On Wed, Nov 19, 2014 at 3:57 PM, Rick Reynolds <[email protected]> wrote: > Just an FYI... > > We are currently working on a project using Rev C BBB and RCN 3.13.11-bone12 > kernel. We had been experiencing random reboots. Sometimes multiple times > per day and sometimes once per day, mostly at night. We determined that the > reboots were only occuring when the BBB was being powered only from the 5VDC > connector. We never saw a reboot when the BBB was either powered from, or > just connected to, the USB OTG port. > > One of our engineers suggested that it might be a noise issue on the USB OTG > port and the way that the TPS65217C PMIC works in the system. The way he > explained it to me is that the PMIC is set up to default to the USB OTG port > for power. If you leave the USB OTG port open, or floating, while powered > from the 5VDC connector and then get noise on the USB OTG port then the PMIC > will attempt to switch to USB OTG port and finding that there is no voltage > there the system reboots. > > What we have done to solve the problem so far: I made a pigtail cable for > the USB OTG port that simply ties the shield, ground and 5VDC together. > There is no 5VDC on the USB OTG port when not connected to a host machine. > Not a great final solution but it did prove the theory. With the pigtail > installed we never get reboots, it's been tested on several BBBs now and is > very consistent. So, reboots regularly without the pigtail and never with > the pigtail installed. > > One other thing to note... On the schematic there are 4.7uF caps from both > the USB OTG and 5VDC lines to ground. We were thinking that this could allow > some relatively high frequency noise to pass to the PMIC. I don't know what > the response time, that would cause a switch over, is on the PMIC. It's > possible that something on the order of a .01uF - .1uF cap from the USB OTG > 5VDC line to ground might also solve the problem. This has not been tested > yet however.
Backport this line change (usb0:) https://github.com/RobertCNelson/linux-stable-rcn-ee/blob/3.18-rc5-bone1/arch/arm/boot/dts/am335x-bone-common.dtsi#L97 and nuke the "CONFIG_OTG" option.. Regards, -- Robert Nelson http://www.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 [email protected]. For more options, visit https://groups.google.com/d/optout.
