I have a project where a BeagleBone Black will be completely inside a case. But I would really like to be sure that the board gets powered down properly when shutting down. Ideally I’d like to have a panel-mounted LED that mimicked the BBB power LED.
What is the best way to do this? My initial thought was to hook an LED up to the 5v supply… but that supply stays on even after a software shutdown.
FYI… I don’t really totally care whether the LED talks to the actual PMIC for this behavior. I just want a good way to make sure I don’t accidentally cause faults on my eMMC when shutting down the project.
How about a plastic light-pipe to carry the light from the board-mounted
LED to the front panel? It is a mechanical solution but pretty simple.
Mouser lists over 3500 options for doing this. Go to the Mouser web site
and search on "light pipe".
I wasn’t really considering a light pipe because the case is fairly large (8"x8"x4") and full of stuff to get around. It will need to be fairly visible in direct sunlight as well. I see that Mouser has a 6" flexible light pipe that might work… although I’m not sure how I’d keep it attached to the LED.
Although I acknowledge the simplicity of a mechanical solution I guess in this case I’d prefer an electronic one.
How about an LED with a series resistor from 3.3V to ground? Pin 9-3 or Pin 9-4.
If the BBB is powered up, there is 3.3V there. If the BBB has no power, there is not 3.3V there?
I really didn’t expect that to work since the 5v ports stay powered after a shutdown. However, I went ahead and tried it and you are absolutely right. The 3v ports go dark after a shutdown.
That is exactly what I need. Thanks!
I connected a led to pins 1 and 3, but the led stays on, won’t go off when I power the board off. Any other pin I can use?
On Sat, 3 Jun 2017 09:54:43 -0700 (PDT),
firstname.lastname@example.org declaimed the
I really didn't expect that to work since the 5v ports stay powered after
a shutdown. However, I went ahead and tried it and you are absolutely
right. The 3v ports go dark after a shutdown.
I connected a led to pins 1 and 3, but the led stays on, won't go off when
I power the board off. Any other pin I can use?
Does the third paragraph of page 46 in the SRM (rev C1) apply? (If the PMIC
is not shutdown, I'd expect voltages to be present)