Re: [avrdude-dev] Yet another config parameter

[Brian Dean]

On Fri, Feb 21, 2003 at 12:08:20AM +0100, Joerg Wunsch wrote:

> The strange thing though is, under Windows, it provides enough power
> to drive that m163, and there, using the port-supplied power is the
> only way to make that m163 enter programming mode at the first try,
> while with external power, it only enters programming mode after ~ 30
> attempts.

I wonder if this is a result from being able to better control the
state of /RESET and SCK when power is applied when the power is coming
from the parallel port, than externally.  The datasheet says that
/RESET and SCK must be held low at the time VCC is supplied with power
when preparing to enter programming mode.  It goes on to say that if
you can't guarantee this, you need to give /RESET a positive pulse
while holding SCK low.  Avrdude always does the latter, not knowing
for sure whether the parallel port is supplying power or not.

> driver.  I probably wouldn't want to ship an official (Unix) version
> that does direct port IO, for security concerns.

Agreed.  I wouldn't want avrdude to be the topic of the next security
advisory :-)

-Brian