BBB Rev C Lockup - nothing logged


I have a very strange issue that I cannot seem to work out and get more info for!

We have a BBB Rev C that is powered via the 5V header pins. It also uses UART2 heavily (3MBps) and this is configured using the built in BB-UART2 device tree overlay.

The board is running… Debian Image 2015-10-04


What seems to happen is that the board drops off the network and also the serial debug cable I have attached becomes unresponsive. Nothing had been logged in the console at all on the serial cable and when it boots back up there is nothing in any of the previous syslogs at all to give even the hint of anything happening.

What is even more puzzling is that the network LED’s continue to flash!

To get this back I have to pull power and it then unsurprisingly works ok after that.

I’m trying to get to the bottom of this but if nothing is logged I don’t know where to go next!

Any ideas at all anyone?

Also further to that the USR LEDs are all extinguished but the LED’s on the NIC are ok and the power LED is still lit.

Anyone got any ideas, this is happening on a few units and nothing is logged at all.

Need to narrow down if it is software or hardware issue, from the Debian side of things it just looks like the power was removed from the unit however the NIC lights are still on and also the PWR light on the BBB. The BBB is powered via the SYS_5V pins.

I would not power the board using the SYS_5V pins. That is the output of the PMIC. Not sure what issues that would cause. It also sounds like that the boot pins maybe are being affected in some way that prevents the boot cycle after a power failure or removal.


Thank you Gerald,

Sorry I meant that we are using the VDD_5V pins to power the unit and not the SYS_5V. Fat fingers there!

With that in mind any sort of debugging we can do to tell if it is software our hardware?


What do you have on the board that is plugged in? Does it use any of the LCD pins?


Hi Gerald,

Not that I am aware of, We use UART2 & UART4 (TX & RX) and also GPIO3_19.

We also have the PWR_But & Sys_Reset pins wired in.

These units are booting fine and at some point in the future, can be anywhere from 15 mins of running to several hours they just exhibit the beahviour I describe. We are not sure where to look on the BBB side of things to see why it is in the state it is.

None of those should cause any booting issues



We are not seeing any booting issues though, the boards all boot fine and have never had an issue there. The boards are powered on and then simply look like they power off and trying to troubleshoot the issue, is there any info we can get by attaching to the PMIC at all?

I have a serial debug cable attached to the BBB and that simply logs nothing in the console and then becomes unresponsive. The OS is off, confirmed as it loses network and all TTY access. Pretty sure it is not software induced as nothing in logs etc when it does come back.

The only thing that gets it back and working is to remove and re-apply power.

What would cause this to happen is what we are trying to get to the bottom of.



How long does it take for this lockup?

Does the same board while not plugged into your design lock up after the
same amout of time?

Does every board you try lockup?

Are you using a genuine BBB or one from one of the clone makers?

Oh one more question

Does the board lockup while not running your application.


OK that is a start and I will look into those other points.

Is there any way to debug a hang like this where it simply locks up?

You might hook up a JTAG emulator and break in and see where it is stuck.


Ok thanks Gerald