Pin protection on Arduino Due


It seems that the SAM3X is less "robust" than the ATmega2560, and more subject to "accident", as:

  • the operating voltage is 3.3V
  • max current per pin is.. I don't remember exactly, but about 10ma
  • in a general way no voltage outsite [-0.3 3.6V] should be applied

So I would like to use a "standard protection" on most of my pins, and I am interested in how you handle this.
Personally I have considered Zener diode 3.3V + Resistor 1kohm, on each pin.

But I realised that a standard (Zener) diode allows voltage as low as -0.8V, which is less than -0.3V....I suppose this is a problem?
So what do you suggest ?


On a related note, what would be the impact of including onboard series current limiting resistors on the DAC Outputs ?

There are a few of use that have blown these outputs through accidents of one type or another, however as the DAC output is almost always going to be going into some sort of an amplifier, I cannot see the inclusion of a current limiting resistor having any negative effect while providing protection against a range of common mistakes.

Duane B

Hi DuaneB,

Indeed on the DAC outputs I will apply the same kind of protection : Zener 3.3V + R1000.

When I read your sentence I understand that this resistor protection would have a “negative effect” on other pins… I don’t really see why ! (I mean, for most of the pins).


Are there other opinion ?
How do you protect your pins ?

How do you protect your pins ?

I don't connect them to anything silly. :wink:


How do you protect your pins ?

I don’t connect them to anything silly. :wink:

Yes like, thinking, planing, think again, (may correct it), wiring it, control it, powering it. But in hurry: wire it, power it (crossing fingers and hope the best), use it or get a new one…

True is the Due cost more than the other boards, the SAM3X is way more sensitive and it’s nearly impossible for some beginner to change the µC in an safe way. For the “NO RISK, NO FUN” section would be an UNO with DIP and an USBAsp the best option, on this combination there would not so much tears generate if something went horrible wrong. Change Burn and Ready.