USB device not recognized without resetting the board

SITCore
21

Then add a reset ic to make sure VCC is at full noise before liftoff.

22

Wouldn’t it make more sense to drop the second ldo and send the output of the first oki and USB into the second oki to make 3v3?.

23

I already have a software solution for that, no need for external circuitry :wink:

if (Power.GetResetSource() == ResetSource.PowerChanged) 
   Power.Reset();

That’s a dirty workaround, I know. But it works :wink:

Unfortunately, input voltage is 7V min :frowning:

1 Like
24

Righto, I will shut up now :roll_eyes:

25

No, please ! You don’t have only bad ideas :yum:

And I will try your idea by removing D5.

26

If it works you need to send me some cheese :grin:

27

you are right… You don’t have only bad ideas

28

I’ve always used ESD transient devices on the USB bus. Is it possible you have some kind of transient when you plug in? When you use external power, do you have the USB plugged in after external power is applied or plugged in and then apply power? With USB power you are plugging in at the same time, and the lack of USB could be a transient on the bus? What happens if you apply external power and then plug in the USB, does it then work?

I use this part.

https://www.mouser.co.id/ProductDetail/STMicroelectronics/USBLC6-2SC6?qs=po45yt2pPpu%2FhNIlwQdTlg%3D%3D

29

I also usually use this part on USB. But since the GHI dev board does not have one, I did not put it this time.
I will put it back for safety, it won’t hurt.

Scenario #1 :

  • I plug USB alone : no USB device on Windows but software on board running as expected
  • I then add external power : USB device recognized by Windows (while software still running)
  • I then remove external power : USB device still present in windows and usable (i.e. debugging app)

Scenario #2 :

  • I apply external power only : software on board running as expected
  • I plug USB : USB device recognized by Windows and usable
  • I then remove external power : USB device still present in windows and usable (i.e. debugging app)

The same one I brought once to you ? :wink:

30

Ah, the French cheese when it flows… It was rather nice :cheese:
Pity NZ border biosecurity laws would destroy any income cheese parcels :sleepy:

31

That’s crazy :astonished:

I’ve bought a powered USB hub this morning. Before using it, I wanted to test a last time without it to be sure of the “initial state”.
Guess what ? It does work today without external power !!! ???

The only difference between “before” and “now” is a Windows update in the mean time… :thinking:

That said, it takes more time for Windows to discover the board with only USB power. Even with powered hub. But it finds it.
Without external power, Windows takes roughly 5-6 seconds to detect the device while it lasts only 2-3 seconds with external power.
I did the tests on the same USB port of the PC.

So my design was not that bad, finally.

@Justin : No cheese today, my love is gone away… :stuck_out_tongue_winking_eye:

1 Like