I had flashed the 05.28 image to see if the USB hotplug issues I was experiencing had been fixed. Sadly, they had not… However, shortly after, I saw Koen’s repeated comments that 05.27 should be used and 05.28 should NOT be used. So I decided I better follow his advice since he built both images.
I noted that he has deleted the 05.28 flasher image to reinforce the point. Point taken.
I then prepared my 05.27 microSD card and in my SSH session issued ‘shutdown now’ for a graceful shutdown. BBB shuts down nicely. So far so good.
I unplugged the power cable, inserted the microSD card, held down the boot button, and plugged the DC power cable back in. Again, so far, so good.
Wait… no blue power LED.
This has never happened before, so I was puzzled. I tried again, same thing. Then it occurred to me that perhaps I should try the power button. I’ve never tried it before and I hadn’t seen how the updates in the 05.27 and 05.28 images would have affected the power button behavior before the linux kernel had loaded, so I didn’t expect it to work.
But it did. So now I’m more confused.
Unfortunately, I was forced to leave for work before the 05.27 flash concluded so I couldn’t try reflashing once the 05.27 image was flashed to the eMMC to verify that this behavior persisted with a 05.27 image on the eMMC.
Is this expected behavior after the recent patches to support the power button?
As a side note that is peripherally related (power and boot at least), I have noticed that if I have the DC power supply plugged in and I have connected the USB cable to a windows PC, I can’t actually gracefully shutdown using ‘shutdown now’ - the BBB reboots. If the USB cable is not plugged in, this works just fine. So without understanding exactly how the PMIC works (haven’t studied up on that yet) it seems that if VBUS is detected it will boot even if it has just been ‘powered down’ via software control (I2C perhaps? Not sure since I haven’t researched it yet). Is this also expected behavior or is it supposed to completely shut down when both the USB and DC are plugged in just like it does when only DC power is plugged in?
Thanks for the hard work! It’s been a steep learning curve for this windows/*nix workstation guy to figure out the bleeding edge embedded stuff, but I’m enjoying it so far.