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Author Topic: Supply for handmade arduino  (Read 1526 times)
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The diode prevents the  reset line from spiking up to a high voltage when the reset switch is used and causing the chip to think its going into high voltage programming mode, and appearing to the user as if it had locked up. This is implemented in later model Arduino's.
See Section 3 of Atmel App note.

* Atmel AVR042 AVR Hardware Design Considerations.pdf (236.19 KB - downloaded 8 times.)

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Measurement changes behavior
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AREF is also connected to AVCC, instead of being independent - with its own 0.1uF cap.
No diode across the reset resistor either.
Bare minimum designs have certainly been drawn up better:

That attached drawing has that old error on Avcc pin and C5.


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