After a pair of weeks of keeping the BBB off, I wanted to connect it again and I found it seems not to work anymore. Well, it does not work partially:
It does not boot if I power it up using the miniUSB (I have debian installed, with the uBoot loader corrected to allow 1 amp). The power led just flash for a moment and then it goes off. If I press the power button it is just the same: a short flash of the LED, then silence.
It does boot using the barrel connector, but in that case I can’t make the ethernet connection work.
From these symptoms I guess something have gone wrong with the USB host chip: It does not power the board, nor control the ethernet interface (it goes up in linux, but it just does not work; the lights in the RJ socket blink as expected though).
Is there anything to do before calling the board dead? It worked perfectly when I powered it down, so this (apparent) malfunction has been a nasty surprise…
J.
PS: I have flashed the NAND and the “native” Angstrom linux behaves just the same: it boots if I power the BBB using the barrel, but the network interface is completely deaf.
The USB is handled by the processor itself. Ethernet under USB power is always an iffy situation as the power derived form a USB host port on the PC is marginally enough for Ethernet.
Not sure what the issue here is. he short flash means the PMIC is shutting down due to an excess current detected on one of the power rails, including the USB input rail, If it exceeds 500mA the PMIC will shut off. Not sure about your override of the 500mA setting. That won’t make the PC generate more power.
Best bet based on what you have described would be an RMA and get it looked at.
Yup, I know, but I’m using a 1A USB power source. The same I used before, by the way… And the ethernet trouble is there when I power the BBB using a 2.4A power source via barrel connector.
I’m not sure it is worth the effort. I guess that would mean sending the card to the US… the parcel cost would probably be over the price of the BBB itself… so I think I will wait for the next batch of cards to get a new one.
FWIW I have had some wall-wort power supplies which were rated at 2 or 3 A, but had terrible transient response, thus causing dips in the 5V. I only found this by monitoring the 5V with a scope at the barrel connector.