Bricked AVR

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Bricked AVR

Kimson Muriungi
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.

Kithinji

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Re: Bricked AVR

Thomas D. Dean
On 03/25/18 12:05, 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.
>

https://learn.adafruit.com/usbtinyisp/avrdude

Tom Dean

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Re: Bricked AVR

Martin Stejskal
Hi,
 maybe dirty solution, but if you have some generator (or if you build one with 2x operational amplifier), you can push few hundreds khz to XTAL1 pin. Basically is is simple solution for SMD designs.
At least this worked with ATmega32 and 16.
Then you should be able to re-program fuses again.

Best regards
  Martin

On Sun, Mar 25, 2018, 22:18 Thomas D. Dean <[hidden email]> wrote:
On 03/25/18 12:05, 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.
>

https://learn.adafruit.com/usbtinyisp/avrdude

Tom Dean

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Re: Bricked AVR

Ormund Williams
In reply to this post by Kimson Muriungi
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


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