solid blue light - assistance welcome

Remork

hi there

last year i used a Bela in an art installation for a customer.
that installation was sold (fot quite the amount) and put in storage.
now it's on loan to a gallery, and it won't start up.. just a solid blue light on the bela.

i'm trying to remote-troubleshoot this, don't have the time to travel.
i was running a custom render file on the bela for display purposes, of which i cannot for the life of me find a copy.

if i have those people flash a new Bela image, i'm guessing i'll lose that render file..?
any way to access the bela and retreive it before we take drastic measures?

giuliomoro

Remork if i have those people flash a new Bela image, i'm guessing i'll lose that render file..?

yes

any way to access the bela and retreive it before we take drastic measures?

hmmm I'd try to boot from an SD card. If the bbb is not dead, but just the boot partition somehow corrupted and you manage to boot from SD card (see), you may be able to mount the emmc and access its data. If the BBB itself is dead, then ...

Many of the mmc1 (emmc) pins are broken out to the beaglebone's P8 header. I am not sure if this means that you can use them to access the emmc on an otherwise dead bbb, but forum.beagleboard.org may have answers to that.

You most likely need to get your hands on the BBB to be able to have a closer look, or it will be hard for you to guide someone to do this remotely.

Remork

i had them remove/reinsert the SD card.
without the SD card, it seems to start up to the Basic program, test tones work.
however, my own program seems to have vanished.
it loads the IDE, but

i'm gonna end up spending my sunday there, but i can't say i'm too thrilled about all this.. especially without a backup of the custom render file.. i'm hoping it lives on the SD card.

Remork

well, it appears to boot. to the Basic project.
that is, without my SD card inserted.

which is kinda good and bad at the same time?
it means it's not all dead, which is good.
however
i'm pretty sure i only used the Sd card for storage, though, not for my project files (Pd + custom render.)
the fact they couldn't access any other project in the IDE would therefore be bad..

giuliomoro

If it boots from the emmc and it shows only the basic project there, I would guess it did boot from your SD card previously. So the trick here is:
- boot from eMMC
- ssh into it
- insert SD card
- mount it with

mkdir -p /mnt/sdcard
mount /dev/mmcblk0p2 /mnt/sdcard

- check for errors in dmesg , e.g.: dmesg | tail -n 20
- check if projects folder on SD card is accessible:

ls /mnt/sdcard/root/Bela/projects

- copy the relevant (project(s)) to emmc:

cp -r /mnt/sdcard/root/Bela/projects/myproject /root/Bela/projects/

- now these are accessible from the IDE

Remork

giuliomoro - check for errors in dmesg , e.g.: dmesg | tail -n 20

not sure what that means. is that a command i need to run to check for errors, or is that a possible error i'm looking for?

Remork

will give that a whirl on sunday. thanks already!

giuliomoro

Remork
a command to run that may show some errors when mounting the SD card.

Remork

well, that was weird.

it wouldn't boot with the SD card inserted (probably trying to boot from sd card but failing?).
booted without it. inserted card and checked w/your mentioned method: no errors whatsoever.
still think the Belaboot partition was corrupted though, seems like the only logical (well, more or less) explanation.

so i copied the program files from the sd card to emmc, like you pointed out.
one is the display oled i2c OSC driver custom render yadiyadi which needs to run in the background, the other is the _main.pd.
both programs ran fine by themselves.
had to create a new service file for the background OSC part (forgot about that, took me far too long to figure that one out), and got a load of error messages saying that the service file i had just created (and checked!) didn't exist.
even while it was running fine in the background.. heh?

so tabula rasa: ended up backing everything up, reflashing the emmc, copied my programs to emmc and, again, created a new service file to run the oled I2C in the background.
used a new sd card (had to go through the procedure of automounting that one, obviously) for audiofile storage only.

it seems to work now, but i never want to go through that again 🙂

Remork

i also noticed that if i power cycled, sometimes Bela just wouldn't start. no lights whatsoever.
i'm running Bela off a built-in USB socket in a power strip, whose switch i'm using for mains power on/off.
it felt pretty random. sometimes it would boot, sometimes nothing at all. then i removed the USB cable, plugged it back in, and hey presto, booting again.
it did feel more prone to this behaviour when power cycling pretty fast - felt like the USB socket wasn't stable enough or couldn't provide the necessary current when starting up immediately after turning off. don't know.

luckily it's not a real life usage scenario (once it's booted, it stays on for the exhibition, and seems to run fine), but it doesn't feel sturdy enough for an artwork in a high-end museum collection.
thoughts?

giuliomoro

Remork it did feel more prone to this behaviour when power cycling pretty fast - felt like the USB socket wasn't stable enough or couldn't provide the necessary current when starting up immediately after turning off. don't know.

I am wondering whether this is because the power output of the USB socket doesn't go to 0V fast and monotonically. The BBB needs the voltage rail to go all the way to zero and stay there for a few ms before it goes back up. Also, there is a max time in the rise time from 0V to 5V (I am not sure about the exact timing requirements of either of these). It may be that your power strip does not put much thought / effort in having a clean power off / power up.

Remork

most likely power off that's the culprit then.
i can imagine, like most (cheaper?) usb chargers, it just kinda peters out instead of having a clean drop.
which would totally explain the behaviour upon quick re-up.

good to know it's not entirely unexpected - always worried it's the BBB or Bela that took a hit and starts behaving erratically. these kind of explanations do put my mind at ease 🙂