I can confirm that the pulsing detected by PMIC on USB_DC signal is the probing from USB-OTG.
After I disabled the USB-OTG in the kernel, the system has never rebooted. Btw I also re-loaded Angstrom image (3.8 kernel) and Andrew's Android image (with 3.8 kernel). I did not observe USB-OTG probing pulses on the VBus. I believe in the 3.8 kernel, the USB-OTG has not been implemented/enabled. That might be reason why it seems that 3.8 kernel doesn't have the random reboot behavior. On Wednesday, December 4, 2013 6:15:13 PM UTC-5, dek...@gmail.com wrote: > > > On Wednesday, December 4, 2013 1:45:02 PM UTC-5, lisarden wrote: >> >> The abstract from the TPS65217 datasheet to describe what is going on >> here: >> >> The linear charger periodically applies a 10-mA current source to the BAT >> pin to check for the presence of a >> >> battery. This will cause the BAT terminal to float up to > 3 V which may >> interfere with AC removal detection and >> >> the ability to switch from AC to USB input. For this reason, it is not >> recommended to use both AC and USB >> >> inputs when the battery is absent. >> > I wonder when the BAT terminal drifts > 3 V, if the PMIC behaves as > if V_BAT > V_UVLO. > > If so, I wonder what happens if AM335x USB-OTG probing drives VBUS > V_BAT > + 190 mV. That would exceed V_IN(DT). > > -- 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/groups/opt_out.
