I'll chime in again too - we originally tested our 3v3-rx jumper with a direct connection, but then decided it might be nice to keep the ability to use the serial debug port. Right now we've got a 470 ohm resistor pulling rx up, which seems to allow communication over serial still. We also tried values of 220 through 1kohm and were still able to send characters to uart0. 100 ohm was too low to send anything over serial. I've not done extensive reboot testing yet with each of these, but we will likely settle on either 470 or 1kohm.
If you probe the RX pin of the BB with nothing attached, we find 0v. The TX pin (both on the BB and on the FTDI board we attach to the BB) is at 3.3v by default, and we've also noticed that the problem never occurs when we're hooked up to uart0 with our FTDI chip adapter. That made pulling the line up rather than down an attractive option. We did try pulling RX down to ground at some point, but the very first test I did after that resulted in power LED on but no boot. We still haven't done a mass deployment, so for now I'm taking our smaller testing runs and experiences like Ivan's to guide us. Sidenote - yes, we have noticed eth0 not showing up as well, although it's not critical for our application. On Thursday, August 13, 2015 at 4:04:34 PM UTC-7, Colin Bester wrote: > > In my case I am running 3.8.13-bone68 and system is pretty darn solid if > it does start up. I have not seen Ethernet fail nor have I had any random > reboots, but occasional I do have a device not power up when power is > applied. We have not been able to determine a consistent cause and I am not > convinced it's due to the mentioned RX pin as I am pretty sure I saw that > this pin is pulled low (which I still think is wrong polarity) on rev C > boards. > > In addition, we have physically blocked off the PWR button and only expose > the reset button via a small pin hole in our enclosure. > > > > On Thursday, August 13, 2015 at 5:42:23 PM UTC-5, [email protected] > wrote: >> >> Hi Robert, >> >> > Please confirm which kernel your running >> >> 3.8.13-bone71 (updated beginning of last June) >> >> > There's a big thread on this list, where a bunch spend about 2 weeks >> bisecting the v4.1.x kernel to find the cause of the "random" reboot.. >> >> I don't have an issue though with random reboots - the reboots are >> initiated on purpose by my application (because of the eth0 problem) - but >> as described 2 in 30,000 reboots failed. >> >> Cheers, >> Ivan >> >> -- 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.
