usbasp stopped working

[Hugo Balls]

Hi nerds.
About a month ago i built  my own little avr usb programmer http://www.fischl.de/usbasp/.
Today while I was debugging a simple project with Atmega8, 16x2 LCD and some I2C chips and out of nowhere
the software i was using to interface usbasp(Bascom avr) tells me that, it can't find it(the programmer itself). Avrdude - same.
So I checked everything, reinstalled drivers and nothing. I can get it working for about 5 seconds which can be achieved
by unplugging and plugging it back in(sometimes multiple times) then it stops working again, green led is always on, so its not all lost.
Thoughts? I'm thinking its a problem on the pc side(usb is fine though).
Specs:
Windows 10
ATmega8-16PU inside usbasp

[michaeliv]

Do you have another usbasp to test to see if that is working ?
I would guess that the built USBAsp stops functioning, try to see if the clock is still oscillating.
Also, after the 5 seconds, when it doesn't work any more, try re-flashing the firmware and see if that works.

[sleemanj]

Check the pull-up resistor on the RESET pin of the ATmega... if you don't have a pull-up on RESET add a pull-up on RESET.

If it's the OS shutting down the connection you should have a log entry with more details (on Linux you'd look in /var/log/syslog ; in Windows,  I dunno, I guess it's Event Viewer or something; in Mac, I dunno maybe it has /var/log/syslog as well).

Otherwise check voltage on the USB port to see if it's dropping too low (seems unlikely to drop so low that an AVR will shut down), and maybe more importantly, check for shorts on your USBAsp, if you have a "Charger Doctor" type device slap it in series and that will tell you if it is drawing abnormally high current or the voltage is abnormally low.

[Hugo Balls]

Pull-up on reset is there, voltages are fine, no shorts, green led is on. The thing is that windows seems to properly detect it but software can't.
Unfortunately I don't have  another programmer to reflash this one right now and no oscilloscope.

Here is some kind of log