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

[Bernard Johnson]

Follow-up Comment #6, patch #7559 (project avrdude):

Actually, if you look at my patch and then look at ser_win32.c, my patch makes
the logic work the same on both platforms.  Windows has always been
bulletproof (and I can't tell you how much it bothers me that it wasn't on
Linux).  Once I made that change, it became just as reliable under Linux for
me (Uno).

Now that being said, what I haven't mentioned is that is not the problem I was
trying to fix.  I have a board with a FT232 and basically nothing is working
under Linux (works just fine in Windows).  My patch at least gets the board
reset after attempted programming, which was a step forward.  

With your patches, the close doesn't reset the device and start the code.  I
think unless you intend to remove serial_set_dtr_rts function, the logic has
to be reversed as I did otherwise places like serial_close will still be
reversed.

You're right though, the code is just confusing.  For example is_on is
unfortunately named because it implies current state rather than desired
state.

Btw, multiple times now you have said that your device resets on a DTR
transition to LOW: "Reset pulses can only occur at a HIGH-LOW transition". 
Unless I misunderstand you (and I do not have a logic analyzer), my Uno goes
into reset when DTR is pulled low, and then boots once DTR is released
(verifed by LED).  So long as I have DTR/reset pulled low, it does not boot. 
Is that what you see with your device?

So here is the end result with your patch:

Uno - works fine
Zigduino/FT232 - neither programs (this was also problem with my patch) or
boots when closing the device (appears that reset is held LOW)

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