan Ross
> <jon...@nephology.org> wrote:
>
> In my case linux is not booted at this
> time(none of the 4 user leds lit), so a script
> would not help. This is why I'm doing an
> external watchdog circuit.
>
> On Wednesday, December 2, 2015 at 3:41:32 PM
> UTC-8, William Hermans wrote:
>
> /I didn't test the 8 second holddown
> of the power button but I doubt it
> would help, and unfortunately it's not
> a reproducible issue. I'll have to
> wait for it to happen again./
>
>
> I know what you mean, e.g. this happens so
> erratically, it's hard to tell when it'll
> happen next. But, I could possibly whip up
> a script, and a means to automate
> resetting the system. Really, you could
> probably do the same as well. Just put
> "sudo reboot" in a bash script, and run it
> through rc.d
>
> With that said, I'm not 100% sure this is
> good for the board.
>
>
>
> On Wed, Dec 2, 2015 at 4:31 PM, Jonathan
> Ross <jon...@nephology.org> wrote:
>
> I didn't test the 8 second holddown of
> the power button but I doubt it would
> help, and unfortunately it's not a
> reproducible issue. I'll have to wait
> for it to happen again.
> From my notes, I was seeing zero volts
> on power, 5V on reset.
> The zero volts on power was very
> weird. From the KL16 I'm "toggling" my
> own effective power button that is a
> transistor between the power pin on
> the header and ground. The KL16 pin
> was not driven high (I checked), so I
> don't think it was the transistor on
> the cape that was pulling pwr to
> ground on the BBB. And the physical
> button wasn't pressed in. It was as if
> the pullup at the PMIC wasn't active,
> yet the power LED was on. Is that
> possible?
> Wish I hadn't pulled the 5V power to
> reset, then I could do more testing.
>
> On Wednesday, December 2, 2015 at
> 2:11:58 PM UTC-8, Gerald wrote:
>
> I would start with your cape
> design and try and rule that out
> first.
>
> The reset is an input pin read by
> the processor, not actually a HW
> power reset. If the SW is locked
> up, this could happen.
>
> If you hold the power button for a
> 8 seconds or more the board should
> power cycle.
>
> When it is in this state, what do
> the voltages read?
>
> Gerald
>
>
> On Wed, Dec 2, 2015 at 3:54 PM,
> Jonathan Ross
> <jon...@nephology.org> wrote:
>
> Once in a blue moon one of my
> beaglebones will get into a
> state where it has power (the
> power LED is lit), but it is
> not booted. Normally this
> would be fine, just hit the
> power button to reset. But in
> this weird state the power
> button does nothing. The reset
> button does nothing.
> I checked the power and reset
> button pins on the header, the
> power was low, the reset was high.
> The only way to get the board
> out of this state was to pull
> the 5V power.
> I'm using a KL16 on a cape to
> do a watchdog on the BB, and
> reboot it via power and/or
> reset buttons on the header if
> the BB stops sending checkins
> over uart. This has been
> working great, except for the
> rare case where the board ends
> up in this state where the
> power and reset buttons are
> not functioning.
> Any ideas how the BB could get
> into this state, and if
> there's any other way to force
> a reboot other than physically
> pulling the 5v power?
> Thanks,
> JR
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