Re: [avr-chat] Bricked AVR

[Ormund Williams]

On Sun, 2018-03-25 at 22:05 +0300, Kimson Muriungi wrote:
> Hi guys,
> 
> I have a custom mega 2560 avr control board that I just got bricked
> by setting the wrong fuses accidentally. It is surface mount, so i
> cannot use fuse bit doctor or high voltage programming to reset it.
> Sadly I also didnt include JTAG in my design. The fuses have been set
> to Low frequency crystal oscillator. The only thing I have around
> that could help is a USBTiny ISP programmer, and a 32khz crystal,
> which i hoped would probably provide the low frequency to make it run
> as per the fuse settings. I have not managed to change that until
> now. I am aware that ISP programming frequency should be utmost 1/4
> of the 32 khz. Is there a way I can set ISP frequency of that level
> (6 to 8 khz) using avrdude and command prompt? Probably I'll be able
> to reset the fuses this way.
> 
> Or if there is any other way Id bring this chip back, I'd gladly use
> it.
> 
Avrdude has the -B switch you can set it to 125 to get an 8KHz ISP
clock that would work with a cpu clack of 32KHz. You'll then to inject
the 32KHz clock into the XTAL1 pin of the 2560.

__
Ormund