Be _extremely_ careful when plugging in the USB charging cable


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Hi,

here's what happened today:
I was working in the dark, and wanted to plug the USB cable in the micro Type B port.
But I mistakenly plugged it in the blue USB Type A port. I saw a little spark and realised my mistake.
I immediately tested USB devices, mouse and rj-45 adapter on both USB Type A ports: they were not working under PyraOS or Slackware anymore :'(:'(

I removed the battery for like 30 seconds, put it back. Didn't work :'(:'(:'(:'(
I removed the battery again 15 minutes, now I got back the ports, but only with PyraOS, only when the device boots without plugged-in devices, and most of the time it doesn't even work...

--EDIT:
Attached dmesg log.
 

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Sad to hear this after your great success with Slackware earlier.
Hmm, if some chips (partly) got killed through the spark, it's strange that the ports sometimes work in Pyra OS but never in Slackware...
This remembers me when I wanted to plug in USB devices on my Laptop in the dark, I sometimes was wondering why they don't work. I turned on the light and realized I put them in the RJ45 port... They fit perfectly in there :D
But at least there is no danger of a short circuit when you put a USB stick in the network port ;)
So yes, plugging in power cables in the dark can be dangerous...
 
Yes, I was sooo happy...
Could be randomness, or maybe a link between SD usage and USB.

Same happens to me with USB in rj-45 from time to time.

I tried a micro USB Type B to A adapter of mine on the working unit (have two Pyras), but this adapter didn't work with a mouse. Or is it the micro USB Type B port which is not configured to be used as host ?
The adapter looks like this one:
 

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Hi,

here's what happened today:
I was working in the dark, and wanted to plug the USB cable in the micro Type B port.
But I mistakenly plugged it in the blue USB Type A port. I saw a little spark and realised my mistake.
I immediately tested USB devices, mouse and rj-45 adapter on both USB Type A ports: they were not working under PyraOS or Slackware anymore :'(:'(

I removed the battery for like 30 seconds, put it back. Didn't work :'(:'(:'(:'(
I removed the battery again 15 minutes, now I got back the ports, but only with PyraOS, only when the device boots without plugged-in devices, and most of the time it doesn't even work...

--EDIT:
Attached dmesg log.
Oops... I had to think a little how you can plug a microUSB plug into the Blue or Black Type A ports...
Since the micro-usb has all contacts hidden inside, the theory must be that the metal shield of the microUSB plug did short circuit one of the USB A pins to their shield. Most likely you hit the +5V output of the USB port.
Indeed, this has a 100uF capacitor inside which has enough energy to produce a tiny little spark visible in the dark.
This 5V output comes from a voltage converter (TPS630701RNM converts battery voltage to +5V) and then goes through a TPS2561ADRC Dual Power Switch chip. This chip is current limited so it should sustain a short circuit on any of the USB A ports. This all alone doesn't explain that the USB ports appear to be broken now.
Unless the short circuit did damage something in the voltage converter or power switch chips despite protection. Just for information: these chips are sitting on the main board.
What else could be that in addition +5V was shorted to the USB data lines. These would go into the USB3503A hub chip on the processor board. I don't know which level of protection this chip has but it is a little unlikely that both ports are broken by such a connection on one port.
Now you say that PyraOS makes the ports sometimes work. This is difficult to find an explanation.
Indeed, the voltage converter and the power switches are controlled by GPIOs of the TCA6424 GPIO expander. So they may simply be controlled differently in your setup vs. PyraOS?
I have looked into the dmesg but some messages like "bad cable connected" are false indications by the kernel and the mentioned GPIOs have no trace in the kernel log.
What you could try is if you have any USB devices with a power-available LED (e.g. a device that can be charged from USB) it would indicate if the USB-A ports supply +5V or not.
 
I try to define the behavior with tests and trials, take this with a grain of salt:

I removed the battery the whole night.
So far, I have 5V on both ports even if when peripherals aren't working.
PyraOS or Slackware don't matter, it was randomness.
When it doesn't work, I have to let the unit off for around 15 min (could be less), then USB works again.
When it works, it works flawlessly.
Both ports seems to shows the same behavior.
It's been a few hours that it's working well, even after unplug/plug and shutdown or reboots.

On a side note, I noticed on both of my units that it seems that there's a bit of power in the USB ports after a shutdown because leds from USB devices briefly goes on when plugged in.
 
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