Re: [avrdude-dev] [patch #7559] 'arduino' programmer type DTR transition fix

[Moses McKnight]

Hi folks, I haven't read this thread thoroughly so this may not be 
relevant, but there is a bug in several versions of the linux kernel 
relating to DTR that may be causing some of your problems.

http://marc.info/?t=128119600400004&r=1&w=2
http://thread.gmane.org/gmane.linux.usb.general/35985

I think the only fix is to use kernel 2.6.32-24 or before, or 2.6.37 or 
later.

Moses

On 07/16/2011 06:12 PM, Bernard Johnson wrote:
> Follow-up Comment #11, patch #7559 (project avrdude):
>
> "I don't want to turn this into a "which patch is better" discussion"
>
> Nope, not that at all.  I'm just trying to share what I see and what if any
> success I'm having.
>
> Thanks for verifying with a logic analyzer.
>
> "Nevertheless nothing of this changes the fact that only a HIGH-->LOW
> transition can cause a reset pulse if there is a capacitor between DTR and the
> reset pin."
>
> Agreed
>
> "Toggling the line twice always creates at least one H->L transition."
>
> Agreed, and my only concern was really around unintended consequences.  I
> can't really think of any though.
>
> "Why does your arduino require an additional reset after the bootloader is
> done? So far every bootloader I've used automatically starts the application
> after the upload is done. No additional external reset required here."
>
> I do not know.  There are several things I can't adequately explain with this
> board yet.
>
> "Regarding holding DTR low. This only keeps the AVR in reset state if DTR is
> wired directly to the reset pin."
>
> Sorry, what I meant was "as if held LOW" - The reason I say so is I can't even
> reset it with the reset button at this point.  It's literally like someone
> tied RESET to ground.
>
>
>
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