ISP freq. error with bootloader - AVR Studio 4

Hey all,
I’m attempting to burn the bootloader to the 168 chip using the Arduino board, and keep getting an error indicating that the speed at which I am trying to burn is too high - that the ISP frequency should be less than 1/4 of the target clock. Unfortunately, it is already set lower than this - I even tried setting it really really low and got the same problem.
I had no problem programming the fuses and the lock bit settings as per instructions, but it keeps having the same problem when I try to burn the bootloader onto the flash (or do the full Auto programming). I’ve tried a couple different chips, and am pretty much out of ideas. Any suggestions?

Thanks for the help,


Just to make sure, yoou are using the 168 fuse settings, right? The 8 and 168 have different, incompatible fuse settings. The 168 had 3 sets of fuse bits (total of 19 in use, IIRC) comapred to 2 sets on the 8.


Yep - set the fuse settings and the lock-bit settings were for the 168 - as shown in

One issue was that the instructions list one of the fuse settings as :

" Ext. Crystal Osc.; Frequency 8.0 - MHz; Startup time PWRDWN/RESET: 16K CK/14 CK + 64ms; [CKSEL=1111 SUT=0] ".

However, the closest wording corresponds to [CKSEL = 1111 SUT 11], which has wording "....; Start-up time PWRDWN/RESET: 16k CK/ 14 CK + 65ms;"

[CKSEL = 1111 SUT =0] corresponds to a wording "... ; Start-up time PWRDWN/RESET: "1k CK /14 CK + 65ms;"

I tried the process with both, but perhaps neither of my guesses was correct? The difference does not seem that crucial, but I'm not completely sure.

Thanks again, Brian

I didn't do the work of reading the datasheet - I just used -U hfuse:w:0xDF:m -U lfuse:w:0xFF:m -U efuse:w:0xF8:m on the avrdude command line and it worked. (I suspect 0x00 for the e fuse would be equivalent/better/less confusing, but that's another story.)