Problem: Tiny45 USB device not recognized when PC is restart

[rinku]

Hi,
I was trying the Easy Logger project to understand the internal RC oscillator calibration of ATtiny45.

The device worked well until I restarted my PC (running on windows xp) with the device connected, then I get the message "USB device not recognized", i.e. the device fails to enumerate.
I have tried it to another PC also running on windows xp and the problem is also there.

The device works fine when I disconnect and connect physically to the PC, but the problem occurs when the device is connected to the PC and I shutdown the PC then Turn on again or restart the PC.

I know that the possible close calibration value is written in EEPROM and reloaded to OSCCAL during device reset, So why the problem is there?

Can any one check that it is a real problem(not my mistake) with the internal oscillator calibration for 16.5 MHz for ATtiny45?
How the problem can be solved?

Thanks..

[maxi]

My project also uses the tiny45 and is pretty much a hybrid EasyLogger design. I was curious when I read this post so I just tried re-booting with the device still attached.
The device did enumerate correctly but rather stangely my notebook took much longer to start-up than usual. (possibly pure coincidence)

All I have changed from the original EL design are the D+/- pins (I needed the T0 input) and made it into a custom class. Also I do not write the OSCCAL value to EEPROM if that could make any difference. I wonder though (just a wild guess) if enabling 'brown out detection' might help in your case, perhaps you already have it enabled?

[rinku]

Thanks for reply..

I did not make any change to the EasyLogger project, though I tried to solve the problem with the latest V-USB, but it doesn't help.

The device did enumerate correctly but rather stangely my notebook took much longer to start-up than usual. (possibly pure coincidence)

I don't think it is a coincidence, because my PC also takes longer time to start-up when the device is connected.

I wonder though (just a wild guess) if enabling 'brown out detection' might help in your case, perhaps you already have it enabled?

Yes, I already have done that, possible EEPROM corruption is the first thing came into my mind.