Pro fails to enumerate

[defragster]

interesting - I've been hanging my Pro off a USB battery box sometimes for long runs (now I wonder if that relates to my issues ...) - is the update on each power up - or only when data xfers?  That could be a symptom changer as you describe it - but not a solution if the diode isn't running cleanly and the signal is compromised.

[gogol]

interesting - I've been hanging my Pro off a USB battery box sometimes for long runs (now I wonder if that relates to my issues ...) - is the update on each power up - or only when data xfers?  That could be a symptom changer as you describe it - but not a solution if the diode isn't running cleanly and the signal is compromised.

This is the comment, I was reading in github: https://github.com/micronucleus/micronucleus/commit/1e6cfd178fc302e5dd269444063745dd7b7a66c0

Jul 14th and 15th some more changes were pulled into, but unfortunately I miss discussion/comments why exactly this is happening, and which error is fixed with.

[gogol]

In the previous post I assumed, that the schematics looks like that, derived from the original digispark and the V-USB reference.

Code: [Select]

pin4-----------------------+--------------PB6 of attiny
                           |
                           |
                     solder-jumper
                           |
                         66R5
                           |
             GND ----zener-+---1k5---- +5V
                           |
                           |
                           |
                           
                         USB D-
respective

Code: [Select]

pin3-----------------------+--------------PB3 of attiny
                           |
                           |
                     solder-jumper
                           |
                         66R5
                           |
             GND ----zener-+
                           |
                           |
                           |
                           
                         USB D+

Now after looking through the schematics, I received from Erik, I see, that it looks like that:

Code: [Select]

pin4-----------------------+--------------PB6 of attiny
                           |
                           |
                     solder-jumper
                           |
                           |
             GND ----zener-+---1k5---- +5V
                           |
                         66R5
                           |
                           |
                           
                         USB D-
respective

Code: [Select]

pin3-----------------------+--------------PB3 of attiny
                           |
                           |
                     solder-jumper
                           |
                           |
             GND ----zener-+
                           |
                         66R5
                           |
                           |
                           
                         USB D+

Which means, the 66R5 series resistor comes after the Zener diode, which will pull the output of the attiny to 3.6V.  I have not enough electronic background to estimate, if that may be a problem for the attiny itself, when a high output is something like partially shorted to reduce the voltage to 3.6V (or even a little bit further).  That means, that the difference of 1.4V needs to be "burned" in the attiny.

When I use my original digispark as V-USB interface, the 66R5 resistor is between the pin and the zener diode, like in the original attiny. In that case, the 1.4V are burned from this resistor, resulting in approx 20mA, which is ok for the pin of the attiny. With a lower internal impedance, the current might go up to 100, 200mA.


Where are the electronic gurus??

[defragster]

I know enough to think I see why that is different going one direction - but these are bidirectional lines?  So the effect that clipped then dropped voltage one way is now dropping then clipping (less) that direction and the opposite change the other direction.  Will the voltage tend to need this conditioning one way more than the other as it isn't symmetric.

[saket]

Hi,
I am using digispark Attiny85 for last one week and it was working fine, but today suddenly it started showing following error while uploading
Please plug in the device ...
> Press CTRL+C to terminate the program.
> Device search timed out
 Please reply. i am on a deadline.
I have also read your solution on same issue with the pro, do I need to burn the bootloader? If yes then  how?