I am playing with an ATtiny13 and I thought it would be good to use it with an external 8Mhz ceramic oscillator instead of the 1.2 Mhz built-in one. (I want to do a soft-uart at 9600 bps, so I figured 1.2 Mhz was too slow)

To change to an external oscillator, I ran 'avrdude -c usbtiny -p attiny13 -U lfuse:w:0x70:m -U hfuse:w:0xff:m'

Unfortunately I can't access the device anymore now. The 'Blink the LED on PB0' program that was in there does not run anymore and the programmer can't connect to it.

Not sure what to do here. Can I throw away this chip or is there a way to rescue it?

  • 2
    \$\begingroup\$ What programmer are you using to write to the chip? \$\endgroup\$
    – Lou
    Commented Dec 4, 2009 at 22:21
  • \$\begingroup\$ According the the avrdude command line it was a usbtiny. \$\endgroup\$
    – JohnC
    Commented Dec 4, 2009 at 22:39
  • \$\begingroup\$ That doesn't necessarily mean it was a usbtiny, it could be a clone. \$\endgroup\$
    – Lou
    Commented Dec 7, 2009 at 13:42
  • 1
    \$\begingroup\$ Aren't Tiny13s like 80 cents? \$\endgroup\$
    – endolith
    Commented Dec 18, 2009 at 3:10
  • \$\begingroup\$ @endo more like $1.95 when not buying in bulk T_T \$\endgroup\$
    – Earlz
    Commented Apr 25, 2010 at 2:14

2 Answers 2


Have you tried to set the chip up with an external oscillator? Once the chip is programmed to use an external oscillator it will not work unless one is present. If you do not do this you will need hi voltage programming to reset the fuses.


You should absolutely be able to recover it. In the worst case, you might need a high voltage (12V?) programmer, though.

The fuse settings you used don't seem problematic to me. Brown-out detect is off (that can be a gotcha) and SPI is enabled, so you should be able to reprogram it just fine.

The main thing is that it looks like you set it to need an external oscillator. You were trying for that, so you probably have one around. You need it hooked up in the system you're using for ISP programming, but that should be the only issue.

IOW, you're not doing anything weird. It should all work. Double-check that you don't have any problems in your setup. Loose connections, that kind of thing.


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