Tony Nixon wrote:

>Alessandro Marzini wrote:
>
>> I attached a .jpg scheme of my little project, can you help me?
>
>I looked at your jpg file. I would change the 220R resistors to
>something a little higher like 2K2. You are souring 22mA into each LED
>which are normally rated at 20mA.

I don't agree with this...  If you consider ohms law and the current
though a resistor is the voltage across it divided by it's resistance.  I
can see that you could think that 5v / 220 = just over 22ma but (as with
all diode devices) the LED drops some voltage across it self.  A normal
diode would drop 0.6 - 0.7 of a volt, but LED's usually drop about 1.7v
(this voltage drop is usually dependent on it's colour).    If you
re-calculate the current though the resistor you would be using a voltage
across it of 3.3v we get a value of 15ma.


With regard to the original problem, I would think that the watchdog
timer is enabled OR the fact that there is no decoupling capacitor (I
would think 0.1uf would be ok) across the psu pins.

Regards,

Brian.