RE: [avrdude-dev] programming 128

[Daniel Williamson]

Could you put in a voltage controlled reset circuit that will hold the reset
line on until the voltage is high enough to turn on? I think there is a
datasheet on avrfreaks (or atmels site) which has some example circuits on.
Commonly a slow RC filter is used to slow the rise time on the reset so it
comes on after VCC has risen.
Hopefully this will end up on the group?  Recently my posts seem to be
dissappearing!

Dan.

-----Original Message-----
From: address@hidden
[mailto:address@hidden Behalf
Of Erick Castillo
Sent: 16 May 2003 19:05
To: address@hidden
Cc: address@hidden
Subject: Re: [avrdude-dev] programming 128


On Fri, 16 May 2003, Lou wrote:

> On 15 May 2003 at 15:56, Erick   Castillo wrote:
>
> > The device has indeed worked. In fact, it's running now. But in order to
> > get it running, what i have to do is use 3.7 V to start up and then
raise
> > the voltage up to 5V so the other chips on the board get powered.
Finally,
> > I reset and everything works fine. It's just the boot up process that is
> > acting strangely.
>
> I would check those *other* chips too -- say a defective reset
> circuitry, an anomaly in the power supply chain, etc.
> Not to forget the clock circuitry: could be that power is rising
> too fast for the oscillator to stabilize, giving weird side
> effects.
>
> Lou

I scanned the board some and found that my reset circuit was
indeed somewhat defective. The reset pin was not rising with Vcc... once i
changed that, things got a little better. Now the issue I think is that
the power supply i have does not rise fast enough. If i keep the board
plugged in and shut the power supply and turn it back on, the board does
not boot. If instead I tap the power pin with the supply lead, then the
board boots fine. Strange behavior to say the least, but at least I know
my chips aren't defected... or at least that is the conclusion i've drawn.

Anyway, thanks for all the help folks.

--Erick



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