[AVR] Fusebit on atmega8 for 12MHz ?

[bianchi77]

Guys,

What's the fuse bit for atmega8 for 12MHz..?
Anyone has made a fusebit restorer with arduino ?

Thanks

 

[FenTrac]

The fuse settings for a 12 Mhz crystal are:
CKOPT = 1 - in hfuse
CKSEL3 = 1 - in lfuse
CKSEL2 = 1 - in lfuse
CKSEL1 = 1 - in lfuse
CKSEL0 = 1 - in lfuse

The fuses can be programmed using the -U option with avrdude , using an arduino as isp.

 

[bianchi77]

CKOPT = 1 - in hfuse I changed to 0, and now the chip is not responding, anyone knows how to fix it ? or it's broken already ? thanks

 

[FenTrac]

You will need to change the clock source to the one that the 4 clock fuse bits are programmed for.
Refer to ATmega8 datasheet Clock Sources, beginning at page 26, and Fuse bits, beginning at page 216.

To re-program the fuses using avrdude and an arduino, this tutorial might help.

https://learn.sparkfun.com/tutorials/installing-an-arduino-bootloader

 

[FvM]

If you managed to programm the atmega to a non-working clock configuration, you need to connect an external clock oscillator to reprogram it. Well described in the datasheet.